:root{
  --bg:#f4f6fb;--surface:#ffffff;--surface-2:#f0f3f9;--border:#e3e8f0;
  --text:#0f172a;--muted:#64748b;--primary:#2563eb;--primary-600:#1d4ed8;--primary-soft:#dbeafe;
  --accent:#7c3aed;--accent-soft:#ede9fe;--green:#16a34a;--green-soft:#dcfce7;
  --red:#dc2626;--red-soft:#fee2e2;--amber:#d97706;--amber-soft:#fef3c7;--teal:#0d9488;--teal-soft:#ccfbf1;
  --shadow:0 1px 2px rgba(15,23,42,.05),0 4px 16px rgba(15,23,42,.06);
  --shadow-lg:0 10px 40px rgba(15,23,42,.14);--radius:14px;--sidebar-w:250px;
}
[data-theme="dark"]{
  --bg:#0b1020;--surface:#141a2e;--surface-2:#1b2340;--border:#26304f;
  --text:#e7ecf7;--muted:#93a0bd;--primary:#5b8cff;--primary-600:#4a79f0;--primary-soft:#1e2c55;
  --accent:#a78bfa;--accent-soft:#2b2352;--green:#4ade80;--green-soft:#153524;
  --red:#f87171;--red-soft:#3b1c1c;--amber:#fbbf24;--amber-soft:#3a2d0f;--teal:#2dd4bf;--teal-soft:#0f2f2b;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 4px 16px rgba(0,0,0,.35);--shadow-lg:0 10px 40px rgba(0,0,0,.5);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;height:100%}
body{font-family:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text);font-size:15px;line-height:1.5;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer;color:inherit}
input,select,textarea{font-family:inherit;font-size:14px;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:10px 12px;outline:none;transition:border .15s,box-shadow .15s}
input:focus,select:focus,textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px var(--primary-soft)}
.hidden{display:none!important}
.mono{font-family:'JetBrains Mono',monospace}

#app{display:flex;min-height:100vh}
#sidebar{width:var(--sidebar-w);background:var(--surface);border-right:1px solid var(--border);display:flex;flex-direction:column;position:fixed;top:0;bottom:0;left:0;z-index:40;transition:transform .25s}
.brand{display:flex;align-items:center;gap:12px;padding:22px 20px 14px}
.brand-logo{width:40px;height:40px;border-radius:12px;background:linear-gradient(135deg,var(--primary),var(--accent));color:#fff;font-weight:800;font-size:20px;display:grid;place-items:center;box-shadow:var(--shadow)}
.brand-name{font-weight:700;font-size:16px;letter-spacing:-.2px}
.brand-sub{font-size:12px;color:var(--muted)}
.nav{display:flex;flex-direction:column;gap:2px;padding:8px 12px}
.nav-link{display:flex;align-items:center;gap:10px;padding:10px 12px;border-radius:10px;color:var(--muted);font-weight:500;font-size:14px;transition:all .15s}
.nav-link:hover{background:var(--surface-2);color:var(--text)}
.nav-link.active{background:var(--primary-soft);color:var(--primary);font-weight:600}
.nav-ico{width:20px;text-align:center;font-size:15px}
.badge{margin-left:auto;background:var(--red);color:#fff;font-size:11px;font-weight:700;padding:2px 8px;border-radius:999px}
.sidebar-foot{margin-top:auto;padding:16px 20px;border-top:1px solid var(--border)}
.streak-box{display:flex;align-items:baseline;gap:8px}
.streak-num{font-size:28px;font-weight:800;color:var(--amber)}
.streak-lbl{font-size:13px;color:var(--muted)}
.refs-note{font-size:11px;color:var(--muted);margin-top:8px;line-height:1.4}

