/* Cert Prep — offline study app. Tokens follow the dataviz reference palette; dark mode is its own set of steps. */

:root {
  color-scheme: light;
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --raised: #ffffff;
  --fill: #f0efec;
  --fill-2: #e6e5e0;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --ink-3: #6b6a65;
  --axis: #898781;
  --grid: #e1e0d9;
  --line: rgba(11, 11, 11, 0.10);
  --line-strong: rgba(11, 11, 11, 0.20);
  --accent: #2a78d6;
  --accent-ink: #1c5cab;
  --accent-wash: rgba(42, 120, 214, 0.08);
  --accent-wash-2: rgba(42, 120, 214, 0.16);
  --btn: #2a78d6;
  --btn-hover: #256abf;
  --good: #0ca30c;
  --good-ink: #006300;
  --good-wash: rgba(12, 163, 12, 0.09);
  --bad: #d03b3b;
  --bad-ink: #a82727;
  --bad-wash: rgba(208, 59, 59, 0.08);
  --warn: #fab219;
  --warn-ink: #7a4f00;
  --warn-wash: rgba(250, 178, 25, 0.18);
  --m-new: #e6e5e0;
  --m-learning: #86b6ef;
  --m-reviewing: #3987e5;
  --m-mastered: #1c5cab;
  --heat-0: #ebeae5;
  --heat-1: #86b6ef;
  --heat-2: #5598e7;
  --heat-3: #256abf;
  --heat-4: #104281;
  --other: #b9b8b0;
  --shadow: 0 1px 2px rgba(11, 11, 11, 0.05);
  --shadow-lg: 0 16px 40px rgba(11, 11, 11, 0.14), 0 2px 8px rgba(11, 11, 11, 0.06);
  --scrim: rgba(11, 11, 11, 0.45);
  --radius: 12px;
  --radius-sm: 8px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --topbar: 56px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --page: #0d0d0d;
    --surface: #1a1a19;
    --raised: #222220;
    --fill: #2c2c2a;
    --fill-2: #383835;
    --ink: #ffffff;
    --ink-2: #c3c2b7;
    --ink-3: #a3a29a;
    --axis: #898781;
    --grid: #2c2c2a;
    --line: rgba(255, 255, 255, 0.10);
    --line-strong: rgba(255, 255, 255, 0.20);
    --accent: #3987e5;
    --accent-ink: #86b6ef;
    --accent-wash: rgba(57, 135, 229, 0.14);
    --accent-wash-2: rgba(57, 135, 229, 0.26);
    --good-ink: #0ca30c;
    --good-wash: rgba(12, 163, 12, 0.14);
    --bad-ink: #e66767;
    --bad-wash: rgba(208, 59, 59, 0.16);
    --warn-ink: #fab219;
    --warn-wash: rgba(250, 178, 25, 0.14);
    --m-new: #2c2c2a;
    --m-learning: #184f95;
    --m-reviewing: #2a78d6;
    --m-mastered: #6da7ec;
    --heat-0: #2c2c2a;
    --heat-1: #184f95;
    --heat-2: #256abf;
    --heat-3: #3987e5;
    --heat-4: #86b6ef;
    --other: #5c5b56;
    --shadow: none;
    --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.6);
    --scrim: rgba(0, 0, 0, 0.6);
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #0d0d0d;
  --surface: #1a1a19;
  --raised: #222220;
  --fill: #2c2c2a;
  --fill-2: #383835;
  --ink: #ffffff;
  --ink-2: #c3c2b7;
  --ink-3: #a3a29a;
  --axis: #898781;
  --grid: #2c2c2a;
  --line: rgba(255, 255, 255, 0.10);
  --line-strong: rgba(255, 255, 255, 0.20);
  --accent: #3987e5;
  --accent-ink: #86b6ef;
  --accent-wash: rgba(57, 135, 229, 0.14);
  --accent-wash-2: rgba(57, 135, 229, 0.26);
  --good-ink: #0ca30c;
  --good-wash: rgba(12, 163, 12, 0.14);
  --bad-ink: #e66767;
  --bad-wash: rgba(208, 59, 59, 0.16);
  --warn-ink: #fab219;
  --warn-wash: rgba(250, 178, 25, 0.14);
  --m-new: #2c2c2a;
  --m-learning: #184f95;
  --m-reviewing: #2a78d6;
  --m-mastered: #6da7ec;
  --heat-0: #2c2c2a;
  --heat-1: #184f95;
  --heat-2: #256abf;
  --heat-3: #3987e5;
  --heat-4: #86b6ef;
  --other: #5c5b56;
  --shadow: none;
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.6);
  --scrim: rgba(0, 0, 0, 0.6);
}

/* ------------------------------------------------------------------ base */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font: 15px/1.5 var(--font);
  min-height: 100vh;
}
a { color: var(--accent-ink); text-decoration: none; }
a:hover { text-decoration: underline; }
a.small svg.icon, .small a svg.icon { width: 14px; height: 14px; vertical-align: -2px; }
code { font-family: var(--mono); font-size: 0.92em; padding: 1px 5px; border-radius: 5px; background: var(--fill); }
main:focus { outline: none; }
h1, h2, h3, h4 { margin: 0; line-height: 1.25; }
h1 { font-size: 24px; font-weight: 650; letter-spacing: -0.01em; }
h2 { font-size: 17px; font-weight: 620; }
h3 { font-size: 12px; font-weight: 650; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-2); }
p { margin: 0; }
button, input, select, textarea { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
svg.icon { width: 18px; height: 18px; flex: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.muted { color: var(--ink-2); }
.small { font-size: 13px; }
.num { font-variant-numeric: tabular-nums; }
.spacer { flex: 1; }
.row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.stack { display: grid; gap: 16px; align-content: start; }
.stack > .chip { justify-self: start; }

/* ------------------------------------------------------------------ top bar */

.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  height: var(--topbar);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); font-weight: 650; font-size: 16px; white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand-mark { width: 28px; height: 28px; border-radius: 8px; background: var(--btn); color: #fff; display: grid; place-items: center; }
.brand-mark svg { width: 18px; height: 18px; }
.exam-tabs { display: flex; gap: 4px; overflow-x: auto; scrollbar-width: none; }
.exam-tabs a {
  padding: 6px 12px;
  border-radius: 999px;
  color: var(--ink-2);
  font-weight: 560;
  font-size: 14px;
  white-space: nowrap;
}
.exam-tabs a:hover { background: var(--fill); text-decoration: none; }
.exam-tabs a.active { background: var(--accent-wash-2); color: var(--accent-ink); }
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 6px; }
.search { position: relative; }
.search svg { position: absolute; left: 10px; top: 50%; transform: translateY(-50%); color: var(--ink-3); pointer-events: none; width: 16px; height: 16px; }
.search input {
  width: 240px;
  height: 36px;
  padding: 0 34px 0 32px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--fill);
  outline: none;
}
.search input:focus { border-color: var(--accent); background: var(--raised); }
.search kbd { position: absolute; right: 10px; top: 50%; transform: translateY(-50%); }
.icon-btn {
  width: 36px;
  height: 36px;
  display: inline-grid;
  place-items: center;
  border-radius: 999px;
  border: 0;
  background: transparent;
  color: var(--ink-2);
  cursor: pointer;
}
.icon-btn:hover { background: var(--fill); color: var(--ink); text-decoration: none; }
kbd {
  display: inline-block;
  min-width: 20px;
  padding: 0 5px;
  border: 1px solid var(--line-strong);
  border-bottom-width: 2px;
  border-radius: 5px;
  font: 11px/16px var(--mono);
  color: var(--ink-2);
  text-align: center;
  background: var(--surface);
}

/* ------------------------------------------------------------------ page */

main { padding: 28px 20px 64px; }
.page { max-width: 1160px; margin: 0 auto; display: grid; grid-template-columns: minmax(0, 1fr); gap: 28px; }
.page-head { display: flex; align-items: flex-end; gap: 16px; flex-wrap: wrap; }
.page-head .sub { color: var(--ink-2); margin-top: 4px; }
.section { display: grid; gap: 12px; }
.section-head { display: flex; align-items: baseline; gap: 8px 12px; flex-wrap: wrap; }
.section-head .spacer + * { font-size: 13px; }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
}
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); gap: 16px; }

/* buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 38px;
  padding: 0 16px;
  border-radius: 10px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  color: var(--ink);
  font-weight: 560;
  font-size: 14px;
  cursor: pointer;
  white-space: nowrap;
  text-decoration: none;
}
.btn:hover { background: var(--fill); text-decoration: none; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn.primary { background: var(--btn); border-color: var(--btn); color: #fff; }
.btn.primary:hover { background: var(--btn-hover); border-color: var(--btn-hover); }
.btn.ghost { background: transparent; border-color: transparent; color: var(--ink-2); }
.btn.ghost:hover { background: var(--fill); color: var(--ink); }
.btn.good { border-color: var(--good); color: var(--good-ink); background: var(--good-wash); }
.btn.bad { border-color: var(--bad); color: var(--bad-ink); background: var(--bad-wash); }
.btn.sm { height: 32px; padding: 0 12px; font-size: 13px; border-radius: 8px; }
.btn.lg { height: 44px; padding: 0 20px; font-size: 15px; }
.btn kbd { margin-left: 2px; }
.btn.primary kbd { background: transparent; color: rgba(255, 255, 255, 0.85); border-color: rgba(255, 255, 255, 0.45); }
.btn .count { font-variant-numeric: tabular-nums; padding: 0 7px; border-radius: 999px; background: var(--fill); font-size: 12px; color: var(--ink-2); }
.btn.primary .count { background: rgba(255, 255, 255, 0.2); color: #fff; }

/* chips */
.chip {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  height: 24px;
  padding: 0 9px;
  border-radius: 999px;
  background: var(--fill);
  color: var(--ink-2);
  font-size: 12px;
  font-weight: 560;
  white-space: nowrap;
}
.chip svg { width: 13px; height: 13px; }
.chip.accent { background: var(--accent-wash-2); color: var(--accent-ink); }
.chip.good { background: var(--good-wash); color: var(--good-ink); }
.chip.bad { background: var(--bad-wash); color: var(--bad-ink); }
.chip.warn { background: var(--warn-wash); color: var(--warn-ink); }
.chip.code { font-family: var(--mono); font-weight: 600; letter-spacing: 0.02em; }

/* form controls */
.field { display: grid; gap: 6px; font-size: 13px; color: var(--ink-2); font-weight: 560; }
.field textarea { font-weight: 400; color: var(--ink); }
.field select, .field input[type="number"], .field input[type="text"], .field input[type="search"] {
  width: 100%;
  min-width: 0;
  height: 38px;
  padding: 0 10px;
  border-radius: 8px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  color: var(--ink);
  font-weight: 400;
  font-size: 14px;
}
.check { display: inline-flex; align-items: center; gap: 8px; font-size: 14px; cursor: pointer; }
.check input { width: 16px; height: 16px; accent-color: var(--btn); }
textarea.notes {
  width: 100%;
  min-height: 72px;
  resize: vertical;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  font-size: 14px;
  line-height: 1.5;
}
textarea.notes:focus { outline: none; border-color: var(--accent); }
.segmented { display: inline-flex; padding: 3px; gap: 2px; border-radius: 10px; background: var(--fill); }
.segmented button {
  border: 0;
  background: transparent;
  height: 30px;
  padding: 0 12px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 560;
  color: var(--ink-2);
  cursor: pointer;
}
.segmented button[aria-pressed="true"] { background: var(--raised); color: var(--ink); box-shadow: 0 1px 2px rgba(0, 0, 0, 0.12); }

/* ------------------------------------------------------------------ stat tiles & charts */

.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; }
.tile { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; box-shadow: var(--shadow); }
.tile .label { font-size: 13px; color: var(--ink-2); }
.tile .value { font-size: 28px; font-weight: 640; line-height: 1.2; margin-top: 4px; letter-spacing: -0.01em; }
.tile .value small { font-size: 15px; font-weight: 500; color: var(--ink-2); margin-left: 2px; }
.tile .hint { font-size: 12px; color: var(--ink-3); margin-top: 2px; }

.stackbar { display: flex; gap: 2px; height: 10px; width: 100%; }
.stackbar > span { height: 100%; min-width: 3px; }
.stackbar > span:first-child { border-radius: 4px 0 0 4px; }
.stackbar > span:last-child { border-radius: 0 4px 4px 0; }
.stackbar > span:only-child { border-radius: 4px; }
.stackbar > span:hover { filter: brightness(1.08); }
.legend { display: flex; flex-wrap: wrap; gap: 4px 14px; font-size: 12.5px; color: var(--ink-2); }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 10px; height: 10px; border-radius: 3px; display: inline-block; }
.legend b { color: var(--ink); font-weight: 600; font-variant-numeric: tabular-nums; }

.meter { height: 8px; border-radius: 4px; background: var(--accent-wash-2); overflow: hidden; }
.meter > span { display: block; height: 100%; background: var(--accent); border-radius: 0 4px 4px 0; }

.topic-rows { display: grid; gap: 14px; }
.topic-row { display: grid; grid-template-columns: minmax(0, 1fr) 120px 64px; gap: 6px 16px; align-items: center; }
.topic-row .name { font-weight: 560; }
.topic-row .meta { grid-column: 1 / -1; font-size: 12.5px; color: var(--ink-2); margin-top: -4px; }
.topic-row .acc { text-align: right; font-weight: 600; font-variant-numeric: tabular-nums; }

.heatmap-wrap { display: flex; gap: 8px; overflow-x: auto; padding-bottom: 4px; }
.heatmap-days { display: grid; grid-template-rows: repeat(7, 12px); gap: 2px; font-size: 10px; color: var(--ink-3); padding-top: 18px; }
.heatmap-days span { line-height: 12px; }
.heatmap { display: grid; grid-auto-flow: column; grid-auto-columns: 12px; grid-template-rows: 16px repeat(7, 12px); gap: 2px; }
.heatmap .month { font-size: 10px; color: var(--ink-3); white-space: nowrap; line-height: 16px; }
.heatmap .cell { width: 12px; height: 12px; border-radius: 3px; background: var(--heat-0); }
.heatmap .cell[data-l="1"] { background: var(--heat-1); }
.heatmap .cell[data-l="2"] { background: var(--heat-2); }
.heatmap .cell[data-l="3"] { background: var(--heat-3); }
.heatmap .cell[data-l="4"] { background: var(--heat-4); }
.heatmap .cell.future { background: transparent; }
.heatmap .cell:hover, .heatmap .cell:focus-visible { outline: 2px solid var(--ink); outline-offset: 0; }
.scale { display: inline-flex; align-items: center; gap: 2px; font-size: 11px; color: var(--ink-3); }
.scale i { width: 10px; height: 10px; border-radius: 2px; display: inline-block; }

.chart svg { display: block; width: 100%; height: auto; overflow: visible; }
.chart .gridline { stroke: var(--grid); stroke-width: 1; }
.chart .axis-label { fill: var(--ink-3); font-size: 11px; font-variant-numeric: tabular-nums; }
.chart .ref { stroke: var(--axis); stroke-width: 1; }
.chart .ref-label { fill: var(--ink-2); font-size: 11px; font-weight: 600; }
.chart .series { fill: none; stroke: var(--accent); stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.chart .dot { fill: var(--accent); stroke: var(--surface); stroke-width: 2; }
.chart .dot.active { r: 6; }
.chart .crosshair { stroke: var(--axis); stroke-width: 1; }
.data-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.data-table th, .data-table td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); }
.data-table th { color: var(--ink-2); font-weight: 600; font-size: 12px; }
.data-table td.n, .data-table th.n { text-align: right; font-variant-numeric: tabular-nums; }

#tooltip {
  position: fixed;
  z-index: 100;
  pointer-events: none;
  background: var(--raised);
  color: var(--ink);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-lg);
  border-radius: 8px;
  padding: 7px 10px;
  font-size: 12.5px;
  line-height: 1.4;
  max-width: 260px;
}
#tooltip strong { font-size: 14px; font-weight: 650; display: block; }
#tooltip .tip-sub { color: var(--ink-2); }

/* ------------------------------------------------------------------ home & exam pages */

