/* Design idea: the exam paper itself. White sheets on a cool desk, Arial question text
   like a real paper, marks in the right margin, and red-pen marking as the one accent. */

:root {
  --desk: #E9EDF2;
  --sheet: #FFFFFF;
  --ink: #15233F;
  --ink-soft: #4E5A70;
  --rule: #C9D1DD;
  --pen: #C4122F;
  --pen-soft: #FBE7EA;
  --hi: #FFE45E;
  --ok: #17734A;
  --radius: 6px;
  --paper-font: Arial, "Helvetica Neue", Helvetica, sans-serif;
  --ui-font: "Segoe UI", "Helvetica Neue", Roboto, system-ui, sans-serif;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --desk: #0F1726;
    --sheet: #18233A;
    --ink: #E8EDF5;
    --ink-soft: #A7B2C6;
    --rule: #34425E;
    --pen: #FF5A6E;
    --pen-soft: #3A1E2A;
    --hi: #6B5A00;
    --ok: #4CC38A;
    color-scheme: dark;
  }
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--desk);
  color: var(--ink);
  font: 17px/1.55 var(--ui-font);
}
img, svg { max-width: 100%; }
a { color: inherit; text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--pen); outline-offset: 2px; border-radius: 3px; }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 12px; background: var(--sheet); padding: 8px 12px; z-index: 10; }

.wrap { width: min(1120px, 100% - 32px); margin-inline: auto; }
.narrow { width: min(760px, 100% - 32px); margin-inline: auto; }

/* Header */
.site-header { padding: 18px 0; }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.brand { font-weight: 800; font-size: 1.25rem; letter-spacing: -0.02em; text-decoration: none; display: inline-flex; align-items: center; gap: 10px; }
.brand-mark { width: 26px; height: 26px; color: var(--pen); }
.nav { display: flex; gap: 20px; font-size: 0.95rem; }
.nav a { text-decoration: none; color: var(--ink-soft); }
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); text-decoration: underline; }

/* Type */
h1, h2, h3 { line-height: 1.12; letter-spacing: -0.025em; margin: 0 0 0.5em; }
h1 { font-size: clamp(2.1rem, 4.6vw, 3.5rem); font-weight: 800; }
h2 { font-size: clamp(1.45rem, 2.6vw, 1.9rem); font-weight: 750; }
h3 { font-size: 1.15rem; font-weight: 700; letter-spacing: -0.01em; }
p { margin: 0 0 1em; }
.lead { font-size: 1.15rem; color: var(--ink-soft); max-width: 34em; }
.muted { color: var(--ink-soft); }
.small { font-size: 0.88rem; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font: 600 1rem/1 var(--ui-font); padding: 13px 20px; border-radius: var(--radius);
  border: 2px solid var(--ink); background: var(--ink); color: var(--sheet);
  text-decoration: none; cursor: pointer;
}
.btn:hover { background: transparent; color: var(--ink); }
.btn.secondary { background: transparent; color: var(--ink); }
.btn.secondary:hover { background: var(--ink); color: var(--sheet); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* Sheet: the exam paper surface */
.sheet {
  background: var(--sheet);
  border-radius: 3px;
  box-shadow: 0 1px 0 var(--rule), 0 12px 30px -18px rgba(21, 35, 63, 0.45);
}

/* Hero */
.hero { padding: 40px 0 72px; }
.hero .wrap { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 56px; align-items: center; }
.hero h1 { max-width: 13em; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 28px; }
.hero-paper { padding: 26px 28px 30px; transform: rotate(0.8deg); font-family: var(--paper-font); position: relative; }
.paper-head { display: flex; justify-content: space-between; font-size: 0.8rem; color: var(--ink-soft); border-bottom: 1px solid var(--rule); padding-bottom: 10px; margin-bottom: 20px; }
@media (max-width: 860px) {
  .hero .wrap { grid-template-columns: 1fr; gap: 36px; }
  .hero-paper { transform: none; }
}