#main-wrap{flex:1;margin-left:var(--sidebar-w);display:flex;flex-direction:column;min-width:0}
#topbar{display:flex;align-items:center;gap:14px;padding:14px 28px;background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:30}
.topbar-search{flex:1;max-width:560px}
.topbar-search input{width:100%;background:var(--surface-2);border-color:transparent}
.topbar-actions{margin-left:auto;display:flex;gap:6px}
.icon-btn{width:38px;height:38px;border-radius:10px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:16px;display:grid;place-items:center;transition:all .15s}
.icon-btn:hover{background:var(--surface-2)}
#menu-btn{display:none}
main#view{padding:28px;max-width:1200px;width:100%;margin:0 auto;animation:fade .25s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

h1{font-size:28px;font-weight:800;letter-spacing:-.5px;margin:0 0 6px}
h2{font-size:20px;font-weight:700;margin:0 0 12px;letter-spacing:-.3px}
h3{font-size:16px;font-weight:700;margin:0 0 8px}
.sub{color:var(--muted);margin:0 0 22px;font-size:15px}
.page-head{display:flex;align-items:flex-start;justify-content:space-between;gap:16px;flex-wrap:wrap;margin-bottom:20px}
.row{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.grid{display:grid;gap:16px}
.grid-2{grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}
.grid-3{grid-template-columns:repeat(auto-fill,minmax(240px,1fr))}
.grid-4{grid-template-columns:repeat(auto-fill,minmax(200px,1fr))}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.card.clickable{cursor:pointer;transition:transform .15s,box-shadow .15s,border-color .15s}
.card.clickable:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg);border-color:var(--primary)}
.section{margin-bottom:32px}

.btn{display:inline-flex;align-items:center;gap:8px;padding:10px 16px;border-radius:10px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-weight:600;font-size:14px;transition:all .15s;white-space:nowrap}
.btn:hover{background:var(--surface-2);border-color:var(--muted)}
.btn.primary{background:var(--primary);border-color:var(--primary);color:#fff}
.btn.primary:hover{background:var(--primary-600)}
.btn.accent{background:var(--accent);border-color:var(--accent);color:#fff}
.btn.ghost{border-color:transparent;background:transparent}
.btn.sm{padding:6px 11px;font-size:13px}
.btn.lg{padding:14px 22px;font-size:16px}
.btn.danger{color:var(--red);border-color:var(--red)}
.btn:disabled{opacity:.5;cursor:not-allowed}
.btn.block{width:100%;justify-content:center}

.chip{display:inline-flex;align-items:center;gap:4px;padding:3px 10px;border-radius:999px;font-size:12px;font-weight:600;background:var(--surface-2);color:var(--muted);border:1px solid var(--border)}
.chip.primary{background:var(--primary-soft);color:var(--primary);border-color:transparent}
.chip.accent{background:var(--accent-soft);color:var(--accent);border-color:transparent}
.chip.green{background:var(--green-soft);color:var(--green);border-color:transparent}
.chip.red{background:var(--red-soft);color:var(--red);border-color:transparent}
.chip.amber{background:var(--amber-soft);color:var(--amber);border-color:transparent}
.chip.teal{background:var(--teal-soft);color:var(--teal);border-color:transparent}
.chip.clickable{cursor:pointer}
.chip.clickable:hover{border-color:var(--primary)}

.stat-tiles{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:14px;margin-bottom:24px}
.tile{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px;box-shadow:var(--shadow)}
.tile-val{font-size:30px;font-weight:800;letter-spacing:-1px;line-height:1}
.tile-lbl{font-size:13px;color:var(--muted);margin-top:6px;font-weight:500}
.tile.c-primary .tile-val{color:var(--primary)}.tile.c-green .tile-val{color:var(--green)}
.tile.c-amber .tile-val{color:var(--amber)}.tile.c-red .tile-val{color:var(--red)}.tile.c-accent .tile-val{color:var(--accent)}

.progress{height:8px;background:var(--surface-2);border-radius:999px;overflow:hidden}
.progress > div{height:100%;background:linear-gradient(90deg,var(--primary),var(--accent));border-radius:999px;transition:width .4s}
.progress.green > div{background:var(--green)}
.progress.multi{display:flex}
.progress.multi > div{transition:width .4s;border-radius:0}