.hero { display: flex; align-items: flex-end; gap: 24px; flex-wrap: wrap; }
.hero h1 { font-size: 28px; }
.exam-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(330px, 1fr)); gap: 16px; }
.exam-card { display: flex; flex-direction: column; gap: 16px; }
.exam-card-head { display: grid; gap: 6px; }
.exam-card-head a.title { color: var(--ink); font-size: 16.5px; font-weight: 620; line-height: 1.3; min-height: 2.6em; }
.exam-card-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.exam-card-stats div { display: grid; }
.exam-card-stats b { font-size: 18px; font-weight: 640; }
.exam-card-stats span { font-size: 12px; color: var(--ink-2); }
.card-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: auto; }

.quick-actions { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 10px; }
.qa {
  display: grid;
  grid-template-columns: 36px 1fr;
  gap: 2px 12px;
  align-items: center;
  padding: 14px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  text-align: left;
  box-shadow: var(--shadow);
}
.qa:hover { border-color: var(--accent); text-decoration: none; }
.qa:disabled { opacity: 0.5; cursor: not-allowed; border-color: var(--line); }
.qa .qa-icon { grid-row: span 2; width: 36px; height: 36px; border-radius: 10px; display: grid; place-items: center; background: var(--accent-wash-2); color: var(--accent-ink); }
.qa .qa-title { font-weight: 600; }
.qa .qa-sub { font-size: 12.5px; color: var(--ink-2); }
.qa.primary { background: var(--btn); border-color: var(--btn); color: #fff; }
.qa.primary .qa-icon { background: rgba(255, 255, 255, 0.18); color: #fff; }
.qa.primary .qa-sub { color: rgba(255, 255, 255, 0.85); }
.qa.primary:hover { background: var(--btn-hover); }

.builder { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; align-items: end; }
.linkish { background: none; border: 0; padding: 0; text-align: left; cursor: pointer; color: var(--ink); font-weight: 560; }
.linkish:hover { color: var(--accent-ink); text-decoration: underline; }
.option-card { display: grid; grid-template-columns: 20px 1fr; gap: 12px; align-items: start; padding: 14px 16px; border-radius: 10px; border: 1px solid var(--line-strong); background: var(--raised); cursor: pointer; }
.option-card input { margin: 3px 0 0; width: 16px; height: 16px; accent-color: var(--btn); }
.option-card .title { font-weight: 600; }
.option-card.active { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); background: var(--accent-wash); }
.row select { height: 38px; padding: 0 10px; border-radius: 8px; border: 1px solid var(--line-strong); background: var(--raised); }
.case-list { display: grid; gap: 8px; }
.case-item { display: flex; align-items: center; gap: 12px; padding: 10px 12px; border-radius: 10px; background: var(--fill); }
.case-item .name { font-weight: 600; }
.empty { padding: 28px; text-align: center; color: var(--ink-2); border: 1px dashed var(--line-strong); border-radius: var(--radius); }

/* ------------------------------------------------------------------ session layout */

.session { display: grid; grid-template-columns: 232px minmax(0, 1fr); gap: 24px; max-width: 1180px; margin: 0 auto; align-items: start; }
.session.case-open { grid-template-columns: 232px minmax(0, 1fr) minmax(360px, 460px); max-width: 1640px; }
.navigator {
  position: sticky;
  top: calc(var(--topbar) + 20px);
  max-height: calc(100vh - var(--topbar) - 40px);
  overflow: auto;
  display: grid;
  gap: 14px;
  align-content: start;
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.navigator .nav-title { font-weight: 620; line-height: 1.3; }
.navigator .nav-sub { font-size: 12.5px; color: var(--ink-2); }
.nav-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(32px, 1fr)); gap: 4px; }
.nav-grid button {
  position: relative;
  height: 30px;
  border-radius: 7px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  font-size: 12px;
  font-weight: 560;
  font-variant-numeric: tabular-nums;
  color: var(--ink-2);
  cursor: pointer;
  padding: 0;
}
.nav-grid button:hover { border-color: var(--accent); }
.nav-grid button.ok { background: var(--good-wash); border-color: var(--good); color: var(--good-ink); }
.nav-grid button.ko { background: var(--bad-wash); border-color: var(--bad); color: var(--bad-ink); }
.nav-grid button.answered { background: var(--accent-wash-2); border-color: var(--accent); color: var(--accent-ink); }
.nav-grid button.pending { border-color: var(--warn); color: var(--warn-ink); }
.nav-grid button.current { outline: 2px solid var(--ink); outline-offset: 1px; }
.nav-grid button.flagged::after {
  content: "";
  position: absolute;
  top: -3px;
  right: -3px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--warn);
  border: 2px solid var(--surface);
}
.nav-legend { display: grid; gap: 4px; font-size: 12px; color: var(--ink-2); }
.nav-legend span { display: inline-flex; align-items: center; gap: 6px; }
.nav-legend i { width: 12px; height: 12px; border-radius: 3px; border: 1px solid var(--line-strong); display: inline-block; }
.nav-toggle { display: none; }

.stage { min-width: 0; display: grid; gap: 16px; }
.session.done { grid-template-columns: minmax(0, 1fr); }

/* ------------------------------------------------------------------ question card */

.qcard { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.qcard-body { padding: 24px 28px 8px; display: grid; gap: 18px; }
.qmeta { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.qmeta .qnum { font-weight: 650; font-size: 15px; margin-right: 4px; }
.qmeta .pos { font-size: 13px; color: var(--ink-2); }
.flag-btn { margin-left: auto; }
.flag-btn[aria-pressed="true"] { color: var(--warn-ink); background: var(--warn-wash); }

.case-banner {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px 10px 14px;
  border-radius: 10px;
  background: var(--accent-wash);
  border: 1px solid var(--accent-wash-2);
}
.case-banner svg { color: var(--accent-ink); }
.case-banner .label { font-size: 12px; color: var(--ink-2); }
.case-banner .name { font-weight: 620; }

.rich { font-size: 16px; line-height: 1.65; overflow-wrap: anywhere; }
.rich p { margin: 0 0 12px; }
.rich p:last-child { margin-bottom: 0; }
.rich img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 10px 0 4px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #fff;
  cursor: zoom-in;
}
.rich table { border-collapse: collapse; margin: 8px 0; font-size: 14px; }
.rich td, .rich th { border: 1px solid var(--line-strong); padding: 6px 10px; vertical-align: top; }
.rich pre, .rich code { font-family: var(--mono); font-size: 13.5px; }
pre code { padding: 0; border-radius: 0; background: none; font-size: inherit; }
.rich pre { padding: 12px; background: var(--fill); border-radius: 8px; overflow-x: auto; }
.rich ul, .rich ol { margin: 0 0 12px; padding-left: 22px; }
.rich li { margin: 0 0 4px; padding-left: 2px; }
.rich li::marker { color: var(--ink-3); }
.rich ul.kv { list-style: none; padding-left: 0; display: grid; gap: 6px; }
.rich ul.kv li { margin: 0; padding: 0 0 0 14px; border-left: 2px solid var(--fill-2); }
.rich b, .rich strong { font-weight: 640; }
.rich h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--accent-ink); margin: 22px 0 8px; padding-top: 14px; border-top: 1px solid var(--line); }
.rich h4:first-child { margin-top: 0; padding-top: 0; border-top: 0; }
.rich h5 { font-size: 1em; font-weight: 650; margin: 16px 0 6px; color: var(--ink); }
.rich h4 + h5 { margin-top: 4px; }
.rich p.ask { margin-top: 16px; }
.rich p.ask strong { font-weight: 650; }
.rich p.note { font-size: 13.5px; color: var(--ink-2); }
.rich .exhibit { margin: 8px 0 14px; }
.rich pre.code-block, .area pre.code-area {
  margin: 0 0 12px;
  padding: 14px 16px;
  border-radius: 10px;
  background: var(--fill);
  border: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 13.5px;
  line-height: 1.6;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  overflow-x: auto;
}
.rich .table-wrap, .area .table-wrap { overflow-x: auto; margin: 0 0 12px; }
.rich .table-wrap table, .area .table-wrap table { margin: 0; }
.rich th { background: var(--fill); text-align: left; font-weight: 620; }
.rich .solution {
  margin: 4px 0 14px;
  padding: 12px 16px;
  border-left: 3px solid var(--accent);
  background: var(--accent-wash);
  border-radius: 0 10px 10px 0;
  font-weight: 560;
}
.rich .solution span {
  display: block;
  font-size: 11.5px;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent-ink);
  margin-bottom: 2px;
}

