:root {
  --bg: #f7f8f4;
  --panel: rgba(255,255,255,.86);
  --solid: #ffffff;
  --soft: #eef3ec;
  --text: #17201b;
  --muted: #68736b;
  --line: #dbe4d8;
  --brand: #276b5d;
  --brand-2: #55b09d;
  --brand-dark: #18473e;
  --accent: #a15a27;
  --ai: #6857c2;
  --good: #138a4b;
  --bad: #b42318;
  --warn: #a46412;
  --shadow: 0 18px 50px rgba(22,35,28,.10);
  --radius: 22px;
}
html[data-theme="dark"] {
  --bg: #0f1512;
  --panel: rgba(24,32,28,.86);
  --solid: #18201c;
  --soft: #202a25;
  --text: #eef5ef;
  --muted: #aab7ad;
  --line: #334038;
  --brand: #79c7b6;
  --brand-2: #a4dfd0;
  --brand-dark: #d6fff5;
  --accent: #e5a467;
  --ai: #c4b8ff;
  --good: #7dd99f;
  --bad: #ff9b92;
  --warn: #f2c879;
  --shadow: 0 18px 50px rgba(0,0,0,.34);
}
* { box-sizing: border-box; }
html { color-scheme: light; scroll-behavior: smooth; }
html[data-theme="dark"] { color-scheme: dark; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans HK", "Noto Sans TC", "Noto Sans CJK TC", Arial, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 7% 0%, color-mix(in srgb, var(--brand) 22%, transparent), transparent 24rem),
    radial-gradient(circle at 100% 4%, color-mix(in srgb, var(--ai) 13%, transparent), transparent 25rem),
    linear-gradient(180deg, color-mix(in srgb, var(--bg) 88%, white), var(--bg));
  min-height: 100vh;
}
button, input, textarea { font: inherit; }
button { cursor: pointer; }
button:disabled { cursor: wait; opacity: .68; }
a { color: inherit; text-decoration: none; }

.site-head {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: auto minmax(0,1fr) auto;
  align-items: center;
  gap: 12px;
  max-width: 1180px;
  margin: 0 auto;
  padding: 12px 16px;
  backdrop-filter: blur(18px);
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 70%, transparent);
}
.brand { display: inline-flex; align-items: center; gap: 10px; min-width: 220px; }
.brand-mark {
  width: 42px; height: 42px; border-radius: 15px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  color: var(--bg); font-weight: 950; box-shadow: 0 12px 26px color-mix(in srgb, var(--brand) 24%, transparent);
}
.brand b { display:block; font-size: 15px; }
.brand small { display:block; color: var(--muted); font-size: 12px; margin-top: 2px; }
.page-nav { display:flex; gap: 7px; justify-content:center; overflow-x:auto; padding: 3px; scrollbar-width: none; }
.page-nav::-webkit-scrollbar { display:none; }
.nav-pill {
  white-space: nowrap; padding: 10px 13px; border-radius: 999px; border:1px solid transparent;
  color: var(--muted); font-weight: 850; font-size: 14px; transition: .18s ease;
}
.nav-pill:hover { color: var(--text); background: var(--soft); transform: translateY(-1px); }
.nav-pill.active { color: var(--bg); background: var(--brand); box-shadow: 0 12px 24px color-mix(in srgb, var(--brand) 20%, transparent); }
.head-actions { display:flex; gap:8px; align-items:center; justify-content:flex-end; }
.icon-action, .icon-btn {
  border:1px solid var(--line); background: var(--solid); color: var(--text);
  border-radius: 13px; padding: 10px 12px; font-weight: 850; transition: .18s ease;
}
.icon-action:hover, .icon-btn:hover { transform: translateY(-1px); border-color: var(--brand); }
.icon-btn { width:42px; height:42px; font-size: 24px; display:grid; place-items:center; padding:0; }

.mobile-title, .stat-strip, .toolbar-row, .filter-panel, .page-main { max-width: 1180px; margin-left:auto; margin-right:auto; }
.mobile-title { padding: 20px 16px 10px; }
.mobile-title p { margin: 0 0 6px; color: var(--brand); font-size: 12px; font-weight: 950; letter-spacing:.08em; }
.mobile-title h1 { margin: 0; font-size: clamp(28px, 6vw, 48px); letter-spacing: -.03em; }
.stat-strip { display:grid; grid-template-columns: repeat(4,1fr); gap:10px; padding: 0 16px 12px; }
.stat-strip div {
  background: var(--panel); border:1px solid var(--line); border-radius:18px; padding:13px 14px;
  box-shadow: 0 10px 28px rgba(22,35,28,.05); animation: liftIn .36s ease both;
}
.stat-strip b { display:block; font-size: 22px; line-height:1; }
.stat-strip span { color:var(--muted); font-size:12px; display:block; margin-top:5px; }
.toolbar-row { display:flex; gap: 8px; padding: 0 16px 12px; }

.btn {
  position: relative;
  overflow: hidden;
  border: 0;
  border-radius: 15px;
  padding: 13px 16px;
  font-weight: 900;
  background: linear-gradient(135deg, var(--brand), var(--brand-dark));
  color: var(--bg);
  transition: transform .18s ease, box-shadow .18s ease, filter .18s ease;
  box-shadow: 0 12px 25px color-mix(in srgb, var(--brand) 20%, transparent);
}
.btn::after {
  content:""; position:absolute; inset:auto auto -35px -35px; width:80px; height:80px; border-radius:999px;
  background: rgba(255,255,255,.18); transition: transform .25s ease;
}
.btn:hover { transform: translateY(-2px); filter: saturate(1.04); }
.btn:hover::after { transform: translate(18px,-18px) scale(1.15); }
.btn.secondary { background: color-mix(in srgb, var(--brand) 14%, var(--solid)); color: var(--brand-dark); border:1px solid color-mix(in srgb, var(--brand) 28%, var(--line)); box-shadow:none; }
.btn.ghost { background: var(--solid); color: var(--text); border:1px solid var(--line); box-shadow:none; }
.btn.warn { background: color-mix(in srgb, var(--accent) 15%, var(--solid)); color: var(--accent); border:1px solid color-mix(in srgb, var(--accent) 35%, var(--line)); box-shadow:none; }
.btn.ai-btn { background: linear-gradient(135deg, var(--ai), color-mix(in srgb, var(--ai) 45%, var(--brand))); color:#fff; }
.btn.compact { padding: 10px 13px; border-radius: 13px; font-size: 14px; }
.btn.mini { padding: 9px 11px; border-radius: 12px; font-size: 13px; }