/* A question as it looks on a paper */
.q { display: grid; grid-template-columns: 2.4em 1fr; gap: 0 10px; font-family: var(--paper-font); }
.q-num { font-weight: 700; font-size: 1.05rem; }
.q-body > .q-stem { margin-bottom: 14px; }
.part { padding: 6px 0 18px; }
.part + .part { border-top: 1px dashed var(--rule); padding-top: 16px; }
.part-label { font-weight: 700; margin-right: 6px; }
.part-prompt { margin: 0 0 12px; }
.answer-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; justify-content: flex-end; }
.answer-row .affix { font-weight: 600; }
.answer-input {
  font: 1.05rem/1.2 var(--paper-font); color: var(--ink);
  background: transparent; border: none; border-bottom: 2px dotted var(--ink-soft);
  padding: 8px 4px; width: min(240px, 100%); text-align: center;
}
.answer-input:focus { outline: none; border-bottom: 2px solid var(--ink); background: color-mix(in srgb, var(--hi) 35%, transparent); }
.marks-tag { font-size: 0.9rem; color: var(--ink-soft); white-space: nowrap; min-width: 4.6em; text-align: right; }
.choices { display: flex; gap: 10px; flex-wrap: wrap; justify-content: flex-end; }
.choice { position: relative; }
.choice input { position: absolute; opacity: 0; inset: 0; cursor: pointer; }
.choice span { display: inline-block; min-width: 3.4em; text-align: center; padding: 8px 12px; border: 1.5px solid var(--rule); border-radius: 4px; font: 1rem var(--paper-font); }
.choice input:checked + span { border-color: var(--ink); background: var(--ink); color: var(--sheet); }
.choice input:focus-visible + span { outline: 3px solid var(--pen); outline-offset: 2px; }
.figure { color: var(--ink); max-width: 240px; margin: 4px 0 14px; }

/* Red-pen marking */
.pen { font-family: "Segoe Print", "Bradley Hand", "Comic Sans MS", cursive; color: var(--pen); font-weight: 700; }
.verdict { display: none; margin-top: 12px; padding: 12px 14px; border-left: 3px solid var(--pen); background: var(--pen-soft); border-radius: 0 4px 4px 0; font-family: var(--ui-font); font-size: 0.95rem; }
.marked .verdict { display: block; }
.verdict .pen { font-size: 1.15rem; margin-right: 8px; }
.verdict p { margin: 6px 0 0; }
.part.right .verdict { border-left-color: var(--ok); background: color-mix(in srgb, var(--ok) 10%, var(--sheet)); }
.part.right .verdict .pen { color: var(--ok); }
.score-mark { display: none; }
.marked .score-mark { display: inline; }
.marked .answer-input, .marked .choice input { pointer-events: none; }

/* Hero demo */
.demo-result { min-height: 1.6em; margin-top: 16px; font-family: var(--ui-font); font-size: 0.95rem; }
.demo-result .pen { font-size: 1.6rem; vertical-align: -3px; margin-right: 6px; }

/* Sections */
.section { padding: 56px 0; }
.section-head { display: flex; justify-content: space-between; align-items: baseline; gap: 16px; flex-wrap: wrap; margin-bottom: 22px; }

/* Mock list */
.mock-row { display: grid; grid-template-columns: 1fr auto; gap: 18px; align-items: center; padding: 22px 26px; text-decoration: none; }
.mock-row + .mock-row { margin-top: 12px; }
.mock-row h3 { margin-bottom: 4px; }
.mock-meta { display: flex; gap: 16px; flex-wrap: wrap; font-size: 0.9rem; color: var(--ink-soft); }
.mock-row:hover h3 { text-decoration: underline; }
@media (max-width: 600px) { .mock-row { grid-template-columns: 1fr; } }

/* Subject index */
.subject-groups { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 36px 40px; }
.subject-group h3 { color: var(--ink-soft); font-size: 0.95rem; font-weight: 600; letter-spacing: 0; border-bottom: 2px solid var(--ink); padding-bottom: 8px; }
.subject-list { list-style: none; margin: 0; padding: 0; }
.subject-list li { border-bottom: 1px solid var(--rule); }
.subject-list a { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 11px 2px; text-decoration: none; }
.subject-list a:hover .name { text-decoration: underline; }
.status { font-size: 0.8rem; color: var(--ink-soft); white-space: nowrap; }
.status.live { color: var(--pen); font-weight: 700; }

/* Steps */
.steps { list-style: none; counter-reset: step; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.steps li { counter-increment: step; }
.steps li::before { content: counter(step); display: block; font: 700 2.4rem/1 var(--paper-font); color: var(--pen); margin-bottom: 10px; }
@media (max-width: 760px) { .steps { grid-template-columns: 1fr; gap: 22px; } }