.pick-hint { font-size: 13px; color: var(--ink-2); font-weight: 560; display: flex; align-items: center; gap: 8px; }
.choices { display: grid; gap: 8px; }
.choice {
  position: relative;
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: start;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  cursor: pointer;
  font-size: 15.5px;
  line-height: 1.55;
  transition: border-color 0.12s, background-color 0.12s;
}
.choice:hover { border-color: var(--accent); }
.choice input { position: absolute; opacity: 0; pointer-events: none; }
.choice .letter {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: 1.5px solid var(--line-strong);
  display: grid;
  place-items: center;
  font-weight: 650;
  font-size: 13.5px;
  color: var(--ink-2);
  background: var(--surface);
}
.choice.multi .letter { border-radius: 8px; }
.choice .text { padding-top: 3px; overflow-wrap: anywhere; }
.choice .text img { max-width: 100%; height: auto; border-radius: 6px; background: #fff; }
.choice .mark { padding-top: 3px; display: flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 600; white-space: nowrap; }
.choice:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }
.choice.selected { border-color: var(--accent); background: var(--accent-wash); box-shadow: inset 0 0 0 1px var(--accent); }
.choice.selected .letter { background: var(--btn); border-color: var(--btn); color: #fff; }
.choice.locked { cursor: default; }
.choice.locked:hover { border-color: var(--line-strong); }
.choice.is-correct { border-color: var(--good); background: var(--good-wash); box-shadow: inset 0 0 0 1px var(--good); }
.choice.is-correct .letter { background: var(--good); border-color: var(--good); color: #fff; }
.choice.is-correct .mark { color: var(--good-ink); }
.choice.is-wrong { border-color: var(--bad); background: var(--bad-wash); box-shadow: inset 0 0 0 1px var(--bad); }
.choice.is-wrong .letter { background: var(--bad); border-color: var(--bad); color: #fff; }
.choice.is-wrong .mark { color: var(--bad-ink); }
.choice.is-missed { border-color: var(--good); box-shadow: inset 0 0 0 1px var(--good); }
.choice.is-missed .letter { border-color: var(--good); color: var(--good-ink); }
.choice.is-missed .mark { color: var(--good-ink); }
.choice.is-dim { opacity: 0.72; }
.choice .vote-tag { font-size: 11.5px; font-weight: 600; color: var(--ink-2); background: var(--fill); padding: 1px 7px; border-radius: 999px; }

/* interactive answer areas: drag & drop, ordering, drop-down menus, Yes/No grids */
.area { display: grid; gap: 12px; container: area / inline-size; }
.area-help { display: flex; align-items: flex-start; gap: 4px 8px; flex-wrap: wrap; font-size: 13px; font-weight: 560; color: var(--ink-2); line-height: 1.45; }
.area-help > svg { flex: none; width: 16px; height: 16px; margin-top: 1px; }
.area-help > span:first-of-type { flex: 1 1 220px; }
.area-help .spacer { display: none; }
.area-help .count { font-variant-numeric: tabular-nums; color: var(--ink-3); font-weight: 500; }
.area-split { display: grid; grid-template-columns: minmax(0, 1fr); gap: 14px; align-items: start; }
/* tiles sit above the answer area unless there is room for the exam's side-by-side panes */
.area-match .token-list { display: flex; flex-wrap: wrap; }
.area-match .token { width: auto; max-width: 100%; }
@container area (min-width: 1040px) {
  .area-match .area-split { grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); }
  .area-match .token-list { display: grid; }
  .area-match .token { width: 100%; }
}
@container area (min-width: 600px) {
  .area-order .area-split { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
}
.area-pane { display: grid; gap: 10px; align-content: start; padding: 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--surface); min-width: 0; }
.pane-title { font-size: 11.5px; font-weight: 650; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-2); }
.pane-sub { font-size: 12px; color: var(--ink-3); margin-top: -6px; }
.area-title { font-weight: 640; font-size: 15px; }
.area .area-heading, .area h5 { font-weight: 640; font-size: 14.5px; margin: 4px 0 0; }
.area .text-area { margin: 0; font-size: 15px; line-height: 2.2; }
.area .text-area + .text-area { margin-top: -4px; }
.pool { min-height: 96px; transition: background-color 0.12s, border-color 0.12s; }
.pool.drop-over { border-color: var(--accent); background: var(--accent-wash); }
.token-list { display: grid; gap: 8px; }

.token {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  min-height: 42px;
  padding: 8px 12px 8px 6px;
  border-radius: 9px;
  border: 1px solid var(--line-strong);
  background: var(--raised);
  box-shadow: var(--shadow);
  color: var(--ink);
  font: inherit;
  font-size: 14.5px;
  line-height: 1.4;
  text-align: left;
  cursor: grab;
  user-select: none;
  -webkit-user-select: none;
  transition: border-color 0.12s, background-color 0.12s, opacity 0.12s;
}
.token:hover { border-color: var(--accent); }
.token:focus-visible, .slot button:focus-visible, .yn-cell:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }
.token.armed, .slot.armed .placed { border-color: var(--accent); background: var(--accent-wash); box-shadow: inset 0 0 0 1px var(--accent); }
.token.used { opacity: 0.4; border-style: dashed; box-shadow: none; cursor: default; }
.token.used .token-text { text-decoration: line-through; text-decoration-color: var(--ink-3); }
.token.static { cursor: default; box-shadow: none; }
.token.static:hover { border-color: var(--line-strong); }
.token.dragging { opacity: 0.35; }
.token-text { min-width: 0; overflow-wrap: anywhere; }
.grip { flex: none; display: grid; place-items: center; width: 20px; height: 26px; color: var(--ink-3); touch-action: none; cursor: grab; }
.grip svg { width: 16px; height: 16px; }
.drag-ghost {
  position: fixed;
  left: 0;
  top: 0;
  z-index: 200;
  pointer-events: none;
  border-color: var(--accent);
  box-shadow: var(--shadow-lg);
  cursor: grabbing;
  rotate: -1.5deg;
}
.is-dragging, .is-dragging * { cursor: grabbing; }

.slot {
  position: relative;
  display: flex;
  align-items: stretch;
  gap: 2px;
  min-height: 44px;
  border-radius: 9px;
  border: 1.5px dashed var(--line-strong);
  background: var(--raised);
  transition: border-color 0.12s, background-color 0.12s;
}
.slot .drop {
  flex: 1;
  border: 0;
  background: none;
  font: inherit;
  font-size: 13.5px;
  color: var(--ink-3);
  text-align: left;
  padding: 8px 12px;
  border-radius: 8px;
  cursor: pointer;
}
.slot:hover, .slot.armed, .slot.drop-over { border-color: var(--accent); background: var(--accent-wash); }
.is-dragging .slot:not(.filled) { border-color: var(--accent); }
.slot.filled { border-style: solid; border-color: var(--line-strong); padding: 3px; }
.slot .placed {
  flex: 1;
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 8px 4px 2px;
  border: 1px solid transparent;
  border-radius: 7px;
  background: var(--fill);
  color: var(--ink);
  font: inherit;
  font-size: 14.5px;
  line-height: 1.4;
  text-align: left;
  cursor: grab;
  user-select: none;
  -webkit-user-select: none;
}
.slot .ctl {
  flex: none;
  width: 30px;
  border: 0;
  border-radius: 7px;
  background: none;
  color: var(--ink-3);
  display: grid;
  place-items: center;
  cursor: pointer;
}
.slot .ctl:hover:not(:disabled) { background: var(--fill-2); color: var(--ink); }
.slot .ctl:disabled { opacity: 0.3; cursor: default; }
.slot .ctl svg { width: 16px; height: 16px; }

/* boxes inside code or a sentence */
.slot.inline, .select-wrap.inline { display: inline-flex; vertical-align: middle; min-height: 32px; min-width: 150px; max-width: 100%; margin: 2px 0; }
.slot.inline .drop { padding: 4px 10px; font-size: 12.5px; }
.slot.inline .placed { font-size: 13.5px; padding: 2px 6px 2px 0; }
.code-area .slot.inline .placed, .code-area .slot.shown .val, .code-area select { font-family: var(--mono); font-size: 13px; }
.area pre.code-area { line-height: 2.1; margin: 0; }

