/* OpenTests – czarno-biały interfejs z jednym akcentem zieleni dla poprawnych i czerwieni dla błędnych odpowiedzi. */

:root {
  --scale: 1;
  --bg: #ffffff;
  --bg-soft: #f5f5f4;
  --card: #ffffff;
  --card-2: #fafaf9;
  --fg: #0a0a0a;
  --fg-2: #3f3f46;
  --muted: #71717a;
  --line: #e4e4e7;
  --line-2: #d4d4d8;
  --accent: #0a0a0a;
  --on-accent: #ffffff;
  --ok: #15803d;
  --ok-bg: #dcfce7;
  --bad: #b91c1c;
  --bad-bg: #fee2e2;
  --warn: #a16207;
  --warn-bg: #fef3c7;
  --focus: #2563eb;
  --shadow: 0 1px 2px rgba(0, 0, 0, .04), 0 8px 24px rgba(0, 0, 0, .06);
  --radius: 16px;
  --radius-sm: 10px;
  --font: 'Inter', 'Segoe UI', system-ui, -apple-system, Roboto, 'Helvetica Neue', Arial, sans-serif;
  --serif: 'Iowan Old Style', 'Palatino Linotype', Palatino, 'Book Antiqua', Georgia, serif;
  --mono: 'JetBrains Mono', 'Cascadia Mono', Consolas, 'SF Mono', Menlo, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #000000;
    --bg-soft: #0b0b0c;
    --card: #0e0e10;
    --card-2: #141417;
    --fg: #fafafa;
    --fg-2: #d4d4d8;
    --muted: #8e8e96;
    --line: #232327;
    --line-2: #34343a;
    --accent: #fafafa;
    --on-accent: #000000;
    --ok: #4ade80;
    --ok-bg: rgba(74, 222, 128, .12);
    --bad: #f87171;
    --bad-bg: rgba(248, 113, 113, .12);
    --warn: #fbbf24;
    --warn-bg: rgba(251, 191, 36, .12);
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 12px 32px rgba(0, 0, 0, .45);
    color-scheme: dark;
  }
}

:root[data-theme='dark'] {
  --bg: #000000;
  --bg-soft: #0b0b0c;
  --card: #0e0e10;
  --card-2: #141417;
  --fg: #fafafa;
  --fg-2: #d4d4d8;
  --muted: #8e8e96;
  --line: #232327;
  --line-2: #34343a;
  --accent: #fafafa;
  --on-accent: #000000;
  --ok: #4ade80;
  --ok-bg: rgba(74, 222, 128, .12);
  --bad: #f87171;
  --bad-bg: rgba(248, 113, 113, .12);
  --warn: #fbbf24;
  --warn-bg: rgba(251, 191, 36, .12);
  --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 12px 32px rgba(0, 0, 0, .45);
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; font-size: calc(16px * var(--scale)); scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--fg);
  font: 400 1rem/1.55 var(--font);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

main { flex: 1; outline: none; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; }
button, input, select, textarea { font: inherit; color: inherit; }
::selection { background: var(--accent); color: var(--on-accent); }
:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; border-radius: 6px; }

.wrap { width: 100%; max-width: 1180px; margin: 0 auto; padding: 0 20px; }
.wrap.narrow { max-width: 860px; }
.skip { position: absolute; left: -9999px; top: 8px; background: var(--accent); color: var(--on-accent); padding: 8px 14px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 12px; }

h1, h2, h3, h4 { margin: 0; line-height: 1.15; letter-spacing: -.02em; font-weight: 700; }
h1 { font-size: clamp(2rem, 4.5vw, 3.1rem); letter-spacing: -.035em; }
h2 { font-size: clamp(1.45rem, 2.6vw, 2rem); }
h3 { font-size: 1.15rem; }
p { margin: 0; }
.muted { color: var(--muted); }
.mono { font-family: var(--mono); font-feature-settings: 'zero' 1; }
.small { font-size: .875rem; }
.tiny { font-size: .78rem; }
.center { text-align: center; }
.hidden { display: none !important; }
@media (max-width: 600px) { .hide-sm { display: none; } }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ------------------------------------------------------------------ Topbar */

.topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(1.6) blur(14px);
  -webkit-backdrop-filter: saturate(1.6) blur(14px);
  border-bottom: 1px solid var(--line);
}
.topbar-inner { display: flex; align-items: center; gap: 14px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 750; font-size: 1.12rem; letter-spacing: -.02em; }
.brand-mark { width: 30px; height: 30px; color: var(--fg); }
.nav { display: flex; gap: 2px; margin-left: auto; }
.nav a { text-decoration: none; padding: 8px 12px; border-radius: 999px; color: var(--fg-2); font-weight: 520; font-size: .95rem; }
.nav a:hover { background: var(--bg-soft); color: var(--fg); }
.nav a.active { background: var(--accent); color: var(--on-accent); }
.icon-btn { width: 40px; height: 40px; display: grid; place-items: center; border-radius: 999px; border: 1px solid var(--line); background: var(--card); cursor: pointer; flex: none; }
.icon-btn svg { width: 19px; height: 19px; }
.icon-btn:hover { border-color: var(--line-2); background: var(--bg-soft); }
.menu-btn { display: none; }

