:root{--bg:#08090b;--card:#161719;--el:#212225;--line:#2a2b2e;--ink:#fff;--ink-soft:#b0b4ba;--muted:#8a8f98;--sky:#3c9bf7;--sky-dark:#208aef;--mint:#4ade80;--coral:#f87171;--sun:#fbbf24;--radius:18px;color:var(--ink);font-family:Roboto Condensed,Arial Narrow,system-ui,sans-serif}*{box-sizing:border-box}body{background:radial-gradient(90% 40% at 8% -4%, #3c9bf738 0%, transparent 62%), radial-gradient(70% 34% at 100% 4%, #4ade8024 0%, transparent 60%), radial-gradient(120% 50% at 50% 106%, #fbbf241a 0%, transparent 58%), var(--bg);min-height:100vh;color:var(--ink);-webkit-font-smoothing:antialiased;-webkit-tap-highlight-color:transparent;margin:0}.app{max-width:780px;margin:0 auto;padding:20px 18px 56px}.screen{animation:.28s ease-out rise}@keyframes rise{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:none}}button{font:inherit;cursor:pointer;color:inherit;background:0 0;border:none}.big-btn{background:var(--sky);color:#08090b;letter-spacing:.02em;text-transform:uppercase;border-radius:16px;width:100%;padding:18px;font-size:1.3rem;font-weight:900;transition:transform 80ms,filter .15s;box-shadow:0 10px 28px #3c9bf747}.big-btn:active{transform:translateY(2px)}.big-btn:hover{filter:brightness(1.06)}.big-btn.is-secondary{background:var(--card);border:1px solid var(--line);color:var(--ink);box-shadow:none}.ghost-btn{border:1px solid var(--line);background:var(--card);color:var(--muted);white-space:nowrap;border-radius:999px;padding:9px 14px;font-size:.9rem;font-weight:700}.ghost-btn:hover{color:var(--ink)}.link-btn{color:var(--sky);border-bottom:1px solid #3c9bf759;padding:2px 0;font-size:.9rem;font-weight:700}.mute-btn{z-index:5;border:1px solid var(--line);background:var(--card);height:34px;color:var(--sky);letter-spacing:.08em;text-transform:uppercase;border-radius:999px;padding:0 14px;font-size:.78rem;font-weight:700;line-height:1;position:fixed;top:14px;right:14px}.hero{padding:6px 0 22px}.hero-badge{background:var(--sky);color:#08090b;border-radius:13px;place-items:center;width:46px;height:46px;margin:0 0 14px;font-size:1.5rem;display:grid}.hero h1{letter-spacing:-.01em;text-transform:uppercase;color:var(--ink);margin:0;font-size:clamp(2.4rem,10vw,3.5rem);font-weight:900;line-height:.94}.hero-sub{color:var(--ink-soft);max-width:46ch;margin:12px 0 0;font-size:1.05rem}.learn-btn{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:999px;margin-top:16px;padding:11px 18px;font-size:.95rem;font-weight:700}.learn-btn:hover{border-color:var(--sky);color:var(--sky)}.record-strip{color:var(--muted);letter-spacing:.08em;text-transform:uppercase;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px;margin-bottom:22px;font-size:.82rem;font-weight:700;display:grid}.record-strip span{background:var(--card);border:1px solid var(--line);border-radius:14px;flex-direction:column;gap:2px;padding:12px 14px;display:flex}.record-strip strong{color:var(--ink);letter-spacing:0;text-transform:none;font-variant-numeric:tabular-nums;font-size:1.6rem;font-weight:900}.panel{background:var(--card);border:1px solid var(--line);border-radius:20px;margin-bottom:14px;padding:18px}.panel h2{align-items:center;gap:10px;margin:0 0 12px;font-size:1.2rem;font-weight:800;display:flex}.step{background:var(--el);width:26px;height:26px;color:var(--muted);border-radius:8px;place-items:center;font-size:.9rem;font-weight:800;display:grid}.panel-hint{color:var(--muted);margin:0 0 12px;font-size:.9rem}.mode-cards{grid-template-columns:1fr;gap:10px;display:grid}@media (width>=480px){.mode-cards{grid-template-columns:1fr 1fr}}.mode-cards.is-operations{grid-template-columns:repeat(auto-fit,minmax(168px,1fr))}.mode-head{align-items:center;gap:9px;display:flex}.op-symbol{background:var(--el);border:1px solid