/* answers once revealed */
.slot.shown { display: grid; gap: 2px; padding: 8px 12px; border-style: solid; font-size: 14.5px; line-height: 1.45; }
.slot.shown.inline { display: inline-grid; padding: 3px 10px; font-size: 13.5px; min-width: 0; }
.slot.shown .val-line { display: flex; align-items: flex-start; gap: 6px; }
.slot.shown .val-line svg { flex: none; width: 17px; height: 17px; margin-top: 2px; }
.slot.shown.is-correct { border-color: var(--good); background: var(--good-wash); }
.slot.shown.is-correct .val-line svg { color: var(--good); }
.slot.shown.is-wrong { border-color: var(--bad); background: var(--bad-wash); }
.slot.shown.is-wrong .val-line svg { color: var(--bad); }
.slot.shown.is-wrong .val { text-decoration: line-through; text-decoration-color: var(--bad); color: var(--ink-2); }
.slot.shown .val.none { font-style: italic; text-decoration: none; }
.slot.shown .fix { color: var(--good-ink); font-weight: 620; padding-left: 23px; }
.slot.shown.inline .fix { padding-left: 23px; }
.slot.shown .fix-label { font-weight: 500; color: var(--ink-2); }
.slot.shown.answer { border-color: var(--good); background: var(--good-wash); color: var(--ink); font-weight: 560; }
.other-key { display: block; font-size: 12px; font-weight: 500; color: var(--warn-ink); padding-left: 23px; }
.slot.shown.answer .other-key { padding-left: 0; }
.slot.shown .others { font-size: 12.5px; font-weight: 400; color: var(--ink-2); }

.rows { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr); gap: 10px 14px; align-items: center; }
.rows .th { font-size: 12px; font-weight: 650; color: var(--ink-2); padding-bottom: 2px; border-bottom: 1px solid var(--line); }
.row-label { font-size: 15px; line-height: 1.5; }
.row-box { min-width: 0; }

.seq { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.seq li { display: grid; grid-template-columns: 28px minmax(0, 1fr); gap: 10px; align-items: center; }
.seq .num { width: 28px; height: 28px; border-radius: 50%; background: var(--fill-2); color: var(--ink-2); font-weight: 650; font-size: 13px; display: grid; place-items: center; font-variant-numeric: tabular-nums; }

.area select {
  width: 100%;
  min-height: 42px;
  padding: 8px 10px;
  border-radius: 9px;
  border: 1.5px dashed var(--line-strong);
  background: var(--raised);
  color: var(--ink-3);
  font: inherit;
  font-size: 14.5px;
  cursor: pointer;
}
.area select.filled { border-style: solid; color: var(--ink); }
.area select:hover { border-color: var(--accent); }
.area select:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.select-wrap { display: block; min-width: 0; }
.select-wrap.inline select { min-height: 32px; padding: 3px 8px; font-size: 13px; }

.yn-wrap { overflow-x: auto; }
.yn { width: 100%; border-collapse: collapse; font-size: 15px; line-height: 1.5; }
.yn th { font-size: 12px; font-weight: 650; color: var(--ink-2); text-align: left; padding: 0 10px 6px; border-bottom: 1px solid var(--line); }
.yn th.c, .yn td.c { text-align: center; width: 64px; }
.yn td { padding: 10px; border-bottom: 1px solid var(--line); vertical-align: middle; }
.yn tr:last-child td { border-bottom: 0; }
.yn .stmt-in { display: grid; gap: 2px; }
.yn tr.is-correct td.stmt { box-shadow: inset 3px 0 0 var(--good); }
.yn tr.is-wrong td.stmt { box-shadow: inset 3px 0 0 var(--bad); }
.yn .fix { font-size: 13px; font-weight: 620; color: var(--bad-ink); }
.yn .other-key { padding-left: 0; }
.yn-cell { display: grid; place-items: center; width: 44px; height: 44px; margin: auto; border-radius: 10px; cursor: pointer; }
.yn-cell:hover { background: var(--accent-wash); }
.yn-cell input { position: absolute; opacity: 0; pointer-events: none; }
.yn-dot { width: 22px; height: 22px; border-radius: 50%; border: 2px solid var(--line-strong); background: var(--raised); display: inline-grid; place-items: center; vertical-align: middle; }
.yn-dot svg { width: 14px; height: 14px; }
.yn-cell input:checked + .yn-dot { border-color: var(--btn); box-shadow: inset 0 0 0 5px var(--btn); }
.yn-dot.is-key { border-color: var(--good); background: var(--good); color: #fff; }
.yn-dot.is-wrong { border-color: var(--bad); background: var(--bad); color: #fff; }

/* narrow answer areas (phones, or beside an open case study) */
@container area (max-width: 520px) {
  .rows { grid-template-columns: minmax(0, 1fr); gap: 6px; }
  .rows .th:nth-child(2) { display: none; }
  .row-box { margin-bottom: 10px; }
  .yn td { padding: 8px 6px; }
  .yn th.c, .yn td.c { width: 48px; }
}

/* review additions: locked series questions, pooled-variant chip, Learn links, study plan */
.lock-note { display: flex; align-items: flex-start; gap: 10px; padding: 10px 12px; border-radius: 10px; background: var(--fill); color: var(--ink-2); font-size: 13.5px; }
.lock-note svg { flex: none; width: 18px; height: 18px; margin-top: 1px; }
.area.locked { opacity: 0.6; }
.area.locked .token, .area.locked .slot .placed, .area.locked select { cursor: default; }
.nav-grid button.locked { border-style: dashed; opacity: 0.6; }
a.chip.variants { text-decoration: none; background: var(--accent-wash); color: var(--accent-ink); }
a.chip.variants:hover { background: var(--accent-wash-2); text-decoration: none; }
.terms { gap: 8px; }
.terms a.chip { text-decoration: none; height: 28px; padding: 0 11px; font-size: 12.5px; color: var(--ink); background: var(--raised); border: 1px solid var(--line-strong); }
.terms a.chip:hover { border-color: var(--accent); color: var(--accent-ink); text-decoration: none; }
.terms a.chip svg { width: 12px; height: 12px; color: var(--ink-3); }
.chip.muted { color: var(--ink-3); }
.plan .builder { grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); }
.plan-line { display: flex; align-items: center; gap: 6px; }
.plan-line svg { width: 14px; height: 14px; color: var(--ink-3); }

.key.reviewed { border-color: var(--accent-wash-2); background: var(--accent-wash); }
.key.reviewed.active { border-color: var(--accent); }
.key .small { margin-top: 4px; display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.chip.kp { background: var(--accent-wash); color: var(--accent-ink); max-width: 100%; white-space: normal; height: auto; min-height: 24px; padding: 2px 9px; }
.explain { display: grid; gap: 10px; padding: 14px 16px; border-radius: 10px; background: var(--fill); }
.explain p { margin: 0; font-size: 15px; line-height: 1.6; }
.explain .row { gap: 8px; }

details.originals { border: 1px solid var(--line); border-radius: 10px; padding: 10px 14px; background: var(--surface); }
details.originals summary { cursor: pointer; font-size: 13.5px; font-weight: 600; color: var(--ink-2); display: flex; align-items: center; gap: 8px; }
details.originals summary svg { width: 16px; height: 16px; }
details.originals[open] summary { margin-bottom: 10px; }
details.originals .rich { font-size: 14px; }

.selfgrade-box { display: grid; gap: 10px; padding: 14px 16px; border-radius: 10px; background: var(--fill); }
.selfgrade-box p { font-size: 14px; color: var(--ink-2); }

.actions {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 28px 20px;
  border-top: 1px solid var(--line);
  margin-top: 16px;
}
.actions .hint { font-size: 12px; color: var(--ink-3); }