/* Subject page */
.crumbs { font-size: 0.88rem; color: var(--ink-soft); margin-bottom: 18px; }
.crumbs a { color: var(--ink-soft); }
.page-head { padding: 28px 0 36px; }
.boards { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 0; padding: 0; list-style: none; }
.boards li { border: 1.5px solid var(--rule); border-radius: 999px; padding: 4px 12px; font-size: 0.88rem; }
.topics { columns: 2 260px; padding-left: 1.2em; margin: 0; }
.topics li { margin-bottom: 6px; break-inside: avoid; }
.empty { padding: 26px 28px; }

/* Exam page */
.exam-bar { position: sticky; top: 0; z-index: 5; background: color-mix(in srgb, var(--desk) 92%, transparent); backdrop-filter: blur(6px); border-bottom: 1px solid var(--rule); }
.exam-bar .wrap { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px 0; flex-wrap: wrap; }
.timer { font: 700 1.35rem/1 var(--paper-font); font-variant-numeric: tabular-nums; min-width: 4.5em; }
.timer.low { color: var(--pen); }
.bar-actions { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.bar-actions .btn { padding: 10px 16px; font-size: 0.95rem; }
.exam-cover { padding: 30px 34px; margin: 26px 0; font-family: var(--paper-font); }
.exam-cover h1 { font-family: var(--ui-font); font-size: clamp(1.7rem, 3.4vw, 2.4rem); }
.cover-facts { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); padding: 14px 0; margin: 18px 0; }
.cover-facts dt { font-size: 0.8rem; color: var(--ink-soft); }
.cover-facts dd { margin: 0; font-weight: 700; font-size: 1.1rem; }
.cover-instructions { padding-left: 1.2em; margin: 0; }
.cover-instructions li { margin-bottom: 6px; }
.paper { padding: 10px 34px; }
.paper .q { padding: 26px 0 8px; border-bottom: 1px solid var(--rule); }
.paper .q:last-child { border-bottom: none; }
.q-topic { font: 0.78rem var(--ui-font); color: var(--ink-soft); }
.end-paper { text-align: center; padding: 26px 0 40px; font-family: var(--paper-font); font-weight: 700; letter-spacing: 0.08em; color: var(--ink-soft); }
@media (max-width: 600px) {
  .exam-bar .wrap { padding: 8px 0; }
  .bar-actions .btn { padding: 8px 12px; font-size: 0.9rem; }
  .timer { font-size: 1.15rem; }
  .paper { padding: 4px 18px; }
  .exam-cover { padding: 22px 20px; }
  .q { grid-template-columns: 1.8em 1fr; }
}

/* Results */
.results { display: none; padding: 30px 34px; margin: 26px 0; }
.results.show { display: block; scroll-margin-top: 84px; }
.score-line { display: flex; align-items: baseline; gap: 22px; flex-wrap: wrap; margin-bottom: 8px; }
.score-big { font: 700 clamp(2.6rem, 7vw, 4rem)/1 var(--paper-font); color: var(--pen); }
.grade-big { font: 700 1.4rem/1.2 var(--ui-font); }
.topic-table { width: 100%; border-collapse: collapse; margin: 18px 0 10px; font-size: 0.95rem; }
.topic-table th, .topic-table td { text-align: left; padding: 9px 6px; border-bottom: 1px solid var(--rule); }
.topic-table td:last-child, .topic-table th:last-child { text-align: right; }
.topic-bar { height: 6px; background: var(--rule); border-radius: 3px; overflow: hidden; min-width: 80px; }
.topic-bar span { display: block; height: 100%; background: var(--ink); }

/* Prose pages */
.prose { padding: 30px 34px; margin-bottom: 60px; }
.prose h2 { margin-top: 1.4em; }

/* Footer */
.site-footer { padding: 40px 0 50px; font-size: 0.88rem; color: var(--ink-soft); border-top: 1px solid var(--rule); margin-top: 40px; }
.site-footer .wrap { display: grid; grid-template-columns: 1fr auto; gap: 18px 40px; }
.site-footer nav { display: flex; gap: 18px; flex-wrap: wrap; }
@media (max-width: 700px) { .site-footer .wrap { grid-template-columns: 1fr; } }