var(--line);width:28px;height:28px;color:var(--ink-soft);border-radius:8px;flex:none;place-items:center;font-size:.95rem;font-weight:800;line-height:1;display:grid}.mode-card.is-on .op-symbol{background:var(--sky);border-color:var(--sky);color:#08090b}.mode-card{text-align:left;background:var(--el);border:1px solid var(--line);border-radius:16px;flex-direction:column;gap:5px;padding:15px;transition:border-color .14s,background .14s,box-shadow .14s;display:flex}.mode-title{font-size:1.2rem;font-weight:800}.mode-blurb{color:var(--muted);font-size:.88rem;line-height:1.3}.mode-card.is-on{background:color-mix(in srgb, var(--sky) 16%, var(--card));border-color:var(--sky);box-shadow:0 0 0 3px #3c9bf738}.sub-setting{border-top:1px solid var(--line);margin-top:16px;padding-top:16px}.sub-setting .panel-hint{margin-bottom:10px}.panel-note{background:var(--el);color:var(--ink-soft);border-radius:12px;margin:16px 0 0;padding:12px 14px;font-size:.92rem;line-height:1.4}.chip-row{grid-template-columns:repeat(4,1fr);gap:8px;display:grid}.chip{background:var(--el);border:1px solid var(--line);border-radius:14px;flex-direction:column;align-items:center;gap:2px;padding:11px 6px;transition:border-color .14s,background .14s;display:flex}.chip-main{font-variant-numeric:tabular-nums;font-size:1.35rem;font-weight:900}.chip-hint{letter-spacing:.06em;text-transform:uppercase;color:var(--muted);font-size:.72rem;font-weight:700}.chip.is-on{background:color-mix(in srgb, var(--sky) 18%, var(--card));border-color:var(--sky)}.table-grid{flex-wrap:wrap;gap:8px;display:flex}.table-key{background:var(--el);border:1px solid var(--line);font-variant-numeric:tabular-nums;min-width:44px;height:44px;color:var(--ink-soft);border-radius:12px;place-items:center;padding:0 10px;font-size:1.05rem;font-weight:800;transition:background .12s,color .12s,border-color .12s;display:grid}.table-grid.is-squares .table-key{min-width:52px}.table-key.is-on{background:var(--sky);border-color:var(--sky);color:#08090b}.mini-row{flex-wrap:wrap;gap:16px;margin-top:14px;display:flex}.hud{justify-content:space-between;align-items:center;gap:12px;margin-bottom:14px;padding-right:96px;display:flex}.hud-stats{gap:8px;display:flex}.hud .stat{background:var(--card);border:1px solid var(--line);text-align:center;border-radius:12px;min-width:76px;padding:6px 14px}.stat-label{text-transform:uppercase;letter-spacing:.12em;color:var(--muted);font-size:.68rem;font-weight:700;display:block}.stat-value{font-variant-numeric:tabular-nums;font-size:1.25rem;font-weight:900;display:block}@media (width<=420px){.hud .stat{min-width:64px;padding:5px 10px}.hud .stat-value{font-size:1.05rem}.ghost-btn{padding:8px 10px;font-size:.82rem}}.progress{background:var(--el);border-radius:999px;height:10px;margin-bottom:26px;position:relative}.progress-fill{background:var(--sky);border-radius:999px;height:100%;transition:width .3s}.progress-text{letter-spacing:.08em;text-transform:uppercase;color:var(--muted);font-size:.78rem;font-weight:700;position:absolute;top:14px;left:0}.timer{width:104px;height:104px;margin:0 auto 6px;position:relative}.timer-ring{width:100%;height:100%;transform:rotate(-90deg)}.ring-track{fill:none;stroke:var(--el);stroke-width:12px}.ring-fill{fill:none;stroke:var(--sky);stroke-width:12px;stroke-linecap:round;transition:stroke-dashoffset .12s linear,stroke .3s}.timer.is-urgent .ring-fill{stroke:var(--coral)}.timer.is-urgent .timer-number{color:var(--coral);animation:.6s ease-in-out infinite pulse}@keyframes pulse{50%{opacity:.5}}.timer-label{text-align:center;place-content:center;display:grid;position:absolute;inset:0}.timer-number{font-variant-numeric:tabular-nums;font-size:1.7rem;font-weight:900;line-height:1;display:block}.timer-unit{letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-top:3px;font-size:.62rem;font-weight:700;display:block}.question{background:var(--card);border:1px