.feedback { border-top: 1px solid var(--line); padding: 20px 28px 24px; display: grid; gap: 22px; }
.result {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-radius: 10px;
  font-weight: 620;
  flex-wrap: wrap;
}
.result svg { width: 22px; height: 22px; }
.result.good { background: var(--good-wash); color: var(--good-ink); }
.result.bad { background: var(--bad-wash); color: var(--bad-ink); }
.result.neutral { background: var(--fill); color: var(--ink); }
.result.partial { background: var(--warn-wash); color: var(--warn-ink); }
.result.selfgrade { display: grid; gap: 10px; justify-items: start; }
.result .detail { font-weight: 400; color: var(--ink-2); font-size: 14px; }
.result .spacer + .btn { font-weight: 560; }

.keys { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 10px; }
.key {
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--raised);
}
.key .label { font-size: 12px; color: var(--ink-2); display: flex; align-items: center; gap: 6px; }
.key .val { font-size: 20px; font-weight: 650; letter-spacing: 0.04em; font-family: var(--mono); }
.key.active { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.dispute-note { font-size: 13.5px; color: var(--ink-2); display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border-radius: 10px; background: var(--warn-wash); }
.dispute-note svg { color: var(--warn-ink); margin-top: 2px; }

.votes { display: grid; gap: 8px; }
.vote-row { display: grid; grid-template-columns: 52px minmax(0, 1fr) 104px; gap: 12px; align-items: center; font-size: 13.5px; }
.vote-row .ans { font-family: var(--mono); font-weight: 650; letter-spacing: 0.04em; }
.vote-row .track { height: 8px; }
.vote-row .fill { height: 8px; border-radius: 0 4px 4px 0; background: var(--other); min-width: 2px; }
.vote-row.top .fill { background: var(--accent); }
.vote-row .val { text-align: right; color: var(--ink-2); font-variant-numeric: tabular-nums; }
.vote-row .val b { color: var(--ink); font-weight: 650; }

.answer-media { display: grid; gap: 8px; }

.comments { display: grid; gap: 0; }
.comment { padding: 14px 0; border-top: 1px solid var(--line); display: grid; gap: 6px; }
.comment:first-child { border-top: 0; padding-top: 4px; }
.comment-head { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; font-size: 13px; color: var(--ink-2); }
.comment-head .user { font-weight: 620; color: var(--ink); }
.comment-head .up { margin-left: auto; display: inline-flex; align-items: center; gap: 4px; font-variant-numeric: tabular-nums; font-weight: 600; }
.comment-head .up svg { width: 14px; height: 14px; }
.comment-body { white-space: pre-wrap; font-size: 14.5px; line-height: 1.6; overflow-wrap: anywhere; }
.replies { margin: 6px 0 0 6px; padding-left: 14px; border-left: 2px solid var(--fill-2); }
.replies .comment { padding: 10px 0; }
.replies .comment:first-child { border-top: 0; }

/* case panel */
.case-panel {
  position: sticky;
  top: calc(var(--topbar) + 20px);
  max-height: calc(100vh - var(--topbar) - 40px);
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.case-panel[hidden] { display: none; }
.case-panel header { display: flex; align-items: center; gap: 10px; padding: 14px 16px; border-bottom: 1px solid var(--line); }
.case-panel header .name { font-weight: 650; }
.case-panel .case-scroll { overflow: auto; padding: 16px 18px 24px; }
.case-panel .rich { font-size: 14.5px; line-height: 1.6; }
.case-panel .rich p { margin-bottom: 10px; }
.scrim { display: none; }

/* session summary */
.summary { max-width: 760px; margin: 0 auto; display: grid; gap: 20px; }
.score-hero { display: flex; align-items: center; gap: 28px; flex-wrap: wrap; }
.score-hero .big { font-size: 56px; font-weight: 680; letter-spacing: -0.02em; line-height: 1; }
.score-hero .big small { font-size: 22px; font-weight: 560; color: var(--ink-2); }
.list { display: grid; }
.list-row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  padding: 10px 12px;
  border-top: 1px solid var(--line);
  color: var(--ink);
  text-align: left;
  background: transparent;
  border-left: 0;
  border-right: 0;
  border-bottom: 0;
  cursor: pointer;
  width: 100%;
}
.list-row:first-child { border-top: 0; }
.list-row:hover { background: var(--fill); text-decoration: none; }
.list-row .qn { font-weight: 650; font-variant-numeric: tabular-nums; color: var(--ink-2); }
.list-row .snippet { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.list-row .snippet mark { background: var(--warn-wash); color: inherit; border-radius: 3px; padding: 0 1px; }
.list-row .tags { display: flex; gap: 6px; align-items: center; }
.list-row .sub { font-size: 12.5px; color: var(--ink-2); margin-top: 2px; display: flex; gap: 8px; flex-wrap: wrap; }

/* mock exam */
.mockbar {
  position: sticky;
  top: var(--topbar);
  z-index: 20;
  margin: -28px -20px 24px;
  padding: 10px 20px;
  display: flex;
  align-items: center;
  gap: 14px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
.with-mockbar .navigator, .with-mockbar .case-panel { top: calc(var(--topbar) + 76px); max-height: calc(100vh - var(--topbar) - 96px); }
.timer { display: inline-flex; align-items: center; gap: 6px; font-weight: 650; font-variant-numeric: tabular-nums; font-size: 16px; padding: 4px 10px; border-radius: 8px; background: var(--fill); }
.timer.low { background: var(--warn-wash); color: var(--warn-ink); }
.timer.critical { background: var(--bad-wash); color: var(--bad-ink); }

/* dialogs */
dialog {
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 0;
  background: var(--surface);
  color: var(--ink);
  box-shadow: var(--shadow-lg);
  max-width: min(560px, calc(100vw - 32px));
}
dialog::backdrop { background: var(--scrim); }
.dialog-body { padding: 22px 24px; display: grid; gap: 12px; }
.dialog-actions { display: flex; justify-content: flex-end; gap: 8px; padding: 14px 24px 18px; }
.shortcuts { display: grid; grid-template-columns: auto 1fr; gap: 8px 16px; font-size: 14px; align-items: center; }
#lightbox { max-width: calc(100vw - 32px); max-height: calc(100vh - 32px); background: #fff; }
#lightbox .lb-scroll { overflow: auto; max-height: calc(100vh - 34px); }
#lightbox img { display: block; max-width: calc(100vw - 34px); height: auto; cursor: zoom-in; }
#lightbox.actual img { max-width: none; cursor: zoom-out; }
#lightbox .lb-close { position: fixed; top: 20px; right: 20px; background: var(--surface); box-shadow: var(--shadow-lg); }
.toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%);
  z-index: 120;
  padding: 10px 16px;
  border-radius: 10px;
  background: var(--ink);
  color: var(--page);
  font-size: 14px;
  box-shadow: var(--shadow-lg);
}
.banner { padding: 10px 14px; border-radius: 10px; background: var(--warn-wash); color: var(--ink); font-size: 14px; }

/* ------------------------------------------------------------------ responsive */

@media (max-width: 1279px) {
  .session.case-open { grid-template-columns: 232px minmax(0, 1fr); max-width: 1180px; }
  .case-panel {
    position: fixed;
    z-index: 50;
    top: var(--topbar);
    right: 0;
    bottom: 0;
    width: min(480px, 100vw);
    max-height: none;
    border-radius: 0;
    border-width: 0 0 0 1px;
    box-shadow: var(--shadow-lg);
  }
  .case-open .scrim { display: block; position: fixed; inset: var(--topbar) 0 0 0; background: var(--scrim); z-index: 45; }
}

@media (max-width: 860px) {
  .topbar { gap: 10px; padding: 0 12px; }
  .brand-name { display: none; }
  .search input { width: 150px; }
  .search kbd { display: none; }
  main { padding: 20px 16px 96px; }
  .session, .session.case-open { grid-template-columns: minmax(0, 1fr); }
  .navigator { position: static; max-height: none; display: none; }
  .navigator.open { display: grid; }
  .nav-toggle { display: flex; }
  .qcard-body { padding: 18px 16px 4px; }
  .feedback { padding: 18px 16px 20px; }
  .actions {
    position: sticky;
    bottom: 0;
    z-index: 10;
    padding: 12px 16px;
    background: var(--surface);
    border-radius: 0 0 var(--radius) var(--radius);
  }
  .actions .hint { display: none; }
  .mockbar { margin: -20px -16px 16px; padding: 8px 16px; }
  .vote-row { grid-template-columns: 44px minmax(0, 1fr) 84px; }
  .topic-row { grid-template-columns: minmax(0, 1fr) 80px 52px; }
  .rich { font-size: 15.5px; }
}