.filter-panel {
  display:none;
  grid-template-columns: minmax(220px,1.2fr) repeat(4, minmax(140px,.6fr)) auto;
  gap: 10px;
  align-items:end;
  padding: 0 16px 14px;
  animation: fadeSlide .24s ease both;
}
.filter-panel.open { display:grid; }
.search-wrap { position:relative; }
.search-icon { position:absolute; left:14px; top:50%; transform:translateY(-50%); color:var(--muted); font-weight:900; }
.control {
  width:100%; border:1px solid var(--line); background: var(--solid); color:var(--text);
  border-radius:16px; padding: 13px 14px; outline:none; transition:.18s ease;
}
.search-input { padding-left: 38px; }
.control:focus { border-color: var(--brand); box-shadow: 0 0 0 4px color-mix(in srgb, var(--brand) 16%, transparent); }
.custom-field > span { display:block; color:var(--muted); font-size:12px; font-weight:900; margin:0 0 6px 2px; }
.selectish { position: relative; }
.select-trigger {
  width:100%; min-height:46px; text-align:left; border:1px solid var(--line); border-radius:16px;
  background: var(--solid); color:var(--text); padding: 12px 38px 12px 14px; font-weight:850;
  box-shadow: inset 5px 5px 12px rgba(20,28,23,.04), inset -5px -5px 12px rgba(255,255,255,.34);
}
.select-trigger::after { content:"⌄"; position:absolute; right:14px; top:50%; transform:translateY(-50%); color:var(--muted); }
.select-menu {
  display:none; position:absolute; z-index: 35; top: calc(100% + 7px); left:0; right:0; max-height: 270px; overflow:auto;
  background: var(--solid); border:1px solid var(--line); border-radius:16px; padding:7px; box-shadow: var(--shadow);
  animation: pop .18s ease both;
}
.selectish.open .select-menu { display:block; }
.option-item {
  width:100%; text-align:left; border:0; background:transparent; color:var(--text); border-radius:12px; padding:10px 11px;
  font-weight:800; transition:.16s ease;
}
.option-item:hover, .option-item.active { background: color-mix(in srgb, var(--brand) 13%, var(--solid)); color: var(--brand-dark); }

.page-main { padding: 0 16px 82px; }
.home-grid { display:grid; grid-template-columns: 1.2fr .8fr; gap:14px; align-items:stretch; }
.hero-card, .glass-card, .quiz-card, .study-card, .stat-card {
  background: var(--panel); border:1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); backdrop-filter: blur(18px);
}
.hero-card { padding: clamp(22px, 4vw, 38px); position:relative; overflow:hidden; min-height: 320px; }
.hero-card::before { content:""; position:absolute; width:210px; height:210px; right:-80px; top:-80px; border-radius:999px; background: color-mix(in srgb, var(--brand) 22%, transparent); animation: floatBlob 6s ease-in-out infinite; }
.hero-card h2 { margin: 0 0 10px; font-size: clamp(34px, 7vw, 64px); line-height:.98; letter-spacing:-.05em; }
.hero-card p, .card-copy { color:var(--muted); line-height:1.7; }
.home-actions { display:flex; flex-wrap:wrap; gap:8px; margin-top:24px; }
.side-stack { display:grid; gap:14px; }
.glass-card { padding:20px; }
.glass-card h3 { margin:0 0 10px; }
.quick-grid { display:grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap:10px; margin-top:14px; }
.quick-link { padding:15px; border-radius:16px; background: var(--solid); border:1px solid var(--line); font-weight:900; transition:.18s ease; }
.quick-link:hover { transform: translateY(-2px); border-color:var(--brand); }