@media (max-width: 820px) {
  .menu-btn { display: grid; }
  .theme-toggle { margin-left: auto; }
  .nav {
    position: fixed;
    inset: 64px 0 auto 0;
    flex-direction: column;
    gap: 4px;
    padding: 12px 16px 18px;
    background: var(--bg);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: opacity .18s ease, transform .18s ease;
  }
  .nav.open { opacity: 1; transform: none; pointer-events: auto; }
  .nav a { padding: 12px 14px; border-radius: 12px; font-size: 1rem; }
}

/* ------------------------------------------------------------------ Footer */

.footer { border-top: 1px solid var(--line); margin-top: 72px; padding: 28px 0 calc(28px + env(safe-area-inset-bottom)); font-size: .9rem; }
.footer-inner { display: grid; gap: 8px; grid-template-columns: 1fr auto; align-items: center; }
.footer-brand { display: flex; flex-direction: column; gap: 2px; }
.footer-brand span { color: var(--muted); }
.credit { text-align: right; }
.credit a { text-decoration: none; font-weight: 600; }
.credit a:hover { text-decoration: underline; }
.credit .dot { color: var(--muted); margin: 0 6px; }
.coffee { white-space: nowrap; }
.version { grid-column: 1 / -1; color: var(--muted); font-family: var(--mono); font-size: .75rem; }
@media (max-width: 700px) {
  .footer-inner { grid-template-columns: 1fr; }
  .credit { text-align: left; }
}

/* ------------------------------------------------------------------ Buttons & inputs */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 18px;
  border-radius: 999px;
  border: 1px solid var(--line-2);
  background: var(--card);
  color: var(--fg);
  font-weight: 600;
  font-size: .95rem;
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
  transition: transform .08s ease, background .15s ease, border-color .15s ease;
  user-select: none;
}
.btn:hover { border-color: var(--fg); }
.btn:active { transform: scale(.98); }
.btn.primary { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }
.btn.primary:hover { opacity: .9; }
.btn.ghost { background: transparent; border-color: transparent; }
.btn.ghost:hover { background: var(--bg-soft); }
.btn.danger { color: var(--bad); }
.btn.danger:hover { border-color: var(--bad); }
.btn.lg { min-height: 52px; padding: 0 26px; font-size: 1.02rem; }
.btn.sm { min-height: 34px; padding: 0 12px; font-size: .85rem; }
.btn[disabled] { opacity: .45; pointer-events: none; }
.btn svg { width: 18px; height: 18px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }

.field { display: grid; gap: 6px; }
.field > label, .label { font-size: .82rem; font-weight: 650; color: var(--fg-2); letter-spacing: .01em; }
.hint { font-size: .8rem; color: var(--muted); }
.input, select.input, textarea.input {
  width: 100%;
  min-height: 44px;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--line-2);
  background: var(--card);
  outline: none;
  transition: border-color .15s ease, box-shadow .15s ease;
}
.input:focus { border-color: var(--fg); box-shadow: 0 0 0 3px color-mix(in srgb, var(--fg) 12%, transparent); }
select.input { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 20px) 52%, calc(100% - 15px) 52%; background-size: 5px 5px; background-repeat: no-repeat; padding-right: 38px; }
input[type='range'] { width: 100%; accent-color: var(--fg); }

.seg { display: flex; padding: 4px; gap: 4px; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 999px; }
.seg button { flex: 1; min-height: 36px; border: 0; background: transparent; border-radius: 999px; cursor: pointer; font-weight: 600; font-size: .88rem; color: var(--fg-2); padding: 0 10px; }
.seg button.on { background: var(--accent); color: var(--on-accent); }

.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 36px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--line-2);
  background: var(--card);
  cursor: pointer;
  font-size: .88rem;
  font-weight: 560;
}
.chip.on { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }
.chip .count { font-family: var(--mono); font-size: .75rem; opacity: .7; }

.switch { display: flex; align-items: center; justify-content: space-between; gap: 14px; cursor: pointer; padding: 6px 0; }
.switch input { position: absolute; opacity: 0; pointer-events: none; }
.switch .track { width: 44px; height: 26px; border-radius: 999px; background: var(--line-2); position: relative; flex: none; transition: background .15s ease; }
.switch .track::after { content: ''; position: absolute; top: 3px; left: 3px; width: 20px; height: 20px; border-radius: 50%; background: var(--card); box-shadow: 0 1px 3px rgba(0, 0, 0, .25); transition: transform .15s ease; }
.switch input:checked + .track { background: var(--accent); }
.switch input:checked + .track::after { transform: translateX(18px); background: var(--on-accent); }
.switch input:focus-visible + .track { outline: 2px solid var(--focus); outline-offset: 2px; }
.switch-text { display: grid; gap: 1px; }
.switch-text small { color: var(--muted); font-size: .8rem; }

/* ------------------------------------------------------------------ Cards */

.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; }
.card.soft { background: var(--card-2); }
.card-title { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 14px; }
.card-title h3 { font-size: 1.02rem; }
.stack { display: grid; gap: 16px; }
.stack.sm { gap: 10px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 960px) { .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 600px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; } }