.deck-card{display:flex;flex-direction:column;gap:10px}
.deck-top{display:flex;align-items:center;gap:12px}
.deck-icon{width:44px;height:44px;border-radius:12px;display:grid;place-items:center;font-size:22px;background:var(--surface-2);flex-shrink:0}
.deck-title{font-weight:700;font-size:15px;line-height:1.3}
.deck-cat{font-size:12px;color:var(--muted);font-weight:500}
.deck-desc{font-size:13px;color:var(--muted);line-height:1.45}
.deck-meta{display:flex;justify-content:space-between;font-size:12px;color:var(--muted);font-weight:500}
.cat-head{display:flex;align-items:center;gap:10px;margin:28px 0 12px}
.cat-head h2{margin:0}
.cat-line{flex:1;height:1px;background:var(--border)}

/* ---------- Flashcard ---------- */
.study-wrap{max-width:860px;margin:0 auto}
.study-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:16px;flex-wrap:wrap}
.study-head .counter{font-weight:700;font-size:14px;color:var(--muted)}
.flip-scene{perspective:1600px;margin:14px 0}
.flip-card{position:relative;width:100%;min-height:360px;transition:transform .55s cubic-bezier(.4,.2,.2,1);transform-style:preserve-3d;cursor:pointer}
.flip-card.flipped{transform:rotateY(180deg)}
.flip-face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;background:var(--surface);border:1px solid var(--border);border-radius:20px;box-shadow:var(--shadow-lg);padding:36px 40px;display:flex;flex-direction:column}
.flip-face.back{transform:rotateY(180deg)}
.face-label{font-size:11px;font-weight:700;letter-spacing:1.5px;text-transform:uppercase;color:var(--muted);margin-bottom:14px;display:flex;justify-content:space-between;align-items:center}
.face-body{flex:1;display:flex;align-items:center;justify-content:center;text-align:center;font-size:22px;font-weight:600;line-height:1.45;letter-spacing:-.2px}
.flip-face.back .face-body{font-size:18px;font-weight:500;text-align:left;align-items:flex-start;overflow:auto}
.face-foot{display:flex;gap:8px;flex-wrap:wrap;margin-top:16px;align-items:center}
.face-foot .spacer{flex:1}
.pearl{margin-top:14px;padding:12px 14px;border-radius:12px;background:var(--amber-soft);border-left:4px solid var(--amber);font-size:14px}
.pearl b{color:var(--amber)}
.mnemonic{margin-top:10px;padding:12px 14px;border-radius:12px;background:var(--accent-soft);border-left:4px solid var(--accent);font-size:14px}
.mnemonic b{color:var(--accent)}
.rate-row{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin-top:16px}
.rate-btn{padding:14px 10px;border-radius:12px;border:2px solid var(--border);background:var(--surface);font-weight:700;font-size:14px;display:flex;flex-direction:column;gap:2px;align-items:center;transition:all .15s}
.rate-btn small{font-weight:500;color:var(--muted);font-size:11px}
.rate-btn.again:hover{border-color:var(--red);background:var(--red-soft)}
.rate-btn.hard:hover{border-color:var(--amber);background:var(--amber-soft)}
.rate-btn.good:hover{border-color:var(--green);background:var(--green-soft)}
.rate-btn.easy:hover{border-color:var(--primary);background:var(--primary-soft)}
.kbd{display:inline-block;padding:1px 6px;border-radius:5px;border:1px solid var(--border);background:var(--surface-2);font-size:11px;font-family:'JetBrains Mono',monospace;color:var(--muted)}
.study-nav{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-top:14px;flex-wrap:wrap}