.quiz-card { padding: clamp(17px, 3vw, 28px); animation: liftIn .28s ease both; }
.question-meta { display:flex; flex-wrap:wrap; gap:7px; align-items:center; color:var(--muted); font-size:13px; margin-bottom:14px; }
.badge { display:inline-flex; align-items:center; gap:5px; background:var(--soft); border:1px solid var(--line); border-radius:999px; padding:7px 10px; font-weight:900; }
.badge.good { background: color-mix(in srgb, var(--good) 13%, var(--solid)); color:var(--good); border-color: color-mix(in srgb, var(--good) 34%, var(--line)); }
.badge.bad { background: color-mix(in srgb, var(--bad) 12%, var(--solid)); color:var(--bad); border-color: color-mix(in srgb, var(--bad) 34%, var(--line)); }
.badge.warn { background: color-mix(in srgb, var(--warn) 13%, var(--solid)); color:var(--warn); border-color: color-mix(in srgb, var(--warn) 34%, var(--line)); }
.badge.ai { background: color-mix(in srgb, var(--ai) 14%, var(--solid)); color:var(--ai); border-color: color-mix(in srgb, var(--ai) 34%, var(--line)); }
.question { margin:0 0 18px; font-size: clamp(22px, 3vw, 34px); line-height:1.36; white-space:pre-wrap; letter-spacing:-.02em; }
.options { display:grid; gap:10px; }
.option {
  display:grid; grid-template-columns: 42px minmax(0,1fr); gap:12px; align-items:start; width:100%; text-align:left;
  border:1px solid var(--line); background: var(--solid); color:var(--text); border-radius:18px; padding:15px;
  transition: transform .18s ease, border-color .18s ease, background-color .18s ease, box-shadow .18s ease;
}
.option:hover { transform: translateX(4px); border-color:var(--brand); box-shadow: 0 10px 24px color-mix(in srgb, var(--brand) 12%, transparent); }
.option .letter { display:grid; place-items:center; width:36px; height:36px; border-radius:13px; background: var(--soft); font-weight:950; }
.option.selected { border-color:var(--brand); background: color-mix(in srgb, var(--brand) 11%, var(--solid)); }
.option.correct { border-color: color-mix(in srgb, var(--good) 55%, var(--line)); background: color-mix(in srgb, var(--good) 13%, var(--solid)); }
.option.incorrect { border-color: color-mix(in srgb, var(--bad) 52%, var(--line)); background: color-mix(in srgb, var(--bad) 11%, var(--solid)); }
.option .text { line-height:1.65; }
.open-answer { min-height: 170px; resize: vertical; line-height:1.7; }
.answer-chips, .action-row, .nav-row, .ai-inline-row { display:flex; flex-wrap:wrap; gap:8px; }
.nav-row { margin-top:18px; justify-content:space-between; }
.answer-chip {
  border:1px solid var(--line); background:var(--solid); color:var(--text); border-radius:13px; padding:10px 13px; font-weight:900; transition:.16s ease;
}
.answer-chip.active { background: var(--brand); color:var(--bg); border-color:var(--brand); }
.reveal-grid { display:grid; gap:10px; margin-top:16px; }
.reveal { display:none; border:1px solid var(--line); border-radius:18px; padding:15px; background:var(--soft); line-height:1.68; white-space:normal; animation: fadeSlide .22s ease both; }
.reveal.visible { display:block; }
.reveal h3 { margin:0 0 8px; font-size:15px; }
.markdown { line-height:1.72; }
.markdown > *:first-child { margin-top:0; }
.markdown > *:last-child { margin-bottom:0; }
.markdown h1, .markdown h2, .markdown h3 { margin: 1em 0 .45em; line-height:1.25; }
.markdown p { margin:.65em 0; }
.markdown ul, .markdown ol { padding-left:1.3em; margin:.65em 0; }
.markdown blockquote { margin:.8em 0; padding: .7em 1em; border-left:4px solid var(--brand); background: color-mix(in srgb, var(--brand) 8%, transparent); border-radius: 0 12px 12px 0; }
.markdown code { padding:.14em .36em; border-radius:7px; background: color-mix(in srgb, var(--text) 8%, transparent); }
.markdown pre { overflow:auto; padding: 12px; border-radius:14px; background:#0f172a; color:#e5e7eb; }
.markdown table { width:100%; border-collapse:collapse; margin:.8em 0; font-size:14px; }
.markdown th, .markdown td { border:1px solid var(--line); padding:8px; text-align:left; }

.study-grid { display:grid; grid-template-columns: repeat(auto-fill, minmax(260px,1fr)); gap:12px; }
.study-card { padding:17px; transition:.18s ease; }
.study-card:hover { transform:translateY(-3px); border-color:var(--brand); }
.study-card h3 { margin:8px 0 9px; font-size:17px; line-height:1.35; }
.study-card p { color:var(--muted); line-height:1.6; margin:0 0 10px; }

.stat-grid { display:grid; grid-template-columns: repeat(4, 1fr); gap:12px; margin-bottom:14px; }
.stat-card { padding:18px; }
.stat-card b { display:block; font-size:28px; }
.stat-card span { color:var(--muted); font-size:13px; }
.table-wrap { overflow:auto; border:1px solid var(--line); border-radius:18px; background: var(--panel); box-shadow:var(--shadow); }
table.data-table { width:100%; border-collapse:collapse; min-width:760px; }
.data-table th, .data-table td { padding:13px 14px; border-bottom:1px solid var(--line); text-align:left; vertical-align:top; }
.data-table th { font-size:12px; color:var(--muted); letter-spacing:.06em; }
.rate-bar { height:9px; border-radius:999px; background:var(--soft); overflow:hidden; min-width:90px; }
.rate-bar span { display:block; height:100%; background:linear-gradient(90deg, var(--bad), var(--good)); border-radius:999px; }

.ai-tools-grid { display:grid; grid-template-columns: repeat(3, 1fr); gap:12px; margin-bottom:14px; }
.ai-tool-card { padding:18px; background:var(--panel); border:1px solid var(--line); border-radius:var(--radius); box-shadow:var(--shadow); }
.ai-tool-card h3 { margin:0 0 8px; }
.ai-tool-card p { color:var(--muted); line-height:1.6; min-height:50px; }
.inline-form { display:grid; gap:8px; }
.generated-box { margin-top:14px; }