.page-head { padding: 40px 0 26px; display: flex; flex-wrap: wrap; gap: 16px; align-items: flex-end; justify-content: space-between; }
.page-head p { color: var(--muted); margin-top: 8px; max-width: 640px; }
.eyebrow { font-family: var(--mono); font-size: .74rem; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); margin-bottom: 10px; display: block; }

.badge { display: inline-flex; align-items: center; gap: 5px; padding: 2px 9px; border-radius: 999px; font-size: .74rem; font-weight: 650; border: 1px solid var(--line-2); color: var(--fg-2); white-space: nowrap; }
.badge.ok { color: var(--ok); background: var(--ok-bg); border-color: transparent; }
.badge.bad { color: var(--bad); background: var(--bad-bg); border-color: transparent; }
.badge.warn { color: var(--warn); background: var(--warn-bg); border-color: transparent; }
.badge.solid { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }

.empty { text-align: center; padding: 56px 20px; color: var(--muted); }
.empty h3 { color: var(--fg); margin-bottom: 8px; }
.empty .btn-row { justify-content: center; margin-top: 18px; }

/* ------------------------------------------------------------------ Boot */

.boot { min-height: 50vh; display: grid; place-content: center; justify-items: center; gap: 14px; color: var(--muted); }
.spinner { width: 28px; height: 28px; border-radius: 50%; border: 3px solid var(--line-2); border-top-color: var(--fg); animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ------------------------------------------------------------------ Home */

.hero { padding: 64px 0 40px; display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr); gap: 48px; align-items: center; }
.hero h1 { font-size: clamp(2.4rem, 6vw, 4.4rem); line-height: 1.02; }
.hero h1 em { font-family: var(--serif); font-style: italic; font-weight: 500; letter-spacing: -.01em; }
.hero .lead { font-size: 1.15rem; color: var(--fg-2); margin: 20px 0 28px; max-width: 560px; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 26px; margin-top: 34px; }
.hero-stats div { display: grid; }
.hero-stats strong { font-size: 1.7rem; letter-spacing: -.03em; font-family: var(--mono); font-weight: 600; }
.hero-stats span { color: var(--muted); font-size: .85rem; }
@media (max-width: 900px) { .hero { grid-template-columns: 1fr; gap: 32px; padding-top: 40px; } }

.demo { position: relative; }
.demo-card { background: var(--card); border: 1px solid var(--line); border-radius: 22px; padding: 22px; box-shadow: var(--shadow); }
.demo-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 14px; }
.demo-q { font-size: 1.08rem; min-height: 3.2em; }
.demo-foot { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-top: 14px; }
.demo-stack { position: absolute; inset: 14px -10px -12px 14px; border: 1px solid var(--line); border-radius: 22px; background: var(--card-2); z-index: -1; }

.section { padding: 56px 0 10px; }
.section-head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: flex-end; gap: 16px; margin-bottom: 26px; }
.section-head p { color: var(--muted); max-width: 560px; margin-top: 8px; }

.subject-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
@media (max-width: 960px) { .subject-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 600px) { .subject-grid { grid-template-columns: 1fr; } }
.subject-card { display: grid; grid-template-columns: auto 1fr; gap: 6px 16px; padding: 20px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); text-decoration: none; transition: border-color .15s ease, transform .15s ease; }
.subject-card:hover { border-color: var(--fg); transform: translateY(-2px); }
.subject-icon { grid-row: span 3; width: 48px; height: 48px; border-radius: 14px; display: grid; place-items: center; background: var(--accent); color: var(--on-accent); font-weight: 700; font-size: 1.25rem; font-family: var(--serif); }
.subject-card p { color: var(--muted); font-size: .9rem; }
.subject-card .meta { font-family: var(--mono); font-size: .75rem; color: var(--muted); }

.feature-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
@media (max-width: 960px) { .feature-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 560px) { .feature-grid { grid-template-columns: 1fr; } }
.feature { background: var(--card); padding: 22px; display: grid; gap: 8px; align-content: start; }
.feature-ico { width: 36px; height: 36px; border-radius: 10px; border: 1px solid var(--line-2); display: grid; place-items: center; }
.feature-ico svg { width: 19px; height: 19px; }
.feature p { color: var(--muted); font-size: .9rem; }

.steps { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; counter-reset: step; }
@media (max-width: 760px) { .steps { grid-template-columns: 1fr; } }
.step { padding: 22px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); }
.step::before { counter-increment: step; content: '0' counter(step); display: block; font-family: var(--mono); color: var(--muted); font-size: .8rem; margin-bottom: 14px; }
.step p { color: var(--muted); margin-top: 6px; font-size: .92rem; }

.preset-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; }
@media (max-width: 960px) { .preset-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 520px) { .preset-grid { grid-template-columns: 1fr; } }
.preset { text-align: left; padding: 18px; border-radius: var(--radius); border: 1px solid var(--line); background: var(--card); cursor: pointer; display: grid; gap: 6px; transition: border-color .15s ease; }
.preset:hover { border-color: var(--fg); }
.preset strong { font-size: .98rem; }
.preset span { color: var(--muted); font-size: .84rem; }
.preset .meta { font-family: var(--mono); font-size: .74rem; }