/* ---------- Learn / MCQ ---------- */
.q-box{background:var(--surface);border:1px solid var(--border);border-radius:20px;padding:30px 34px;box-shadow:var(--shadow)}
.q-text{font-size:20px;font-weight:600;line-height:1.45;margin-bottom:22px}
.options{display:flex;flex-direction:column;gap:10px}
.opt{text-align:left;padding:14px 16px;border-radius:12px;border:2px solid var(--border);background:var(--surface);font-size:15px;line-height:1.4;transition:all .15s;display:flex;gap:12px;align-items:flex-start}
.opt .key{flex-shrink:0;width:26px;height:26px;border-radius:7px;background:var(--surface-2);display:grid;place-items:center;font-weight:700;font-size:12px;color:var(--muted)}
.opt:hover:not(:disabled){border-color:var(--primary);background:var(--primary-soft)}
.opt.correct{border-color:var(--green);background:var(--green-soft)}
.opt.wrong{border-color:var(--red);background:var(--red-soft)}
.opt:disabled{cursor:default}
.feedback{margin-top:18px;padding:14px 16px;border-radius:12px;font-size:14px}
.feedback.ok{background:var(--green-soft);border-left:4px solid var(--green)}
.feedback.bad{background:var(--red-soft);border-left:4px solid var(--red)}
.write-input{width:100%;min-height:90px;resize:vertical;font-size:16px;margin-bottom:12px}
.answer-reveal{padding:16px;border-radius:12px;background:var(--surface-2);margin-top:10px;font-size:15px}
.self-grade{display:flex;gap:10px;margin-top:14px}

/* ---------- Match game ---------- */
.match-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:12px}
.match-tile{min-height:110px;padding:14px;border-radius:14px;border:2px solid var(--border);background:var(--surface);font-size:13px;line-height:1.35;display:flex;align-items:center;justify-content:center;text-align:center;transition:all .2s;font-weight:500}
.match-tile:hover{border-color:var(--primary);transform:translateY(-2px)}
.match-tile.selected{border-color:var(--primary);background:var(--primary-soft)}
.match-tile.matched{opacity:0;pointer-events:none;transform:scale(.8)}
.match-tile.wrong{border-color:var(--red);background:var(--red-soft);animation:shake .3s}
@keyframes shake{0%,100%{transform:translateX(0)}25%{transform:translateX(-5px)}75%{transform:translateX(5px)}}
.timer{font-family:'JetBrains Mono',monospace;font-size:22px;font-weight:600}

/* ---------- Results ---------- */
.result-hero{text-align:center;padding:36px 20px}
.result-score{font-size:64px;font-weight:800;letter-spacing:-2px;background:linear-gradient(135deg,var(--primary),var(--accent));-webkit-background-clip:text;background-clip:text;color:transparent}
.result-list{display:flex;flex-direction:column;gap:8px;margin-top:20px}
.result-item{display:flex;gap:12px;padding:12px 14px;border-radius:12px;background:var(--surface);border:1px solid var(--border);font-size:14px;align-items:flex-start}
.result-item .mark{font-weight:800;flex-shrink:0;width:22px}
.result-item.ok .mark{color:var(--green)}.result-item.bad .mark{color:var(--red)}

/* ---------- Card list ---------- */
.card-list{display:flex;flex-direction:column;gap:10px}
.card-row{display:grid;grid-template-columns:1fr 1fr auto;gap:16px;padding:16px 18px;background:var(--surface);border:1px solid var(--border);border-radius:12px;font-size:14px;align-items:start}
.card-row .q{font-weight:600}
.card-row .a{color:var(--muted)}
.card-row .acts{display:flex;gap:4px;align-items:center}
.star-btn{background:none;border:none;font-size:18px;color:var(--muted);padding:4px;line-height:1}
.star-btn.on{color:var(--amber)}
.card-row .meta{grid-column:1/-1;display:flex;gap:6px;flex-wrap:wrap;align-items:center}
.mastery-dot{width:10px;height:10px;border-radius:50%;display:inline-block}
.m0{background:var(--border)}.m1{background:var(--red)}.m2{background:var(--amber)}.m3{background:var(--green)}

/* ---------- Search ---------- */
.search-big{width:100%;font-size:17px;padding:16px 18px;border-radius:14px}
mark{background:var(--amber-soft);color:inherit;padding:0 2px;border-radius:3px}