.ai-drawer {
  position: fixed; top:0; right:0; height:100dvh; width:min(460px, 100vw); z-index:60;
  background: var(--solid); border-left:1px solid var(--line); box-shadow: -22px 0 55px rgba(0,0,0,.18);
  transform: translateX(105%); transition: transform .25s ease; display:grid; grid-template-rows:auto 1fr auto auto auto; gap:10px; padding:16px;
}
.ai-drawer.open { transform:translateX(0); }
.ai-drawer-head { display:flex; align-items:center; justify-content:space-between; gap:12px; }
.ai-drawer-head h2 { margin:0; }
.ai-drawer-head p, .drawer-note { margin:3px 0 0; color:var(--muted); font-size:13px; line-height:1.55; }
.ai-chat-log { overflow:auto; display:flex; flex-direction:column; gap:10px; padding:10px; background:var(--soft); border:1px solid var(--line); border-radius:18px; }
.chat-msg { max-width:92%; padding:12px 13px; border-radius:17px; animation: fadeSlide .18s ease both; }
.chat-msg.user { align-self:flex-end; background:var(--brand); color:var(--bg); border-bottom-right-radius:6px; }
.chat-msg.assistant { align-self:flex-start; background:var(--solid); border:1px solid var(--line); border-bottom-left-radius:6px; }
.chat-msg.system { align-self:center; color:var(--muted); text-align:center; font-size:14px; }
.ai-chat-input { resize:vertical; min-height:88px; }
.ai-drawer-actions { display:grid; grid-template-columns:1fr auto auto; gap:8px; }
.drawer-backdrop { position:fixed; inset:0; z-index:55; background:rgba(0,0,0,.28); opacity:0; pointer-events:none; transition:.22s ease; }
.drawer-backdrop.open { opacity:1; pointer-events:auto; }
.switch-row {
  display:flex; align-items:center; gap:9px; border:1px solid var(--line); border-radius:999px; background:var(--solid); color:var(--text); padding:9px 11px; font-weight:850; justify-self:start;
}
.switch-dot { width:34px; height:20px; border-radius:999px; background:var(--line); position:relative; transition:.18s ease; }
.switch-dot::after { content:""; width:16px; height:16px; border-radius:999px; background:#fff; position:absolute; top:2px; left:2px; transition:.18s ease; box-shadow:0 2px 5px rgba(0,0,0,.22); }
.switch-row.is-on .switch-dot { background:var(--brand); }
.switch-row.is-on .switch-dot::after { transform:translateX(14px); }
.floating-ai {
  position:fixed; right:16px; bottom:16px; z-index:45; border:0; border-radius:999px; padding:14px 18px; font-weight:950; color:#fff;
  background:linear-gradient(135deg, var(--ai), var(--brand)); box-shadow:0 18px 35px color-mix(in srgb, var(--ai) 30%, transparent);
}
.toast { position:fixed; left:50%; bottom:18px; transform:translate(-50%, 12px); opacity:0; z-index:80; max-width:min(520px, calc(100vw - 30px)); padding:13px 15px; border-radius:14px; background:#0f172a; color:#fff; box-shadow:0 18px 40px rgba(0,0,0,.25); transition:.22s ease; pointer-events:none; }
.toast.show { opacity:1; transform:translate(-50%,0); }
.empty { text-align:center; padding:58px 18px; color:var(--muted); }
.footer-note { color:var(--muted); font-size:12px; line-height:1.6; margin-top:12px; }
.kbd { border:1px solid var(--line); border-bottom-width:2px; border-radius:7px; padding:1px 6px; background:var(--solid); font-size:12px; color:var(--muted); }

@keyframes fadeSlide { from { opacity:0; transform:translateY(8px); } to { opacity:1; transform:translateY(0); } }
@keyframes liftIn { from { opacity:0; transform:translateY(10px) scale(.99); } to { opacity:1; transform:translateY(0) scale(1); } }
@keyframes pop { from { opacity:0; transform:translateY(-4px) scale(.98); } to { opacity:1; transform:translateY(0) scale(1); } }
@keyframes floatBlob { 0%,100% { transform:translate(0,0) scale(1); } 50% { transform:translate(-16px,18px) scale(1.08); } }

@media (max-width: 980px) {
  .site-head { grid-template-columns: 1fr auto; }
  .brand { min-width:0; }
  .page-nav { grid-column:1 / -1; justify-content:flex-start; order:3; }
  .filter-panel { grid-template-columns: 1fr 1fr; }
  .search-wrap { grid-column:1 / -1; }
  .home-grid, .ai-tools-grid { grid-template-columns:1fr; }
  .stat-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .site-head { padding:9px 10px; gap:8px; }
  .brand-mark { width:36px; height:36px; border-radius:13px; }
  .brand b { font-size:13px; }
  .brand small { display:none; }
  .head-actions .icon-action { display:none; }
  .nav-pill { padding:9px 11px; font-size:13px; }
  .mobile-title { padding:12px 12px 8px; }
  .mobile-title h1 { font-size:26px; }
  .mobile-title p { display:none; }
  .stat-strip { grid-template-columns:repeat(4, minmax(72px,1fr)); overflow-x:auto; padding:0 12px 8px; gap:7px; }
  .stat-strip div { padding:10px; border-radius:15px; min-width:72px; }
  .stat-strip b { font-size:18px; }
  .toolbar-row { padding:0 12px 8px; }
  .filter-panel { grid-template-columns:1fr; padding:0 12px 10px; }
  .page-main { padding:0 12px 88px; }
  .quiz-card { padding:16px; border-radius:20px; }
  .question { font-size:22px; margin-bottom:14px; }
  .option { grid-template-columns:38px 1fr; padding:13px; border-radius:16px; }
  .nav-row { display:grid; grid-template-columns:1fr; }
  .nav-row .right, .nav-row .left { display:grid; grid-template-columns:1fr 1fr; gap:8px; }
  .btn { width:100%; }
  .floating-ai { right:12px; bottom:12px; }
  .ai-drawer { width:100vw; padding:12px; }
  .ai-drawer-actions { grid-template-columns:1fr 1fr; }
  .ai-drawer-actions .ai-btn { grid-column:1 / -1; }
  .quick-grid { grid-template-columns:1fr; }
  .stat-grid { grid-template-columns:1fr; }
}
@media print {
  .site-head, .toolbar-row, .filter-panel, .floating-ai, .ai-drawer, .drawer-backdrop, .nav-row { display:none !important; }
  body { background:#fff; }
  .page-main { padding:0; }
  .quiz-card { box-shadow:none; border:0; }
  .reveal { display:block !important; }
}