.support { margin-top: 56px; padding: 30px; border-radius: 22px; background: var(--accent); color: var(--on-accent); display: flex; flex-wrap: wrap; gap: 20px; align-items: center; justify-content: space-between; }
.support p { opacity: .75; margin-top: 6px; max-width: 560px; }
.support .btn { background: var(--on-accent); color: var(--accent); border-color: var(--on-accent); }

/* ------------------------------------------------------------------ Creator */

.creator { display: grid; grid-template-columns: minmax(0, 1fr) 380px; gap: 22px; align-items: start; }
@media (max-width: 980px) { .creator { grid-template-columns: 1fr; } }
.creator-side { position: sticky; top: 84px; display: grid; gap: 16px; }
@media (max-width: 980px) { .creator-side { position: static; } }

.toolbar { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-bottom: 14px; }
.search { position: relative; flex: 1; min-width: 200px; }
.search svg { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); width: 17px; height: 17px; color: var(--muted); }
.search .input { padding-left: 40px; border-radius: 999px; }

.subject-block { border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); margin-bottom: 12px; overflow: hidden; }
.subject-head { display: flex; align-items: center; gap: 14px; padding: 14px 16px; cursor: pointer; user-select: none; }
.subject-head .subject-icon { width: 38px; height: 38px; border-radius: 11px; font-size: 1.05rem; grid-row: auto; }
.subject-head h3 { font-size: 1rem; }
.subject-head .meta { font-family: var(--mono); font-size: .74rem; color: var(--muted); }
.subject-head .grow { flex: 1; min-width: 0; }
.subject-head .chev { width: 18px; height: 18px; transition: transform .2s ease; color: var(--muted); flex: none; }
.subject-block.open .chev { transform: rotate(180deg); }
.subject-body { display: none; padding: 4px 10px 12px; border-top: 1px solid var(--line); }
.subject-block.open .subject-body { display: block; }
.subject-actions { display: flex; gap: 8px; padding: 10px 6px 6px; flex-wrap: wrap; }
.topic-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr)); gap: 2px 8px; }
@media (max-width: 640px) { .topic-list { grid-template-columns: 1fr; } }
.topic { display: flex; align-items: center; gap: 10px; padding: 9px 8px; border-radius: 10px; cursor: pointer; }
.topic:hover { background: var(--bg-soft); }
.topic input { width: 18px; height: 18px; accent-color: var(--fg); flex: none; margin: 0; }
.topic .t-name { flex: 1; min-width: 0; font-size: .92rem; }
.topic .t-name small { display: block; color: var(--muted); font-size: .76rem; line-height: 1.3; }
.topic .lv { font-family: var(--mono); font-size: .68rem; color: var(--muted); white-space: nowrap; }
.topic .peek { border: 0; background: none; padding: 4px; cursor: pointer; color: var(--muted); border-radius: 6px; flex: none; }
.topic .peek:hover { color: var(--fg); background: var(--line); }
.topic .peek svg { width: 17px; height: 17px; }
.topic.dim .t-name { color: var(--muted); }
.check-all { width: 18px; height: 18px; accent-color: var(--fg); }

.summary { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border-radius: 12px; overflow: hidden; border: 1px solid var(--line); }
.summary div { background: var(--card-2); padding: 10px 12px; display: grid; }
.summary strong { font-family: var(--mono); font-size: 1.15rem; font-weight: 600; }
.summary span { font-size: .74rem; color: var(--muted); }
.seed-row { display: flex; gap: 8px; }
.seed-row .input { font-family: var(--mono); text-transform: uppercase; letter-spacing: .08em; }

.template-list { display: grid; gap: 8px; }
.template { display: flex; align-items: center; gap: 10px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 12px; }
.template .grow { flex: 1; min-width: 0; }
.template strong { display: block; font-size: .92rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.template span { font-size: .78rem; color: var(--muted); }

/* ------------------------------------------------------------------ Test */

.test-bar { position: sticky; top: 64px; z-index: 30; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); border-bottom: 1px solid var(--line); }
.test-bar-inner { display: flex; align-items: center; gap: 14px; min-height: 58px; padding-top: 8px; padding-bottom: 8px; }
.test-title { min-width: 0; flex: 1; }
.test-title strong { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.test-title span { font-size: .8rem; color: var(--muted); }
.timer { font-family: var(--mono); font-size: 1.05rem; font-weight: 600; padding: 6px 12px; border-radius: 999px; border: 1px solid var(--line-2); white-space: nowrap; }
.timer.low { color: var(--bad); border-color: var(--bad); animation: pulse 1s ease-in-out infinite; }
@keyframes pulse { 50% { opacity: .55; } }
.progress { height: 3px; background: var(--line); }
.progress > div { height: 100%; background: var(--fg); transition: width .25s ease; }