@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }
@media print {
  .site-header, .site-footer, .exam-bar, .results { display: none !important; }
  body { background: #fff; }
  .sheet { box-shadow: none; }
}

/* ===================================================================
   Phone: app layout
   =================================================================== */
.tabbar, .pager, .exit-link, .mobile-only, .mobile-inline { display: none; }
.btn.block { width: 100%; }
.cover-start { margin: 22px 0 0; }
.qnav { display: none; }

html { -webkit-tap-highlight-color: transparent; }

@media (max-width: 700px) {
  :root { --app-gap: 12px; --tab-h: 62px; }
  .desk-only { display: none !important; }
  .mobile-only { display: block; }
  .mobile-inline { display: inline; }
  body { font-size: 16px; padding-bottom: calc(var(--tab-h) + env(safe-area-inset-bottom)); overscroll-behavior-y: none; }
  .wrap, .narrow { width: calc(100% - 2 * var(--app-gap)); }

  /* App header */
  .site-header {
    position: sticky; top: 0; z-index: 20; padding: calc(10px + env(safe-area-inset-top)) 0 10px;
    background: color-mix(in srgb, var(--desk) 88%, transparent);
    backdrop-filter: saturate(1.4) blur(12px); -webkit-backdrop-filter: saturate(1.4) blur(12px);
    border-bottom: 1px solid color-mix(in srgb, var(--rule) 70%, transparent);
  }
  .site-header .nav { display: none; }
  .brand { font-size: 1.1rem; }
  .brand-mark { width: 24px; height: 24px; }

  /* Bottom tab bar */
  .tabbar {
    display: grid; grid-template-columns: repeat(4, 1fr);
    position: fixed; left: 0; right: 0; bottom: 0; z-index: 30;
    height: calc(var(--tab-h) + env(safe-area-inset-bottom)); padding-bottom: env(safe-area-inset-bottom);
    background: color-mix(in srgb, var(--sheet) 92%, transparent);
    backdrop-filter: saturate(1.4) blur(14px); -webkit-backdrop-filter: saturate(1.4) blur(14px);
    border-top: 1px solid var(--rule);
  }
  .tabbar a { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 3px; text-decoration: none; color: var(--ink-soft); font-size: 0.7rem; font-weight: 600; }
  .tabbar svg { width: 25px; height: 25px; }
  .tabbar a[aria-current="page"] { color: var(--pen); }
  .tabbar a:active { transform: scale(0.94); }

  /* Surfaces become app cards */
  .sheet { border-radius: 16px; box-shadow: 0 1px 2px rgba(21, 35, 63, 0.06); }
  h1 { font-size: 2rem; }
  h2 { font-size: 1.3rem; }
  .lead { font-size: 1rem; }
  .btn { min-height: 48px; border-radius: 12px; }
  .btn:hover { background: var(--ink); color: var(--sheet); }
  .btn.secondary:hover { background: transparent; color: var(--ink); }
  .btn:active { transform: scale(0.98); }

  /* Home */
  .hero { padding: 18px 0 8px; }
  .hero .wrap { gap: 18px; }
  .hero h1 { font-size: 2.05rem; }
  .hero-actions { margin-top: 18px; }
  .hero-actions { flex-direction: column; }
  .hero-actions .btn { width: 100%; }
  .hero-paper { padding: 18px; }
  .section { padding: 26px 0; }
  .section-head { margin-bottom: 12px; }
  .section-head h2 { margin: 0; }
  .section-head a { font-weight: 600; text-decoration: none; color: var(--pen); font-size: 0.95rem; }

  /* Mock rows become list cells */
  .mock-row { grid-template-columns: 1fr auto; padding: 16px; gap: 12px; }
  .mock-row .btn { display: none; }
  .mock-row::after { content: ""; width: 9px; height: 9px; border-right: 2px solid var(--ink-soft); border-top: 2px solid var(--ink-soft); transform: rotate(45deg); }
  .mock-row h3 { font-size: 1rem; }
  .mock-meta { gap: 4px 12px; font-size: 0.82rem; }
  .mock-row:active { background: color-mix(in srgb, var(--rule) 30%, var(--sheet)); }