/* Polish layer */
.fa-solid, .fa-regular, .fa-brands { line-height: 1; }
.btn, .nav-pill, .icon-action, .quick-link, .switch-row, .option-item { display: inline-flex; align-items: center; justify-content: center; gap: .55em; }
.btn span, .nav-pill span, .quick-link span { position: relative; z-index: 1; }
.brand-mark { font-size: 18px; }
.brand-mark::after { content:""; position:absolute; inset:-4px; border-radius:18px; border:1px solid color-mix(in srgb, var(--brand) 28%, transparent); animation: softPulse 2.8s ease-in-out infinite; }
.site-head { box-shadow: 0 10px 30px rgba(22,35,28,.04); }
.stat-strip div { position: relative; overflow: hidden; }
.stat-strip div > .fa-solid { position: absolute; right: 12px; top: 12px; color: color-mix(in srgb, var(--brand) 38%, transparent); font-size: 18px; }
.toolbar-row .btn { min-width: 112px; }
.select-trigger { display: flex; align-items:center; justify-content:space-between; gap: 8px; position: relative; }
.select-trigger::after { content: none; }
.select-trigger .fa-chevron-down { color: var(--muted); font-size: 12px; transition: transform .18s ease; }
.selectish.open .select-trigger .fa-chevron-down { transform: rotate(180deg); }
.option-item { justify-content: flex-start; }
.option-item .fa-solid { width: 16px; color: color-mix(in srgb, var(--brand) 64%, var(--muted)); }
.hero-card .fa-location-dot, .glass-card h3 .fa-solid, .ai-tool-card h3 .fa-solid { color: var(--brand); }
.quick-link { justify-content: flex-start; }
.quick-link .fa-solid { color: var(--brand); }
.question { position: relative; }
.reveal h3, .generated-detail summary { display:flex; align-items:center; gap:.55em; }
.reveal h3 .fa-solid { color: var(--brand); }
.icon-btn .fa-solid { font-size: 18px; }
.floating-ai { display: inline-flex; align-items:center; gap:8px; }
.ai-drawer { grid-template-rows: auto 1fr auto auto; }
.ai-drawer-head h2 { display:flex; align-items:center; gap:.55em; }
.ai-drawer-head h2 .fa-solid { color: var(--ai); }
.chat-msg { animation: none; }
.chat-msg.system { display:flex; align-items:center; justify-content:center; gap:.5em; }
.stream-text { white-space: pre-wrap; overflow-wrap: anywhere; }
.stream-chunk { display:inline; animation: tokenFade .28s ease both; }
.typing-line { display:inline-flex; align-items:center; gap:.55em; color:var(--muted); }
.generated-list { display:grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap:14px; }
.generated-card { background: var(--solid); border:1px solid var(--line); border-radius:20px; padding:16px; box-shadow: 0 12px 28px rgba(22,35,28,.07); animation: liftIn .22s ease both; }
.generated-card h3 { margin:10px 0 12px; font-size:18px; line-height:1.45; }
.generated-options { display:grid; gap:8px; margin: 10px 0 12px; }
.generated-option { display:grid; grid-template-columns: 34px 1fr; gap:8px; align-items:start; border:1px solid var(--line); border-radius:14px; padding:10px; background:var(--soft); }
.generated-option span { width:28px; height:28px; border-radius:10px; display:grid; place-items:center; background:var(--solid); font-weight:950; }
.generated-option p { margin:0; line-height:1.55; }
.generated-option.correct { border-color: color-mix(in srgb, var(--good) 45%, var(--line)); background: color-mix(in srgb, var(--good) 10%, var(--solid)); }
.generated-detail { border-top:1px dashed var(--line); padding-top:10px; }
.generated-detail summary { cursor:pointer; font-weight:900; color:var(--brand-dark); }
.tool-status { display:flex; align-items:center; justify-content:center; gap:10px; min-height: 140px; color:var(--muted); font-weight:900; }
.answer-chip { display:inline-flex; align-items:center; justify-content:center; }
@keyframes tokenFade { from { opacity:0; transform: translateY(4px); filter: blur(2px); } to { opacity:1; transform: translateY(0); filter: blur(0); } }
@keyframes softPulse { 0%,100% { opacity:.18; transform:scale(.96); } 50% { opacity:.55; transform:scale(1.06); } }

@media (max-width: 640px) {
  .toolbar-row { display:grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap:7px; }
  .toolbar-row .btn { min-width:0; padding:10px 8px; }
  .toolbar-row .btn span { font-size: 12px; }
  .stat-strip div > .fa-solid { display:none; }
  .generated-list { grid-template-columns:1fr; }
  .chat-msg { max-width: 96%; }
}
.brand-mark { position: relative; }
.generated-detail h4 { margin:0 0 8px; display:flex; align-items:center; gap:.55em; color:var(--brand-dark); }


/* Final mobile/filter polish */
.toolbar-row, .filter-panel { position: relative; z-index: 48; }
.page-main { position: relative; z-index: 1; }
.filter-panel {
  display: grid !important;
  max-height: 0;
  opacity: 0;
  transform: translateY(-10px);
  overflow: hidden;
  pointer-events: none;
  padding-top: 0 !important;
  padding-bottom: 0 !important;
  transition: max-height .34s cubic-bezier(.2,.8,.2,1), opacity .22s ease, transform .28s ease, padding .28s ease;
}
.filter-panel.open {
  max-height: 520px;
  opacity: 1;
  transform: translateY(0);
  overflow: visible;
  pointer-events: auto;
  padding-top: 0 !important;
  padding-bottom: 14px !important;
}
#filterToggle.active { border-color: color-mix(in srgb, var(--brand) 48%, var(--line)); background: color-mix(in srgb, var(--brand) 12%, var(--solid)); color: var(--brand-dark); }
.selectish { z-index: 1; }
.selectish.open { z-index: 90; }
.select-menu {
  z-index: 160;
  display: block;
  visibility: hidden;
  opacity: 0;
  pointer-events: none;
  transform-origin: top center;
  transform: translateY(-8px) scaleY(.94);
  max-height: min(270px, 52vh);
  transition: opacity .18s ease, transform .22s cubic-bezier(.2,.8,.2,1), visibility 0s linear .22s;
  animation: none !important;
}
.selectish.open .select-menu {
  visibility: visible;
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0) scaleY(1);
  transition-delay: 0s;
}
.nav-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  justify-content: stretch;
}
.primary-action-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}
.secondary-action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.primary-action-row .btn { min-height: 44px; }
.secondary-action-row .btn { flex: 0 1 auto; }
.ai-chat-input::placeholder { opacity: .68; transition: opacity .18s ease; }
.ai-chat-input.placeholder-swapping::placeholder { opacity: 0; }