.test-layout { display: grid; grid-template-columns: minmax(0, 1fr) 270px; gap: 22px; padding-top: 24px; align-items: start; }
@media (max-width: 900px) { .test-layout { grid-template-columns: 1fr; } }
.navigator { position: sticky; top: 150px; }
@media (max-width: 900px) { .navigator { position: static; order: -1; } .navigator .card { padding: 14px; } }
.nav-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(38px, 1fr)); gap: 6px; }
.nav-grid button { aspect-ratio: 1; border-radius: 10px; border: 1px solid var(--line-2); background: var(--card); cursor: pointer; font-family: var(--mono); font-size: .82rem; font-weight: 600; position: relative; }
.nav-grid button.answered { background: var(--fg-2); color: var(--bg); border-color: var(--fg-2); }
.nav-grid button.current { outline: 2px solid var(--fg); outline-offset: 2px; }
.nav-grid button.flagged::after { content: ''; position: absolute; top: 3px; right: 3px; width: 7px; height: 7px; border-radius: 50%; background: var(--warn); }
.nav-grid button.ok { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.nav-grid button.bad { background: var(--bad-bg); color: var(--bad); border-color: transparent; }
.legend { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 12px; font-size: .76rem; color: var(--muted); }
.legend i { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 5px; vertical-align: -1px; border: 1px solid var(--line-2); }
.legend i.a { background: var(--fg-2); border-color: var(--fg-2); }
.legend i.f { background: var(--warn); border-color: var(--warn); border-radius: 50%; }

.question { background: var(--card); border: 1px solid var(--line); border-radius: 20px; padding: 26px; scroll-margin-top: 140px; }
.question + .question { margin-top: 16px; }
.q-head { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-bottom: 14px; }
.q-num { font-family: var(--mono); font-weight: 700; font-size: .85rem; padding: 3px 10px; border-radius: 999px; background: var(--accent); color: var(--on-accent); }
.q-topic { font-size: .8rem; color: var(--muted); }
.q-points { margin-left: auto; font-family: var(--mono); font-size: .76rem; color: var(--muted); }
.q-prompt { font-size: 1.12rem; line-height: 1.6; }
.q-type { font-size: .78rem; color: var(--muted); margin-top: 10px; }
.q-claim { margin-top: 14px; padding: 14px 16px; border-radius: 14px; background: var(--bg-soft); border: 1px solid var(--line); font-size: 1.05rem; }
.q-claim small { display: block; color: var(--muted); font-size: .8rem; margin-bottom: 4px; }

.options { display: grid; gap: 10px; margin-top: 18px; }
.option { display: flex; align-items: center; gap: 14px; padding: 13px 16px; border-radius: 14px; border: 1px solid var(--line-2); background: var(--card); cursor: pointer; text-align: left; width: 100%; transition: border-color .12s ease, background .12s ease; font-size: 1rem; }
.option:hover { border-color: var(--fg); }
.option .key { flex: none; width: 30px; height: 30px; border-radius: 9px; display: grid; place-items: center; font-family: var(--mono); font-weight: 700; font-size: .85rem; border: 1px solid var(--line-2); }
.option.multi .key { border-radius: 7px; }
.option.on { border-color: var(--fg); background: var(--bg-soft); box-shadow: inset 0 0 0 1px var(--fg); }
.option.on .key { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }
.option.correct { border-color: var(--ok); background: var(--ok-bg); box-shadow: none; }
.option.correct .key { background: var(--ok); color: var(--bg); border-color: var(--ok); }
.option.wrong { border-color: var(--bad); background: var(--bad-bg); box-shadow: none; }
.option.wrong .key { background: var(--bad); color: var(--bg); border-color: var(--bad); }
.option[disabled] { cursor: default; }
.option .txt { flex: 1; min-width: 0; overflow-wrap: anywhere; }
.tf { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 18px; }
.tf .option { justify-content: center; font-weight: 650; }

.open-answer { display: flex; gap: 10px; align-items: center; margin-top: 18px; }
.open-answer .input { font-size: 1.1rem; min-height: 52px; font-family: var(--mono); max-width: 360px; }
.open-answer .unit { color: var(--muted); font-weight: 600; }
.open-answer.ok .input { border-color: var(--ok); background: var(--ok-bg); }
.open-answer.bad .input { border-color: var(--bad); background: var(--bad-bg); }
.input-help { font-size: .78rem; color: var(--muted); margin-top: 8px; }

.q-actions { display: flex; flex-wrap: wrap; gap: 10px; justify-content: space-between; margin-top: 22px; }
.q-actions .btn-row:last-child { margin-left: auto; }
.flag-btn.on { color: var(--warn); border-color: var(--warn); }

.explain { margin-top: 16px; padding: 14px 16px; border-radius: 14px; background: var(--card-2); border: 1px dashed var(--line-2); font-size: .95rem; }
.explain strong.title { display: block; font-size: .78rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin-bottom: 6px; }
.verdict { display: flex; align-items: center; gap: 10px; margin-top: 16px; font-weight: 650; }
.verdict.ok { color: var(--ok); }
.verdict.bad { color: var(--bad); }