  /* Steps: compact */
  .steps li { display: grid; grid-template-columns: 34px 1fr; column-gap: 12px; }
  .steps li::before { font-size: 1.6rem; margin: 0; grid-row: span 2; }
  .steps h3 { margin-bottom: 2px; }
  .steps p { margin: 0; font-size: 0.95rem; }

  /* Subject lists: inset grouped lists like iOS settings */
  .subject-groups { grid-template-columns: 1fr; gap: 20px; }
  .subject-group h3 { border: 0; padding: 0 4px 6px; margin: 0; font-size: 0.82rem; }
  .subject-list { background: var(--sheet); border-radius: 16px; overflow: hidden; }
  .subject-list li { border-bottom: 1px solid var(--rule); }
  .subject-list li:last-child { border-bottom: 0; }
  .subject-list a { padding: 14px 16px; min-height: 52px; }
  .subject-list a::after { content: ""; flex: none; width: 8px; height: 8px; border-right: 2px solid var(--rule); border-top: 2px solid var(--rule); transform: rotate(45deg); margin-left: -4px; }
  .subject-list a:active { background: color-mix(in srgb, var(--rule) 30%, var(--sheet)); }
  .subject-list .status { margin-left: auto; }

  /* Subject + content pages */
  .page-head { padding: 14px 0 18px; }
  .crumbs { display: none; }
  .topics { columns: 1; background: var(--sheet); border-radius: 16px; padding: 10px 16px 10px 34px; }
  .topics li { padding: 6px 0; margin: 0; }
  .prose { padding: 20px; margin: 12px 0 24px; }

  /* Footer: quiet */
  .site-footer { margin-top: 12px; padding: 22px 0 28px; font-size: 0.8rem; }

  /* ---------- Exam: focus mode ---------- */
  .exam-page { padding-bottom: calc(76px + env(safe-area-inset-bottom)); }
  .exam-page .site-header, .exam-page .tabbar, .exam-page .site-footer { display: none; }
  .exam-bar { padding-top: env(safe-area-inset-top); background: var(--sheet); border-bottom: 1px solid var(--rule); }
  .exam-bar .wrap { flex-wrap: nowrap; padding: 8px 0; gap: 8px; }
  .exit-link { display: grid; place-items: center; width: 40px; height: 40px; border-radius: 50%; color: var(--ink); flex: none; }
  .exit-link svg { width: 22px; height: 22px; }
  .exit-link:active { background: var(--desk); }
  .bar-status { flex: 1; text-align: center; }
  .bar-status .answered { display: none; }
  .timer { font-size: 1.15rem; }
  .bar-actions .btn { min-height: 38px; padding: 6px 14px; font-size: 0.9rem; border-radius: 999px; }

  .paged .exam-cover, .paged .results, .paged .paper .q, .paged .end-paper { display: none; }
  .paged .paper { display: none; }
  .paged.on-question .paper { display: block; }
  .paged .exam-cover.current, .paged .results.current { display: block; }
  .paged .paper .q.current { display: grid; border-bottom: 0; }
  .paged .exam-cover, .paged .results { margin: 12px 0; }
  .exam-cover { padding: 20px; }
  .exam-cover h1 { font-size: 1.55rem; }
  .paper { padding: 4px 18px 10px; margin-top: 12px; }
  .paged .q { padding-top: 18px; }
  .q { grid-template-columns: 1fr; }
  .q-num { font-size: 0.85rem !important; color: var(--ink-soft); font-weight: 600; }
  .paged .q-num::before { content: "Question "; }
  .q-body { font-size: 1.12rem; }
  .q-topic { margin: 2px 0 10px; }
  .answer-row { justify-content: flex-start; background: var(--desk); border-radius: 12px; padding: 6px 12px; }
  .answer-input { flex: 1; min-width: 0; width: auto; font-size: 1.2rem; text-align: left; border-bottom: 0; padding: 12px 2px; }
  .answer-input:focus { border-bottom: 0; background: transparent; }
  .answer-row:focus-within { outline: 2px solid var(--ink); }
  .choices { justify-content: flex-start; width: 100%; padding: 4px 0; }
  .choice { flex: 1; }
  .choice span { display: block; min-height: 48px; line-height: 30px; border-radius: 10px; background: var(--sheet); }
  .marks-tag { min-width: 0; font-size: 0.85rem; }
  .verdict { border-radius: 12px; border-left-width: 4px; }
  .figure { max-width: 100%; }