@media (max-width: 640px) {
  .filter-panel.open { max-height: 760px; padding-bottom: 10px !important; }
  .select-menu { margin-top: 7px; max-height: 42vh; box-shadow: 0 14px 32px rgba(22,35,28,.12); }
  .primary-action-row { order: 1; }
  .secondary-action-row { order: 2; display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); }
  .secondary-action-row .btn { width: 100%; }
  .footer-note { margin-bottom: 0; }
}

.generated-quiz-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
  animation: fadeSlide .22s ease both;
}
.generated-box > .quiz-card,
.generated-box .quiz-card {
  margin-top: 10px;
}
.generated-box .quiz-card {
  box-shadow: none;
  background: color-mix(in srgb, var(--panel) 82%, transparent);
}
@media (max-width: 640px) {
  .generated-quiz-top {
    display: grid;
    grid-template-columns: 1fr;
    align-items: stretch;
  }
  .generated-quiz-top .btn { width: 100%; }
}


/* Dropdown / action layout refinement */
.site-head { z-index: 700; }
.toolbar-row { position: relative; z-index: 760; }
.filter-panel { position: relative; z-index: 780; }
.filter-panel.open { z-index: 820; }
.page-main { position: relative; z-index: 1; }
.quiz-card { position: relative; z-index: 1; }

.filter-panel {
  transform: none !important;
  will-change: max-height, opacity;
}
.filter-panel > * {
  opacity: 0;
  transform: translateY(-8px);
}
.filter-panel.open > * {
  animation: dropdownItemDrop .28s cubic-bezier(.2,.8,.2,1) both;
}
.filter-panel.open > *:nth-child(1) { animation-delay: 20ms; }
.filter-panel.open > *:nth-child(2) { animation-delay: 55ms; }
.filter-panel.open > *:nth-child(3) { animation-delay: 90ms; }
.filter-panel.open > *:nth-child(4) { animation-delay: 125ms; }
.filter-panel.open > *:nth-child(5) { animation-delay: 160ms; }
.filter-panel.open > *:nth-child(6) { animation-delay: 195ms; }

.selectish { position: relative; z-index: 2; }
.selectish.open { z-index: 1200; }
.select-menu {
  z-index: 1300 !important;
  transform: none !important;
  transform-origin: top center;
  max-height: 0;
  opacity: 0;
  clip-path: inset(0 0 100% 0 round 16px);
  overflow: hidden auto;
  transition: max-height .26s cubic-bezier(.2,.8,.2,1), opacity .18s ease, clip-path .26s cubic-bezier(.2,.8,.2,1), visibility 0s linear .26s;
  box-shadow: 0 20px 44px rgba(22,35,28,.16), 0 0 0 1px color-mix(in srgb, var(--line) 84%, transparent);
}
.selectish.open .select-menu {
  max-height: min(310px, 54vh);
  opacity: 1;
  clip-path: inset(0 0 0 0 round 16px);
  visibility: visible;
  pointer-events: auto;
  transition-delay: 0s;
}
.select-menu .option-item {
  opacity: 0;
  transform: translateY(-7px);
  animation: none;
}
.selectish.open .select-menu .option-item {
  animation: dropdownItemDrop .22s cubic-bezier(.2,.8,.2,1) both;
  animation-delay: calc(var(--drop-i, 0) * 34ms + 35ms);
}

.nav-row {
  display: grid !important;
  grid-template-columns: minmax(0,1fr);
  gap: 10px;
}
.primary-action-row {
  display: grid !important;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 10px;
}
.primary-action-row .btn,
.secondary-action-row .btn { min-width: 0; }

@media (max-width: 640px) {
  .toolbar-row { grid-template-columns: repeat(3, minmax(0,1fr)); }
  .filter-panel.open { max-height: 880px; overflow: visible; }
  .filter-panel:not(.open) { overflow: hidden; }
  .selectish.open .select-menu { max-height: min(330px, 50vh); }
  .primary-action-row,
  .secondary-action-row {
    display: grid !important;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 8px;
    width: 100%;
  }
  .primary-action-row { order: 1; }
  .secondary-action-row { order: 2; }
  .primary-action-row .btn,
  .secondary-action-row .btn {
    width: 100%;
    justify-content: center;
    min-height: 45px;
  }
}

@keyframes dropdownItemDrop {
  from { opacity: 0; transform: translateY(-9px); filter: blur(2px); }
  to { opacity: 1; transform: translateY(0); filter: blur(0); }
}