@media (max-width: 560px) {
  .exam-tabs { display: none; }
  .search input { width: 120px; }
  .exam-cards, .grid-2 { grid-template-columns: minmax(0, 1fr); }
  .exam-card-stats b { font-size: 16px; }
  .list-row { grid-template-columns: 44px minmax(0, 1fr); }
  .list-row .tags { grid-column: 2; }
  .actions .btn { padding: 0 12px; }
  .actions .btn .label-long { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}

/* ------------------------------------------------------------------ guide (Microsoft concept guide) */

.exam-tabs a.guide-tab { display: inline-flex; align-items: center; gap: 6px; }
.exam-tabs a.guide-tab svg { width: 15px; height: 15px; }
.guide-btn { display: none; }
.page.guide { max-width: 1100px; }
.guide-search {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 6px 6px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.guide-search svg { width: 18px; height: 18px; color: var(--ink-3); flex: none; }
.guide-search input { flex: 1; min-width: 0; border: 0; background: transparent; font-size: 16px; outline: none; color: var(--ink); }
.guide-search .btn { border-radius: 999px; }
.guide-chapters { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 14px; }
a.guide-chapter { display: grid; gap: 8px; align-content: start; color: var(--ink); }
a.guide-chapter:hover { border-color: var(--accent); text-decoration: none; }
a.guide-chapter h2 { font-size: 18px; margin: 2px 0 0; }
a.guide-chapter p { margin: 0; font-size: 14px; }
.guide-howto { margin: 0; padding-left: 20px; display: grid; gap: 8px; font-size: 14.5px; }
.guide-card { display: grid; gap: 14px; }
.guide-card h3 { margin: 0 0 4px; font-size: 18px; text-transform: none; letter-spacing: 0; color: var(--ink); }
.guide-card p { margin: 0; }
.guide-chips { gap: 6px; }
.guide-chips a.chip { text-decoration: none; }
.guide-chips a.chip:hover { background: var(--fill-2); text-decoration: none; }

.guide-layout { display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 28px; align-items: start; }
.guide-toc {
  position: sticky;
  top: calc(var(--topbar) + 20px);
  max-height: calc(100vh - var(--topbar) - 40px);
  overflow: auto;
  display: grid;
  gap: 18px;
  font-size: 13.5px;
}
.toc-group { display: grid; gap: 2px; }
.toc-title { font-size: 11.5px; font-weight: 650; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 4px; }
.guide-toc a { display: block; padding: 5px 10px; border-radius: 8px; color: var(--ink-2); border-left: 2px solid transparent; }
.guide-toc a:hover { background: var(--fill); text-decoration: none; color: var(--ink); }
.guide-toc a.active { color: var(--accent-ink); border-left-color: var(--accent); background: var(--accent-wash); }
.guide-toc a.current { color: var(--ink); font-weight: 600; }
.guide-body { display: grid; gap: 28px; min-width: 0; }
.guide-section { display: grid; gap: 12px; scroll-margin-top: calc(var(--topbar) + 16px); }
.guide-section > h2 { font-size: 22px; margin: 0; padding-top: 20px; border-top: 1px solid var(--line); }
.guide-section > h2 a { color: inherit; }
.guide-section > h2 a:hover { color: var(--accent-ink); text-decoration: none; }
.guide-prose { font-size: 15.5px; line-height: 1.75; }
.guide-prose > :first-child { margin-top: 0; }
.guide-prose p { margin: 0 0 12px; }
.guide-prose h4 { font-size: 16.5px; margin: 22px 0 8px; }
.guide-prose h5 { font-size: 15px; margin: 16px 0 6px; }
.guide-prose ul, .guide-prose ol { margin: 0 0 12px; padding-left: 22px; }
.guide-prose li { margin: 4px 0; }
.guide-prose li > ul, .guide-prose li > ol { margin: 4px 0 0; }
.guide-prose code { font: 13.5px/1.4 var(--mono); background: var(--fill); padding: 1px 5px; border-radius: 5px; }
.guide-prose pre.code-block { margin: 0 0 12px; }
.guide-prose strong { font-weight: 650; }
.guide-prose a { color: var(--accent-ink); }
.guide-prose p.refs { font-size: 13px; color: var(--ink-3); padding-left: 12px; border-left: 2px solid var(--line-strong); line-height: 1.6; }
.guide-prose p.refs a { color: var(--ink-2); }
.guide-prose .table-wrap { overflow-x: auto; margin: 0 0 14px; border: 1px solid var(--line); border-radius: 10px; }
.guide-prose table { border-collapse: collapse; width: 100%; font-size: 14px; line-height: 1.55; }
.guide-prose th, .guide-prose td { padding: 8px 12px; border-top: 1px solid var(--line); vertical-align: top; text-align: left; }
.guide-prose th { background: var(--fill); font-weight: 650; border-top: 0; white-space: nowrap; }
.callout { display: grid; gap: 4px; padding: 12px 16px; margin: 0 0 14px; border-radius: 10px; background: var(--fill); border-left: 3px solid var(--line-strong); }
.callout > p:last-child, .callout > ul:last-child, .callout > ol:last-child { margin-bottom: 0; }
.callout-label { font-size: 12px; font-weight: 700; letter-spacing: 0.08em; color: var(--ink-3); }
.callout.exam { background: var(--accent-wash); border-left-color: var(--accent); }
.callout.exam .callout-label { color: var(--accent-ink); }
.callout.confuse { background: var(--warn-wash); border-left-color: var(--warn); }
.callout.confuse .callout-label { color: var(--warn-ink); }
.callout.tip { background: var(--good-wash); border-left-color: var(--good); }
.callout.tip .callout-label { color: var(--good-ink); }
.callout.example { background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--line-strong); }
.callout.refs { background: transparent; padding: 4px 0 4px 12px; border-radius: 0; font-size: 13px; color: var(--ink-3); line-height: 1.6; }
.callout.refs a { color: var(--ink-2); }

/* term links and the explanation popover */
a.term, .term-hl { color: inherit; text-decoration: none; border-bottom: 1.5px dotted var(--accent); cursor: help; }
a.term:hover, .term-hl:hover, a.term:focus-visible, .term-hl:focus-visible { background: var(--accent-wash); color: var(--accent-ink); text-decoration: none; }
a.chip.term { text-decoration: none; border-bottom: 0; cursor: pointer; }
a.chip.term:hover { background: var(--accent-wash-2); color: var(--accent-ink); }
.term-hl.demo { cursor: default; }
.term-pop {
  position: fixed;
  z-index: 90;
  width: min(400px, calc(100vw - 16px));
  max-height: min(70vh, 540px);
  overflow: auto;
  padding: 14px 16px;
  border-radius: 12px;
  background: var(--raised);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-lg);
  display: grid;
  gap: 8px;
  font-size: 14px;
}
.term-pop[hidden] { display: none; }
.tp-head { display: flex; align-items: center; gap: 8px; }
.tp-head b { font-size: 16px; flex: 1; }
.tp-head .icon-btn { width: 28px; height: 28px; flex: none; }
.tp-zh { color: var(--ink-2); font-weight: 600; }
.tp-body.guide-prose { font-size: 14px; line-height: 1.65; }
.tp-body p:last-child, .tp-body ul:last-child { margin-bottom: 0; }
.tp-links { display: flex; flex-wrap: wrap; gap: 6px 14px; font-size: 13px; padding-top: 8px; border-top: 1px solid var(--line); }
.tp-links a { display: inline-flex; align-items: center; gap: 4px; }
.tp-links svg { width: 13px; height: 13px; }