  .results { padding: 20px; }
  .score-line { gap: 6px 16px; }
  .topic-table th:nth-child(2), .topic-table td:nth-child(2) { width: 30%; }

  /* Bottom pager */
  .pager {
    display: grid; grid-template-columns: auto 1fr auto; gap: 8px; align-items: center;
    position: fixed; left: 0; right: 0; bottom: 0; z-index: 30;
    padding: 10px 12px calc(10px + env(safe-area-inset-bottom));
    background: var(--sheet); border-top: 1px solid var(--rule);
  }
  .pager-btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 4px;
    min-width: 48px; height: 48px; padding: 0 14px; border-radius: 14px;
    border: 0; background: var(--desk); color: var(--ink); font: 700 0.95rem var(--ui-font); cursor: pointer;
  }
  .pager-btn svg { width: 20px; height: 20px; }
  .pager-btn.next { background: var(--ink); color: var(--sheet); padding: 0 12px 0 18px; }
  .pager-btn.finish { background: var(--pen); }
  .pager-btn:disabled { opacity: 0.35; }
  .pager-btn:active:not(:disabled) { transform: scale(0.96); }
  .pager-mid { display: flex; flex-direction: column; gap: 6px; align-items: stretch; background: none; border: 0; padding: 4px; color: var(--ink); font: 600 0.85rem var(--ui-font); cursor: pointer; }
  .pager-track { height: 5px; border-radius: 3px; background: var(--rule); overflow: hidden; }
  .pager-track span { display: block; height: 100%; width: 0; background: var(--pen); transition: width 0.2s; }

  /* Question navigator: bottom sheet */
  .qnav[open] {
    display: block; position: fixed; inset: auto 0 0 0; margin: 0; width: 100%; max-width: none; max-height: 75vh;
    border: 0; border-radius: 20px 20px 0 0; padding: 8px 16px calc(18px + env(safe-area-inset-bottom));
    background: var(--sheet); color: var(--ink); overflow-y: auto;
    animation: sheet-up 0.22s ease-out;
  }
  .qnav::backdrop { background: rgba(10, 16, 30, 0.45); }
  .qnav-head { display: flex; justify-content: space-between; align-items: center; padding: 6px 0 10px; }
  .qnav-head::before { content: ""; position: absolute; top: 8px; left: 50%; width: 38px; height: 4px; margin-left: -19px; border-radius: 2px; background: var(--rule); }
  .qnav-head h2 { margin: 10px 0 0; font-size: 1.1rem; }
  .qnav-close { width: 40px; height: 40px; border: 0; border-radius: 50%; background: var(--desk); color: var(--ink); display: grid; place-items: center; }
  .qnav-close svg { width: 18px; height: 18px; }
  .qnav-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 8px; }
  .qnav-grid button { aspect-ratio: 1; border-radius: 12px; border: 1.5px solid var(--rule); background: var(--sheet); color: var(--ink); font: 700 0.95rem var(--paper-font); }
  .qnav-grid button.is-current { outline: 3px solid var(--pen); outline-offset: 2px; }
  .qnav-grid button.answered { background: var(--ink); border-color: var(--ink); color: var(--sheet); }
  .qnav-grid button.right { background: var(--ok); border-color: var(--ok); color: #fff; }
  .qnav-grid button.wrong { background: var(--pen); border-color: var(--pen); color: #fff; }
  .qnav-key { display: flex; align-items: center; gap: 6px; margin: 14px 0 0; }
  .dot { display: inline-block; width: 12px; height: 12px; border-radius: 4px; border: 1.5px solid var(--rule); }
  .dot.answered { background: var(--ink); border-color: var(--ink); margin-right: 0; }
  .qnav-key .dot + .dot, .qnav-key span:nth-child(2) { margin-left: 10px; }
}

@keyframes sheet-up { from { transform: translateY(40px); opacity: 0; } to { transform: none; opacity: 1; } }
@media (prefers-reduced-motion: reduce) { .qnav[open] { animation: none; } }

/* Installed app (home screen): no browser chrome, so keep it tidy */
@media (display-mode: standalone) {
  .site-footer { display: none; }
}