/* ---------- Tables / stats ---------- */
table{width:100%;border-collapse:collapse;font-size:14px}
th,td{text-align:left;padding:10px 12px;border-bottom:1px solid var(--border)}
th{font-size:12px;text-transform:uppercase;letter-spacing:.8px;color:var(--muted);font-weight:700}
.bar-chart{display:flex;align-items:flex-end;gap:6px;height:140px;padding-top:10px}
.bar{flex:1;background:var(--primary);border-radius:6px 6px 0 0;min-height:3px;position:relative;opacity:.85;transition:height .4s}
.bar:hover{opacity:1}
.bar-lbl{position:absolute;top:100%;left:50%;transform:translateX(-50%);font-size:10px;color:var(--muted);margin-top:4px;white-space:nowrap}
.bar-val{position:absolute;bottom:100%;left:50%;transform:translateX(-50%);font-size:11px;font-weight:700;margin-bottom:2px}
.heat{display:grid;grid-template-columns:repeat(auto-fill,minmax(14px,1fr));gap:3px}
.heat div{aspect-ratio:1;border-radius:3px;background:var(--surface-2)}
.heat .h1{background:#bfdbfe}.heat .h2{background:#60a5fa}.heat .h3{background:#2563eb}.heat .h4{background:#1e3a8a}
[data-theme="dark"] .heat .h1{background:#1e3a8a}[data-theme="dark"] .heat .h2{background:#1d4ed8}[data-theme="dark"] .heat .h3{background:#3b82f6}[data-theme="dark"] .heat .h4{background:#93c5fd}

/* ---------- Modal / toast ---------- */
.modal-bg{position:fixed;inset:0;background:rgba(2,6,23,.55);backdrop-filter:blur(3px);display:grid;place-items:center;z-index:100;animation:fade .2s}
.modal{background:var(--surface);border-radius:18px;padding:26px;max-width:560px;width:calc(100% - 32px);max-height:90vh;overflow:auto;box-shadow:var(--shadow-lg)}
.modal h2{margin-bottom:16px}
.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:20px}
.form-row{display:flex;flex-direction:column;gap:6px;margin-bottom:14px}
.form-row label{font-size:13px;font-weight:600;color:var(--muted)}
#toast-root{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);display:flex;flex-direction:column;gap:8px;z-index:200}
.toast{background:var(--text);color:var(--bg);padding:12px 18px;border-radius:12px;font-weight:600;font-size:14px;box-shadow:var(--shadow-lg);animation:fade .2s}
.shortcut-grid{display:grid;grid-template-columns:auto 1fr;gap:8px 16px;font-size:14px}

/* ---------- Setup panel ---------- */
.mode-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(170px,1fr));gap:12px}
.mode-tile{padding:18px 16px;border-radius:14px;border:2px solid var(--border);background:var(--surface);text-align:left;transition:all .15s}
.mode-tile:hover{border-color:var(--primary);transform:translateY(-2px);box-shadow:var(--shadow)}
.mode-tile .ico{font-size:24px;margin-bottom:8px}
.mode-tile .nm{font-weight:700;font-size:14px}
.mode-tile .ds{font-size:12px;color:var(--muted);margin-top:2px}
.toggle-row{display:flex;align-items:center;justify-content:space-between;padding:12px 0;border-bottom:1px solid var(--border);gap:12px}
.toggle-row:last-child{border-bottom:none}
.switch{position:relative;width:44px;height:24px;flex-shrink:0}
.switch input{opacity:0;width:0;height:0}
.switch span{position:absolute;inset:0;background:var(--border);border-radius:999px;transition:.2s;cursor:pointer}
.switch span:before{content:"";position:absolute;width:18px;height:18px;left:3px;top:3px;background:#fff;border-radius:50%;transition:.2s}
.switch input:checked + span{background:var(--primary)}
.switch input:checked + span:before{transform:translateX(20px)}

.empty{text-align:center;padding:50px 20px;color:var(--muted)}
.empty .big{font-size:42px;margin-bottom:10px}

@media (max-width:900px){
  #sidebar{transform:translateX(-100%)}
  #sidebar.open{transform:none;box-shadow:var(--shadow-lg)}
  #main-wrap{margin-left:0}
  #menu-btn{display:grid}
  main#view{padding:18px}
  .flip-face{padding:24px 20px}
  .face-body{font-size:18px}
  .card-row{grid-template-columns:1fr}
  .rate-row{grid-template-columns:repeat(2,1fr)}
  #topbar{padding:12px 16px}
}