/* Quiz spacing and option dropdown animation */
.quiz-progress-top {
  display: grid;
  gap: 9px;
  margin: 0 0 22px;
  padding: 14px 15px;
  border: 1px solid color-mix(in srgb, var(--brand) 22%, var(--line));
  border-radius: 18px;
  background: color-mix(in srgb, var(--brand) 7%, var(--solid));
}
.quiz-progress-info {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-weight: 900;
  font-size: 13px;
}
.quiz-progress-info span {
  display: inline-flex;
  align-items: center;
  gap: .55em;
}
.quiz-progress-info i { color: var(--brand); }
.quiz-progress-info b {
  color: var(--brand-dark);
  font-size: 14px;
}
.quiz-progress-track {
  height: 10px;
  overflow: hidden;
  border-radius: 999px;
  background: color-mix(in srgb, var(--line) 62%, transparent);
  box-shadow: inset 0 1px 3px rgba(0,0,0,.08);
}
.quiz-progress-track span {
  display: block;
  height: 100%;
  width: 0;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--brand), var(--brand-2), var(--ai));
  transition: width .36s cubic-bezier(.2,.8,.2,1);
}
.quiz-card { padding-top: clamp(20px, 3.4vw, 32px); }
.question-meta { margin-bottom: 18px; row-gap: 9px; }
.question { margin-bottom: 26px; }
.options { gap: 14px; }
.option { padding: 17px; }
.reveal-grid { gap: 13px; margin-top: 20px; }
.nav-row { margin-top: 24px; gap: 12px; }
.option-drop .option {
  opacity: 0;
  transform: translateY(-12px);
  animation: quizOptionDrop .34s cubic-bezier(.2,.8,.2,1) both;
  animation-delay: calc(var(--option-i, 0) * 58ms + 45ms);
}
.option-drop .option:nth-child(1) { --option-i: 0; }
.option-drop .option:nth-child(2) { --option-i: 1; }
.option-drop .option:nth-child(3) { --option-i: 2; }
.option-drop .option:nth-child(4) { --option-i: 3; }
.option-drop .option:nth-child(5) { --option-i: 4; }
@keyframes quizOptionDrop {
  from { opacity: 0; transform: translateY(-14px); filter: blur(3px); }
  to { opacity: 1; transform: translateY(0); filter: blur(0); }
}
@media (max-width: 640px) {
  .quiz-progress-top {
    margin-bottom: 18px;
    padding: 12px;
    border-radius: 16px;
  }
  .question-meta { margin-bottom: 16px; }
  .question { margin-bottom: 22px; }
  .options { gap: 12px; }
  .option { padding: 14px; }
  .nav-row { margin-top: 22px; }
}

/* Top bar stability fix */
.site-head {
  position: sticky !important;
  top: 0 !important;
  z-index: 3200 !important;
  width: 100% !important;
  max-width: none !important;
  margin: 0 !important;
  padding-left: max(14px, calc((100vw - 1180px) / 2 + 16px)) !important;
  padding-right: max(14px, calc((100vw - 1180px) / 2 + 16px)) !important;
  background: color-mix(in srgb, var(--bg) 92%, transparent) !important;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 82%, transparent) !important;
  box-shadow: 0 14px 36px rgba(22,35,28,.08) !important;
  isolation: isolate;
  overflow: visible;
}
.site-head::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  background: inherit;
}
.site-head .brand,
.site-head .page-nav,
.site-head .head-actions {
  position: relative;
  z-index: 1;
  pointer-events: auto;
}
.site-head .nav-pill,
.site-head .icon-action,
.site-head .btn {
  pointer-events: auto;
}
.mobile-title,
.stat-strip,
.toolbar-row,
.filter-panel,
.page-main {
  position: relative;
}
.toolbar-row { z-index: 1100 !important; }
.filter-panel { z-index: 1150 !important; }
.filter-panel.open { z-index: 1200 !important; }
.selectish.open { z-index: 1250 !important; }
.select-menu { z-index: 1260 !important; }
.page-main,
.quiz-card,
.study-card,
.stat-card,
.glass-card,
.generated-box,
.generated-box .quiz-card {
  z-index: auto !important;
}
.drawer-backdrop { z-index: 4300 !important; }
.ai-drawer { z-index: 4400 !important; }
.floating-ai { z-index: 2100 !important; }
.toast { z-index: 5200 !important; }

@media (max-width: 980px) {
  .site-head {
    padding-left: 12px !important;
    padding-right: 12px !important;
  }
}
@media (max-width: 640px) {
  .site-head {
    top: 0 !important;
    padding: calc(8px + env(safe-area-inset-top, 0px)) 10px 9px !important;
    grid-template-columns: minmax(0, 1fr) auto !important;
  }
  .page-nav {
    position: relative;
    z-index: 2;
  }
  .mobile-title { padding-top: 14px; }
}

/* Overlay stability patch: dropdowns expand in-flow, buttons stay clickable */
html, body { overflow-x: clip; }
.site-head { z-index: 3000 !important; }
.toolbar-row { z-index: 120 !important; }
.filter-panel {
  position: relative !important;
  z-index: 130 !important;
  overflow: hidden !important;
  isolation: isolate;
}
.filter-panel.open {
  z-index: 140 !important;
  overflow: visible !important;
  max-height: 1800px !important;
}
.filter-panel > *,
.custom-field,
.selectish,
.search-wrap {
  position: relative;
  z-index: auto !important;
  overflow: visible;
}
.selectish.open { z-index: 5 !important; }
.select-menu {
  position: static !important;
  inset: auto !important;
  z-index: auto !important;
  display: block !important;
  width: 100% !important;
  margin: 7px 0 0 !important;
  max-height: 0 !important;
  visibility: hidden !important;
  opacity: 0 !important;
  pointer-events: none !important;
  overflow: hidden !important;
  transform: none !important;
  clip-path: inset(0 0 100% 0 round 16px) !important;
  transition:
    max-height .28s cubic-bezier(.2,.8,.2,1),
    opacity .18s ease,
    clip-path .28s cubic-bezier(.2,.8,.2,1),
    margin .18s ease,
    visibility 0s linear .28s !important;
}
.selectish.open .select-menu {
  max-height: min(320px, 46vh) !important;
  visibility: visible !important;
  opacity: 1 !important;
  pointer-events: auto !important;
  overflow-y: auto !important;
  clip-path: inset(0 0 0 0 round 16px) !important;
  transition-delay: 0s !important;
}
.select-menu .option-item {
  opacity: 0;
  transform: translateY(-8px);
  pointer-events: auto;
}
.selectish.open .select-menu .option-item {
  animation: dropdownItemDrop .22s cubic-bezier(.2,.8,.2,1) both !important;
  animation-delay: calc(var(--drop-i, 0) * 32ms + 28ms) !important;
}
.page-main,
.quiz-card,
.generated-box,
.generated-box .quiz-card,
.study-card,
.stat-card,
.glass-card,
.table-wrap {
  position: relative;
  z-index: 0 !important;
  overflow: visible;
}
.quiz-card { isolation: auto; }
.btn,
.icon-action,
.icon-btn,
.option,
.answer-chip,
.select-trigger,
.option-item {
  position: relative;
  z-index: 0;
  pointer-events: auto;
  touch-action: manipulation;
}
.btn { isolation: isolate; }
.btn::after {
  z-index: 0;
  pointer-events: none;
}
.btn > i,
.btn > span,
.icon-action > i,
.icon-action > span,
.select-trigger > span,
.select-trigger > i {
  position: relative;
  z-index: 1;
  pointer-events: none;
}
.nav-row,
.primary-action-row,
.secondary-action-row {
  position: relative;
  z-index: 1;
}
.drawer-backdrop { z-index: 4300 !important; }
.ai-drawer { z-index: 4400 !important; }
.toast { z-index: 5200 !important; }
.floating-ai { z-index: 900 !important; pointer-events: auto; }
@media (max-width: 640px) {
  .filter-panel.open { max-height: 2100px !important; }
  .selectish.open .select-menu { max-height: min(340px, 42vh) !important; }
  .toolbar-row,
  .filter-panel,
  .page-main { transform: none !important; }
  .page-main { padding-bottom: 132px !important; }
  .floating-ai { bottom: calc(14px + env(safe-area-inset-bottom, 0px)) !important; right: 12px !important; }
  .primary-action-row,
  .secondary-action-row { grid-template-columns: repeat(2, minmax(0, 1fr)) !important; }
  .primary-action-row .btn,
  .secondary-action-row .btn { min-height: 46px; }
}
@media print {
  .filter-panel { display: none !important; }
}