/* diagrams */
.diagram { margin: 4px 0 18px; padding: 16px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); display: grid; gap: 10px; }
.diagram figcaption { font-size: 13px; font-weight: 650; color: var(--ink-2); }
.dg-layer { display: grid; gap: 6px; }
.dg-label { font-size: 12px; font-weight: 650; color: var(--ink-3); letter-spacing: 0.04em; }
.dg-boxes { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 8px; }
.dg-box { padding: 10px 12px; border-radius: 10px; background: var(--fill); border: 1px solid var(--line); display: grid; gap: 2px; font-size: 13.5px; line-height: 1.45; }
.dg-box b { font-weight: 650; }
.dg-box span { color: var(--ink-2); font-size: 12.5px; }
.dg-box.hi { background: var(--accent-wash); border-color: var(--accent-wash-2); }
.dg-arrow { display: flex; align-items: center; gap: 8px; color: var(--ink-3); font-size: 12.5px; }
.dg-arrow::before { content: ''; width: 2px; height: 18px; background: var(--line-strong); margin-left: 18px; }
.dg-cols { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 10px; }
.dg-col { border: 1px solid var(--line); border-radius: 10px; overflow: hidden; background: var(--fill); }
.dg-col-head { padding: 10px 12px; background: var(--accent-wash); display: grid; gap: 2px; }
.dg-col-head b { font-size: 14px; }
.dg-col-head span { font-size: 12px; color: var(--ink-2); }
.dg-col ul { margin: 0; padding: 8px 12px 10px 28px; font-size: 13.5px; display: grid; gap: 3px; }
.dg-flow { display: flex; flex-wrap: wrap; align-items: stretch; gap: 6px; }
.dg-step { flex: 1 1 140px; padding: 10px 12px; border-radius: 10px; background: var(--fill); border: 1px solid var(--line); display: grid; gap: 2px; font-size: 13.5px; }
.dg-step span { color: var(--ink-2); font-size: 12.5px; }
.dg-next { align-self: center; width: 0; height: 0; border: 7px solid transparent; border-left: 10px solid var(--line-strong); border-right: 0; }

/* glossary */
.gloss-letters { display: flex; flex-wrap: wrap; gap: 4px; }
.gloss-letters a { min-width: 30px; height: 30px; padding: 0 6px; display: inline-grid; place-items: center; border-radius: 8px; background: var(--fill); color: var(--ink-2); font-weight: 600; font-size: 13px; }
.gloss-letters a:hover { background: var(--accent-wash-2); color: var(--accent-ink); text-decoration: none; }
.gloss-list { display: grid; gap: 24px; }
.gloss-group { display: grid; gap: 10px; scroll-margin-top: calc(var(--topbar) + 16px); }
.gloss-letter { font-size: 13px; font-weight: 700; color: var(--ink-3); letter-spacing: 0.1em; padding-bottom: 4px; border-bottom: 1px solid var(--line); }
.gloss-entry { display: grid; gap: 8px; padding: 16px 18px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); scroll-margin-top: calc(var(--topbar) + 16px); }
.gloss-entry.focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-wash-2); }
.gloss-head { display: flex; align-items: baseline; gap: 6px 12px; flex-wrap: wrap; }
.gloss-head h3 { margin: 0; font-size: 17px; text-transform: none; letter-spacing: 0; color: var(--ink); }
.gloss-zh { color: var(--ink-2); font-weight: 600; }
.gloss-entry .guide-prose { font-size: 14.5px; line-height: 1.7; }
.gloss-entry .guide-prose p:last-child { margin-bottom: 0; }
.gloss-links { gap: 6px 14px; align-items: center; }
.gloss-links a { display: inline-flex; align-items: center; gap: 4px; }
.gloss-links a.chip { text-decoration: none; }
.gloss-links svg { width: 13px; height: 13px; }
.gloss-hits { gap: 6px; align-items: center; }
.practice-qa { cursor: default; }
.practice-qa .qa-title { font: inherit; font-weight: 600; text-align: left; padding: 0; }
.guide-nav { display: flex; gap: 10px; flex-wrap: wrap; padding-top: 20px; border-top: 1px solid var(--line); }

@media (max-width: 860px) {
  .guide-layout { grid-template-columns: minmax(0, 1fr); gap: 16px; }
  .guide-toc { position: static; max-height: none; display: flex; gap: 6px; overflow-x: auto; padding-bottom: 4px; scrollbar-width: none; }
  .guide-toc .toc-group { display: flex; gap: 6px; align-items: center; }
  .guide-toc .toc-group:last-child { display: none; }
  .guide-toc .toc-title { display: none; }
  .guide-toc a { white-space: nowrap; border-left: 0; background: var(--fill); padding: 6px 12px; border-radius: 999px; }
  .guide-toc a.active { background: var(--accent-wash-2); }
  .guide-section > h2 { font-size: 20px; }
}

@media (max-width: 560px) {
  .guide-btn { display: inline-grid; }
  .guide-search { padding-left: 12px; }
  .guide-search .btn { padding: 0 12px; }
}

/* Phones: a vertical-stack grid with an implicit `auto` column grows to the min-content width of its
   widest child (a table with nowrap headers, a diagram row), overflowing the viewport while the top bar
   stays viewport-wide. One explicit column that may shrink keeps every guide block inside its parent. */
.guide-body, .guide-section, .guide-card, a.guide-chapter, .toc-group, .callout, .diagram, .dg-layer,
.dg-box, .dg-col-head, .dg-step, .gloss-list, .gloss-group, .gloss-entry, .term-pop { grid-template-columns: minmax(0, 1fr); }
.guide-prose, .dg-box, .dg-col, .dg-step, .gloss-head, .tp-body, .diagram figcaption { min-width: 0; overflow-wrap: break-word; }
.guide-prose code { overflow-wrap: anywhere; }
@media (max-width: 560px) {
  .guide-prose th { white-space: normal; }
}

/* official skills measured (exam page) */
details.skill-group { border: 1px solid var(--line); border-radius: 10px; background: var(--surface); }
details.skill-group > summary { list-style: none; cursor: pointer; display: grid; grid-template-columns: minmax(0, 1fr) 120px 64px; gap: 6px 16px; align-items: center; padding: 12px 14px; }
details.skill-group > summary::-webkit-details-marker { display: none; }
details.skill-group > summary .name { font-weight: 600; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; min-width: 0; }
details.skill-group > summary .name-text { flex: 1 1 160px; min-width: 0; }
details.skill-group > summary .name > svg { width: 16px; height: 16px; flex: none; color: var(--ink-3); transition: transform 0.15s; }
details.skill-group[open] > summary .name > svg { transform: rotate(180deg); }
details.skill-group > summary .meta { grid-column: 1 / -1; font-size: 12.5px; color: var(--ink-2); margin-top: -4px; }
details.skill-group > summary .acc { text-align: right; font-weight: 600; font-variant-numeric: tabular-nums; }
.skill-area { padding: 8px 14px 12px; border-top: 1px solid var(--line); }
.skill-area-head { display: flex; align-items: center; gap: 8px 12px; flex-wrap: wrap; margin: 6px 0 4px; font-weight: 600; }
.obj-row { display: flex; align-items: flex-start; gap: 10px; padding: 8px 0; border-top: 1px dashed var(--line); }
.obj-row:first-of-type { border-top: 0; }
.obj-id { font-family: var(--mono); font-size: 12px; color: var(--ink-3); padding-top: 3px; flex: none; min-width: 34px; }
.obj-main { min-width: 0; flex: 1; display: grid; gap: 2px; }
.obj-text { font-size: 14px; }
.obj-zh { font-size: 12.5px; color: var(--ink-2); }
.obj-links { display: flex; gap: 12px; font-size: 12.5px; margin-top: 2px; }
.obj-links a { display: inline-flex; align-items: center; gap: 3px; }
.obj-links svg { width: 13px; height: 13px; }
.obj-row.gap .obj-text { color: var(--ink-2); }
.obj-row > .btn, .obj-row > .chip { flex: none; }
.chip.obj { background: var(--fill); color: var(--ink-2); max-width: 100%; white-space: normal; height: auto; min-height: 24px; padding: 2px 9px; }
@media (max-width: 520px) {
  details.skill-group > summary { grid-template-columns: minmax(0, 1fr) 56px; }
  details.skill-group > summary .meter { display: none; }
  .obj-row { flex-wrap: wrap; }
  .obj-row > .btn, .obj-row > .chip { margin-left: 44px; }
}
.skill-practice { margin: -4px 0 12px; padding: 8px 12px; border-radius: 10px; background: var(--fill); }
button.chip.obj { cursor: pointer; font: inherit; border: 1px solid transparent; text-align: left; }
button.chip.obj:hover { background: var(--accent-wash); color: var(--accent-ink); }