/* Maths and science markup */
.expr { font-family: var(--serif); font-size: 1.12em; white-space: nowrap; padding: 0 2px; }
.frac { display: inline-flex; flex-direction: column; align-items: center; vertical-align: middle; font-size: .9em; margin: 0 2px; line-height: 1.1; }
.frac > span:first-child { border-bottom: 1.5px solid currentColor; padding: 0 3px 1px; }
.frac > span:last-child { padding: 1px 3px 0; }
.sqrt { white-space: nowrap; }
.sqrt > span { border-top: 1.5px solid currentColor; padding: 0 2px; margin-left: 1px; }
.sqrt-in { border-top: 1.5px solid currentColor; padding: 0 2px; }
sup, sub { font-size: .72em; line-height: 0; }
.nuclide { display: inline-flex; flex-direction: column; font-size: .7em; line-height: 1.05; vertical-align: middle; text-align: right; margin-right: 1px; }
.nuclide sup, .nuclide sub { font-size: 1em; line-height: 1.05; vertical-align: baseline; }
.system { display: inline-flex; flex-direction: column; gap: 2px; padding: 4px 0 4px 14px; margin: 6px 0; position: relative; font-family: var(--serif); vertical-align: middle; }
.system::before { content: '{'; position: absolute; left: 0; top: 50%; transform: translateY(-50%) scaleY(1.9); font-size: 1.4em; font-family: var(--font); font-weight: 300; }
.matrix { display: inline-grid; gap: 2px; padding: 6px 12px; margin: 6px 4px; vertical-align: middle; font-family: var(--mono); border: 1.5px solid currentColor; border-radius: 10px; }
.matrix > span { display: flex; gap: 14px; justify-content: flex-end; }
.matrix i { font-style: normal; min-width: 1.6em; text-align: right; }
.eq { font-family: var(--serif); white-space: normal; padding: 0 2px; }
.note { display: inline-block; color: var(--muted); font-size: .9em; }
.code { font-family: var(--mono); font-size: .88rem; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; margin: 12px 0; overflow-x: auto; line-height: 1.55; white-space: pre; }
.table-inline { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0; }
.table-inline span { font-family: var(--mono); font-size: .82rem; padding: 4px 8px; border-radius: 8px; border: 1px solid var(--line); }
.table-inline b { color: var(--muted); font-weight: 600; margin-right: 4px; }

/* ------------------------------------------------------------------ Result */

.result-hero { display: grid; grid-template-columns: auto 1fr; gap: 34px; align-items: center; padding: 34px 0 10px; }
@media (max-width: 700px) { .result-hero { grid-template-columns: 1fr; justify-items: center; text-align: center; } }
.ring { width: 190px; height: 190px; position: relative; }
.ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.ring .val { position: absolute; inset: 0; display: grid; place-content: center; text-align: center; }
.ring .val strong { font-size: 2.6rem; font-family: var(--mono); letter-spacing: -.04em; }
.ring .val span { color: var(--muted); font-size: .85rem; }
.grade-big { font-size: clamp(2rem, 5vw, 3rem); }
.stat-row { display: flex; flex-wrap: wrap; gap: 26px; margin-top: 18px; }
@media (max-width: 700px) { .stat-row { justify-content: center; } }
.stat-row div { display: grid; }
.stat-row strong { font-family: var(--mono); font-size: 1.3rem; }
.stat-row span { color: var(--muted); font-size: .8rem; }

.bars { display: grid; gap: 12px; }
.bar-row { display: grid; grid-template-columns: minmax(120px, 240px) 1fr auto; gap: 14px; align-items: center; font-size: .9rem; }
@media (max-width: 600px) { .bar-row { grid-template-columns: 1fr auto; } .bar-row .bar { grid-column: 1 / -1; grid-row: 2; } }
.bar-row .name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.bar { height: 10px; border-radius: 999px; background: var(--line); overflow: hidden; }
.bar > div { height: 100%; border-radius: 999px; background: var(--fg); }
.bar.ok > div { background: var(--ok); }
.bar.mid > div { background: var(--warn); }
.bar.bad > div { background: var(--bad); }
.bar-row .pct { font-family: var(--mono); font-size: .82rem; color: var(--muted); min-width: 64px; text-align: right; }

.filter-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 20px 0 14px; }
.your-answer { margin-top: 14px; display: grid; gap: 6px; font-size: .95rem; }
.your-answer div { display: flex; gap: 10px; flex-wrap: wrap; }
.your-answer .k { color: var(--muted); min-width: 130px; }

/* ------------------------------------------------------------------ Practice */

.practice-stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; margin-bottom: 16px; }
@media (max-width: 600px) { .practice-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.practice-stats div { background: var(--card); padding: 14px 16px; display: grid; }
.practice-stats strong { font-family: var(--mono); font-size: 1.35rem; }
.practice-stats span { font-size: .76rem; color: var(--muted); }
.streak-fire { color: var(--warn); }