/* Final polish: centred filter search, single-line controls, restored glass header */
.site-head {
  top: max(8px, env(safe-area-inset-top, 0px)) !important;
  width: min(1180px, calc(100% - 24px)) !important;
  max-width: 1180px !important;
  margin: 8px auto 0 !important;
  padding: 10px 14px !important;
  border-radius: 24px !important;
  border: 1px solid color-mix(in srgb, var(--line) 72%, transparent) !important;
  background: color-mix(in srgb, var(--solid) 58%, transparent) !important;
  box-shadow:
    0 20px 54px rgba(22,35,28,.12),
    inset 0 1px 0 rgba(255,255,255,.42) !important;
  backdrop-filter: blur(24px) saturate(1.22) !important;
  -webkit-backdrop-filter: blur(24px) saturate(1.22) !important;
}
html[data-theme="dark"] .site-head {
  background: color-mix(in srgb, var(--solid) 68%, transparent) !important;
  box-shadow:
    0 20px 54px rgba(0,0,0,.32),
    inset 0 1px 0 rgba(255,255,255,.08) !important;
}
.site-head::before {
  border-radius: inherit !important;
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--brand) 10%, transparent), transparent 36%),
    linear-gradient(180deg, rgba(255,255,255,.16), transparent) !important;
  backdrop-filter: none !important;
  -webkit-backdrop-filter: none !important;
}
.brand { min-width: 0 !important; }
.brand span:last-child { min-width: 0; }
.brand b,
.brand small,
.nav-pill span,
.icon-action span,
.btn span,
.select-trigger,
.option-item,
.answer-chip,
.stat-strip span,
.custom-field > span {
  white-space: nowrap !important;
  overflow: hidden !important;
  text-overflow: ellipsis !important;
}
.nav-pill,
.icon-action,
.btn,
.select-trigger,
.option-item,
.answer-chip {
  display: inline-flex !important;
  align-items: center !important;
  justify-content: center !important;
  gap: .5em !important;
  min-width: 0 !important;
  line-height: 1.18 !important;
}
.select-trigger,
.option-item {
  justify-content: flex-start !important;
}
.select-trigger {
  max-width: 100% !important;
  padding-right: 40px !important;
}
.select-trigger::after { flex: 0 0 auto; }
.filter-panel {
  align-items: end !important;
  justify-items: stretch !important;
}
.filter-panel .search-wrap {
  grid-column: 1 / -1 !important;
  width: min(100%, 760px) !important;
  justify-self: center !important;
}
.search-input {
  min-height: 48px !important;
  text-align: center !important;
  padding-left: 46px !important;
  padding-right: 46px !important;
}
.search-icon { left: 18px !important; }
.toolbar-row {
  justify-content: center !important;
  align-items: center !important;
}
.toolbar-row .btn {
  max-width: 100% !important;
}
.stat-strip div,
.glass-card,
.quiz-card,
.study-card,
.stat-card,
.ai-tool-card {
  backdrop-filter: blur(16px) saturate(1.08);
  -webkit-backdrop-filter: blur(16px) saturate(1.08);
}
@media (min-width: 981px) {
  .filter-panel {
    grid-template-columns: repeat(4, minmax(145px, 1fr)) minmax(120px, .75fr) auto !important;
  }
}
@media (max-width: 980px) {
  .site-head {
    width: calc(100% - 20px) !important;
    padding: 9px 10px !important;
    border-radius: 20px !important;
  }
  .filter-panel .search-wrap {
    grid-column: 1 / -1 !important;
    width: 100% !important;
  }
}
@media (max-width: 640px) {
  .site-head {
    width: calc(100% - 16px) !important;
    margin-top: 8px !important;
    border-radius: 18px !important;
    grid-template-columns: minmax(0, 1fr) auto !important;
  }
  .brand-mark { width: 38px !important; height: 38px !important; border-radius: 14px !important; }
  .brand b { font-size: 13px !important; }
  .brand small { font-size: 11px !important; }
  .page-nav { padding: 4px 2px !important; }
  .nav-pill { padding: 9px 10px !important; font-size: 12px !important; }
  .head-actions { gap: 6px !important; }
  .head-actions .btn,
  .head-actions .icon-action { padding: 9px 10px !important; }
  .head-actions .btn span,
  .head-actions .icon-action span { max-width: 3.2em !important; }
  .toolbar-row .btn span { max-width: 5em !important; }
  .filter-panel { justify-items: center !important; }
  .filter-panel > * { width: 100% !important; }
  .search-input { text-align: center !important; }
  .custom-field > span { max-width: 100%; }
}