/* ================= v2: UI polish, audio bar, mobile ================= */
.deck-card{--hue:220}
.deck-card .deck-icon{background:hsl(var(--hue) 85% 93%);box-shadow:inset 0 0 0 1px hsl(var(--hue) 60% 85%)}
[data-theme="dark"] .deck-card .deck-icon{background:hsl(var(--hue) 45% 22%);box-shadow:inset 0 0 0 1px hsl(var(--hue) 40% 32%)}
.deck-card:hover .deck-icon{transform:scale(1.06)}
.deck-icon{transition:transform .15s}
.chip-scroll{flex-wrap:nowrap;overflow-x:auto;padding-bottom:6px;margin-bottom:6px;scrollbar-width:none;-webkit-overflow-scrolling:touch}
.chip-scroll::-webkit-scrollbar{display:none}
.chip-scroll .chip{flex-shrink:0}
.flip-face{background:linear-gradient(180deg,var(--surface) 0%,var(--surface) 100%)}
.flip-face.front{border-top:4px solid var(--primary)}
.flip-face.back{border-top:4px solid var(--accent)}
.flip-hint{font-size:12px;color:var(--muted)}
.tool-btn{min-width:38px;justify-content:center}
[data-speak].speaking{background:var(--green-soft);border-color:var(--green);color:var(--green)}
.row-speak{width:32px;height:32px;font-size:13px}
.row-speak.speaking{background:var(--green-soft);border-color:var(--green)}
.rate-btn:active,.opt:active,.match-tile:active,.mode-tile:active{transform:scale(.97)}
.card.clickable:active{transform:scale(.99)}
.result-hero{border-top:4px solid var(--primary)}
.mode-tile .ico{font-size:26px}
.nav-link .nav-ico{font-size:16px}
main#view{padding-bottom:60px}

/* audio bar */
#speak-bar{position:fixed;bottom:22px;right:22px;z-index:150;display:flex;align-items:center;gap:12px;background:var(--surface);border:1px solid var(--border);box-shadow:var(--shadow-lg);padding:8px 8px 8px 16px;border-radius:999px;font-weight:600;font-size:14px;animation:fade .2s}
.speak-dot{width:10px;height:10px;border-radius:50%;background:var(--green);animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.25}}
#speak-bar .btn{border-color:var(--red);color:var(--red)}
#speak-bar .btn:hover{background:var(--red-soft)}

/* mobile chrome */
#bottom-nav{display:none}
#sidebar-overlay{display:none;position:fixed;inset:0;background:rgba(2,6,23,.45);backdrop-filter:blur(2px);z-index:39}
#sidebar-overlay.show{display:block}
.card:has(> table){overflow-x:auto}