/* ------------------------------------------------------------------ History */

.tiles { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 12px; }
@media (max-width: 900px) { .tiles { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.tile { padding: 16px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); display: grid; gap: 2px; }
.tile strong { font-family: var(--mono); font-size: 1.5rem; font-weight: 600; letter-spacing: -.03em; }
.tile span { font-size: .78rem; color: var(--muted); }
.chart { width: 100%; height: 220px; }
.chart .grid line { stroke: var(--line); }
.chart .axis text { fill: var(--muted); font-size: 11px; font-family: var(--mono); }
.chart .line { fill: none; stroke: var(--fg); stroke-width: 2.2; stroke-linejoin: round; stroke-linecap: round; }
.chart .area { fill: var(--fg); opacity: .06; }
.chart .pt { fill: var(--bg); stroke: var(--fg); stroke-width: 2; }
.attempts { display: grid; gap: 8px; }
.attempt { display: grid; grid-template-columns: auto 1fr auto auto; gap: 14px; align-items: center; padding: 12px 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--card); }
@media (max-width: 640px) { .attempt { grid-template-columns: auto 1fr; } .attempt .btn-row { grid-column: 1 / -1; } }
.attempt .score { width: 54px; height: 54px; border-radius: 14px; display: grid; place-items: center; font-family: var(--mono); font-weight: 700; background: var(--bg-soft); border: 1px solid var(--line); }
.attempt .score.ok { color: var(--ok); background: var(--ok-bg); border-color: transparent; }
.attempt .score.mid { color: var(--warn); background: var(--warn-bg); border-color: transparent; }
.attempt .score.bad { color: var(--bad); background: var(--bad-bg); border-color: transparent; }
.attempt strong { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.attempt span { color: var(--muted); font-size: .8rem; }

/* ------------------------------------------------------------------ Tables (reference) */

.tabs { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 18px; }
.ptable-wrap { overflow-x: auto; padding-bottom: 6px; }
.ptable { display: grid; grid-template-columns: repeat(18, minmax(44px, 1fr)); gap: 3px; min-width: 860px; }
.el { aspect-ratio: 1 / 1.08; border-radius: 8px; border: 1px solid var(--line-2); background: var(--card); cursor: pointer; display: grid; grid-template-rows: auto 1fr auto; padding: 3px 4px; text-align: left; font-size: .62rem; line-height: 1.1; position: relative; }
.el:hover, .el.sel { border-color: var(--fg); box-shadow: inset 0 0 0 1px var(--fg); z-index: 1; }
.el b { font-size: 1.05rem; text-align: center; align-self: center; font-weight: 700; }
.el .z { font-family: var(--mono); color: var(--muted); }
.el .m { font-family: var(--mono); color: var(--muted); text-align: center; font-size: .56rem; overflow: hidden; white-space: nowrap; }
.el.gap { visibility: hidden; }
.el.c-am { background: color-mix(in srgb, #ef4444 14%, var(--card)); }
.el.c-ae { background: color-mix(in srgb, #f97316 14%, var(--card)); }
.el.c-tm { background: color-mix(in srgb, #eab308 12%, var(--card)); }
.el.c-pt { background: color-mix(in srgb, #22c55e 12%, var(--card)); }
.el.c-md { background: color-mix(in srgb, #14b8a6 14%, var(--card)); }
.el.c-nm { background: color-mix(in srgb, #3b82f6 13%, var(--card)); }
.el.c-hl { background: color-mix(in srgb, #8b5cf6 14%, var(--card)); }
.el.c-ng { background: color-mix(in srgb, #ec4899 13%, var(--card)); }
.el.c-ln { background: color-mix(in srgb, #a3a3a3 16%, var(--card)); }
.el.c-ac { background: color-mix(in srgb, #78716c 18%, var(--card)); }
.el.dim { opacity: .25; }
.cat-legend { display: flex; flex-wrap: wrap; gap: 6px; margin: 14px 0; }
.cat-legend button { border: 1px solid var(--line-2); border-radius: 999px; padding: 4px 10px; font-size: .78rem; cursor: pointer; background: var(--card); }
.cat-legend button i { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; }
.cat-legend button.on { border-color: var(--fg); box-shadow: inset 0 0 0 1px var(--fg); }
.el-detail { display: grid; grid-template-columns: 110px 1fr; gap: 20px; align-items: center; }
@media (max-width: 520px) { .el-detail { grid-template-columns: 1fr; } }
.el-big { width: 110px; height: 120px; border-radius: 16px; border: 2px solid var(--fg); display: grid; place-content: center; text-align: center; }
.el-big b { font-size: 2.4rem; line-height: 1; }
.el-big span { font-family: var(--mono); font-size: .8rem; color: var(--muted); }
.kv { display: grid; grid-template-columns: auto 1fr; gap: 6px 18px; font-size: .92rem; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; font-weight: 550; }
.formula-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 12px; }
.formula { padding: 16px; border: 1px solid var(--line); border-radius: 14px; background: var(--card); display: grid; gap: 8px; }
.formula h4 { font-size: .82rem; color: var(--muted); font-weight: 650; text-transform: uppercase; letter-spacing: .06em; }
.formula .f { font-family: var(--serif); font-size: 1.15rem; }
.formula p { font-size: .82rem; color: var(--muted); }
.data-table { width: 100%; border-collapse: collapse; font-size: .9rem; }
.data-table th, .data-table td { padding: 9px 12px; border-bottom: 1px solid var(--line); text-align: left; }
.data-table th { font-size: .76rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); font-weight: 650; }
.data-table td.mono { white-space: nowrap; }
.codon-table { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 8px; }
@media (max-width: 760px) { .codon-table { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.codon { font-family: var(--mono); font-size: .8rem; padding: 6px 8px; border-radius: 8px; border: 1px solid var(--line); display: flex; justify-content: space-between; gap: 6px; }
.codon.stop { color: var(--bad); }
.codon.start { color: var(--ok); }

/* ------------------------------------------------------------------ Modal & toast */