@media (max-width:900px){
  #bottom-nav{display:flex;position:fixed;bottom:0;left:0;right:0;background:var(--surface);border-top:1px solid var(--border);z-index:38;padding:6px 4px calc(6px + env(safe-area-inset-bottom,0px))}
  #bottom-nav a{flex:1;display:flex;flex-direction:column;align-items:center;gap:2px;font-size:11px;font-weight:600;color:var(--muted);padding:4px 0;border-radius:10px;-webkit-tap-highlight-color:transparent}
  #bottom-nav a span{font-size:21px;line-height:1}
  #bottom-nav a.active{color:var(--primary)}
  #sidebar{width:min(84vw,300px);z-index:40;padding-top:env(safe-area-inset-top,0px)}
  #topbar{padding:10px 14px;gap:8px}
  .topbar-search input{font-size:16px;padding:9px 12px}
  .icon-btn{width:36px;height:36px}
  main#view{padding:16px 16px calc(96px + env(safe-area-inset-bottom,0px))}
  h1{font-size:22px}h2{font-size:18px}.sub{font-size:14px;margin-bottom:16px}
  .page-head{flex-direction:column;align-items:stretch;gap:10px;margin-bottom:14px}
  .page-head .row{width:100%}
  .page-head .row .btn,.page-head .row input,.page-head .row select{flex:1;justify-content:center;min-width:0}
  .btn.lg{padding:12px 16px;font-size:15px}
  .stat-tiles{grid-template-columns:repeat(2,1fr);gap:10px;margin-bottom:18px}
  .tile{padding:14px}.tile-val{font-size:24px}.tile-lbl{font-size:12px}
  .grid-2,.grid-3,.grid-4{grid-template-columns:1fr;gap:12px}
  .card{padding:16px;border-radius:12px}
  .mode-grid{grid-template-columns:repeat(2,1fr);gap:10px}
  .mode-tile{padding:14px 12px}.mode-tile .ico{font-size:22px;margin-bottom:6px}.mode-tile .nm{font-size:13px}.mode-tile .ds{font-size:11px}
  .cat-head{margin:20px 0 10px}
  .deck-desc{display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
  /* study */
  .study-head{gap:8px;margin-bottom:10px}
  .study-head .row{gap:6px}
  .flip-scene{margin:8px 0}
  .flip-card{min-height:min(62vh,420px)}
  .flip-face{padding:18px 16px;border-radius:16px}
  .face-label{font-size:10px;margin-bottom:10px}
  .face-body{font-size:17px}
  .flip-face.back .face-body{font-size:15px}
  .pearl,.mnemonic{font-size:13px;padding:10px 12px;margin-top:10px}
  .rate-row{grid-template-columns:repeat(4,1fr);gap:6px;margin-top:12px}
  .rate-btn{padding:10px 4px;font-size:13px;border-radius:10px}
  .rate-btn small{font-size:10px}
  .rate-btn small .kbd{display:none}
  .study-nav{gap:8px}
  .study-nav .btn{flex:1;justify-content:center;padding:12px 8px}
  .q-box{padding:18px 16px;border-radius:16px}
  .q-text{font-size:17px;margin-bottom:14px}
  .opt{padding:12px;font-size:14px;gap:10px}
  .opt .key{display:none}
  .feedback{font-size:13px;padding:12px}
  .self-grade{flex-direction:column}
  .match-grid{grid-template-columns:repeat(2,1fr);gap:8px}
  .match-tile{min-height:88px;font-size:12px;padding:10px;border-radius:12px}
  .result-hero{padding:24px 14px}.result-score{font-size:48px}
  .result-item{padding:10px 12px;font-size:13px}
  /* lists & tables */
  .card-row{grid-template-columns:1fr;gap:8px;padding:14px}
  .card-row .acts{order:-1;justify-content:flex-end}
  table{font-size:13px;min-width:420px}th,td{padding:8px 6px}
  .bar-chart{height:110px}
  .heat{grid-template-columns:repeat(auto-fill,minmax(10px,1fr))}
  .modal{padding:18px;border-radius:14px;max-height:88vh}
  .modal-actions .btn{flex:1;justify-content:center}
  #speak-bar{bottom:calc(76px + env(safe-area-inset-bottom,0px));right:12px;left:12px;justify-content:space-between;border-radius:14px}
  .search-big{font-size:16px;padding:13px 14px}
  .toggle-row{flex-wrap:wrap}
  #toast-root{bottom:calc(80px + env(safe-area-inset-bottom,0px));width:calc(100% - 32px)}
  .toast{text-align:center}
  .refs-note{display:none}
}
@media (max-width:420px){
  .rate-row{grid-template-columns:repeat(2,1fr)}
  .mode-grid{grid-template-columns:1fr 1fr}
  .stat-tiles{grid-template-columns:repeat(2,1fr)}
  .tile-val{font-size:22px}
}
@media (hover:none){
  .card.clickable:hover{transform:none}
}
/* v2.1 small-screen hardening */
.face-label{flex-wrap:wrap;gap:6px}
.face-label > span:not(.chip){flex-shrink:0}
@media (max-width:900px){
  .page-head .row .btn{flex:1 1 140px;white-space:normal;text-align:center}
  .btn.lg{white-space:normal}
  .flip-card{min-height:min(52vh,380px)}
  .row > input,.row > select{max-width:100%}
}
/* buttons must follow the theme text color (fixes dark-mode mode/rate/option/match tiles) */
.mode-tile,.rate-btn,.opt,.match-tile{color:var(--text)}