.modal-back { position: fixed; inset: 0; background: rgba(0, 0, 0, .55); z-index: 80; display: grid; place-items: center; padding: 20px; animation: fade .15s ease; }
.modal { width: min(640px, 100%); max-height: calc(100vh - 40px); overflow: auto; background: var(--card); border: 1px solid var(--line); border-radius: 22px; padding: 24px; box-shadow: var(--shadow); animation: rise .18s ease; }
.modal-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 14px; }
.modal-foot { display: flex; justify-content: flex-end; flex-wrap: wrap; gap: 10px; margin-top: 20px; }
@keyframes fade { from { opacity: 0; } }
@keyframes rise { from { transform: translateY(10px); opacity: 0; } }
.toast-host { position: fixed; left: 50%; bottom: calc(22px + env(safe-area-inset-bottom)); transform: translateX(-50%); z-index: 90; display: grid; gap: 8px; justify-items: center; pointer-events: none; }
.toast { background: var(--accent); color: var(--on-accent); padding: 11px 18px; border-radius: 999px; font-size: .9rem; font-weight: 600; box-shadow: var(--shadow); animation: rise .2s ease; max-width: calc(100vw - 32px); }

/* ------------------------------------------------------------------ Print sheet (screen preview) */

.print-controls { margin-bottom: 20px; }
.sheet-preview { background: var(--bg-soft); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; overflow-x: auto; }
.sheet { background: #fff; color: #000; width: 210mm; max-width: 100%; margin: 0 auto 22px; padding: 16mm 15mm; box-shadow: 0 2px 16px rgba(0, 0, 0, .12); font-size: calc(10.5pt * var(--print-scale, 1)); line-height: 1.45; }
.sheet h1 { font-size: 17pt; letter-spacing: -.01em; }
.sheet .sheet-head { display: flex; justify-content: space-between; gap: 16px; align-items: flex-start; padding-bottom: 10px; border-bottom: 2px solid #000; margin-bottom: 12px; }
.sheet .group { font-family: var(--mono); font-size: 14pt; font-weight: 700; border: 2px solid #000; border-radius: 8px; padding: 2px 10px; white-space: nowrap; }
.sheet .fields { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 14px; margin: 10px 0 14px; font-size: 9pt; }
.sheet .fields div { border-bottom: 1px solid #000; padding-top: 14px; }
.sheet .meta-line { font-size: 8.5pt; color: #444; display: flex; flex-wrap: wrap; gap: 4px 16px; }
.sheet .pq { break-inside: avoid; padding: 7px 0 9px; border-bottom: 1px solid #ddd; }
.sheet .pq-head { display: flex; gap: 8px; align-items: baseline; }
.sheet .pq-n { font-weight: 700; min-width: 22px; }
.sheet .pq-pts { margin-left: auto; font-size: 8pt; color: #555; white-space: nowrap; }
.sheet .pq-opts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 3px 18px; margin: 6px 0 0 30px; }
.sheet .pq-opts.one { grid-template-columns: 1fr; }
.sheet .pq-opts > span::before { content: attr(data-k); display: inline-grid; place-items: center; width: 16px; height: 16px; border: 1px solid #000; border-radius: 50%; font-size: 7.5pt; font-weight: 700; margin-right: 7px; vertical-align: 1px; }
.sheet .pq-opts.square > span::before { border-radius: 3px; }
.sheet .pq-line { margin: 10px 0 0 30px; border-bottom: 1px dotted #000; height: 18px; max-width: 70%; }
.sheet .pq-tf { margin: 6px 0 0 30px; display: flex; gap: 22px; font-weight: 600; }
.sheet .pq-tf > span::before { content: ''; display: inline-block; width: 12px; height: 12px; border: 1px solid #000; margin-right: 6px; vertical-align: -1px; }
.sheet .pq-claim { margin: 5px 0 0 30px; font-style: italic; }
.sheet .pq-body { flex: 1; }
.sheet .code, .sheet .table-inline span, .sheet .q-claim { background: #f6f6f6; border-color: #ccc; }
.sheet .key-table { width: 100%; border-collapse: collapse; font-size: 9pt; margin-top: 8px; }
.sheet .key-table th, .sheet .key-table td { border: 1px solid #999; padding: 4px 6px; text-align: left; vertical-align: top; }
.sheet .key-table th { background: #eee; }
.sheet .scale-table { border-collapse: collapse; font-size: 8pt; margin-top: 8px; }
.sheet .scale-table td { border: 1px solid #999; padding: 2px 6px; }
.sheet .sheet-foot { margin-top: 14px; font-size: 7.5pt; color: #666; display: flex; justify-content: space-between; }
.sheet.cols-2 .pq-list { columns: 2; column-gap: 9mm; }
.sheet .solution { font-size: 8.5pt; color: #333; margin: 3px 0 0 30px; }

@media print {
  @page { size: A4; margin: 0; }
  body { background: #fff; }
  .topbar, .footer, .no-print, .toast-host, .print-controls, .page-head { display: none !important; }
  .sheet-preview { background: none; border: 0; padding: 0; }
  .sheet { box-shadow: none; margin: 0; width: auto; break-after: page; }
  .sheet:last-child { break-after: auto; }
  main { padding: 0; }
  .wrap { max-width: none; padding: 0; }
}

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