solid var(--line);font-variant-numeric:tabular-nums;border-radius:24px;flex-wrap:wrap;justify-content:center;align-items:center;gap:14px;margin-bottom:14px;padding:8px 18px 26px;font-size:clamp(2.6rem,12vw,4rem);font-weight:900;line-height:1;display:flex}.question .times,.question .equals{color:var(--muted);font-size:.62em;font-weight:700}.question .blank{color:var(--muted);min-width:1.2ch}.question .blank.is-good{color:var(--mint)}.question .blank.is-bad{color:var(--coral)}.timer,.stopwatch{z-index:1;position:relative}.stopwatch{place-items:center;gap:4px;margin:0 auto 6px;padding:10px;display:grid}.stopwatch-time{font-variant-numeric:tabular-nums;color:var(--sun);font-size:2.3rem;font-weight:900;line-height:1}.stopwatch-label{text-transform:uppercase;letter-spacing:.14em;color:var(--muted);font-size:.68rem;font-weight:700}.answer-form{grid-template-columns:1fr auto;align-items:stretch;gap:10px;display:grid}.answer-input{border:1px solid var(--line);background:var(--card);width:100%;font:inherit;font-variant-numeric:tabular-nums;text-align:center;color:var(--ink);border-radius:16px;outline:none;padding:16px 18px;font-size:2.1rem;font-weight:900;transition:border-color .15s}.answer-input::placeholder{color:#4a4e55}.answer-input:focus:not(.is-good):not(.is-bad){border-color:var(--sky);box-shadow:0 0 0 3px #3c9bf738}.answer-input.is-good{border-color:var(--mint);color:var(--mint)}.answer-input.is-bad{border-color:var(--coral);color:var(--coral);animation:.35s shake}.check-btn{background:var(--sky);color:#08090b;text-transform:uppercase;border-radius:16px;padding:0 26px;font-size:1.15rem;font-weight:900}.check-btn:disabled{background:var(--el);color:var(--muted)}.options{grid-template-columns:repeat(2,1fr);gap:10px;display:grid}.option{background:var(--card);border:1px solid var(--line);font-variant-numeric:tabular-nums;border-radius:18px;place-items:center;min-height:84px;padding:20px 10px;font-size:2.1rem;font-weight:900;transition:transform 80ms,border-color .14s,background .14s,opacity .2s;display:grid;position:relative}.option:not(:disabled):hover{border-color:var(--sky)}.option:not(:disabled):active{transform:translateY(2px)}.option-key{letter-spacing:.06em;color:var(--muted);font-size:.7rem;font-weight:800;position:absolute;top:10px;left:12px}.option.is-correct{background:color-mix(in srgb, var(--mint) 18%, var(--card));border-color:var(--mint);color:var(--mint);animation:.3s pop}.option.is-wrong{background:color-mix(in srgb, var(--coral) 16%, var(--card));border-color:var(--coral);color:var(--coral);animation:.35s shake}.option.is-dim{opacity:.35}@keyframes pop{40%{transform:scale(1.04)}}@keyframes shake{25%{transform:translate(-7px)}75%{transform:translate(7px)}}.flash{opacity:0;place-items:center;min-height:52px;margin-top:14px;font-size:1.2rem;font-weight:800;transition:opacity .15s;display:grid}.flash.is-shown{opacity:1}.flash-good,.flash-bad{border-radius:999px;padding:10px 20px;animation:.22s ease-out pop}.flash-good{color:var(--mint);background:#4ade8024;border:1px solid #4ade8066}.flash-bad{color:var(--coral);background:#f8717124;border:1px solid #f8717166}.results{text-align:center}.stars{letter-spacing:8px;margin-top:10px;font-size:2.5rem}.star{color:var(--line)}.star.is-lit{color:var(--sun);text-shadow:0 0 22px #fbbf2473}.results-score{font-variant-numeric:tabular-nums;margin:14px 0 0;font-size:4.4rem;font-weight:900;line-height:1}.results-score span{color:var(--muted);font-size:2.1rem}.results-praise{color:var(--mint);margin:8px 0 18px;font-size:1.2rem;font-weight:700}.badge-row{flex-wrap:wrap;justify-content:center;gap:8px;margin-bottom:18px;display:flex}.badge{color:var(--sun);letter-spacing:.04em;text-transform:uppercase;background:#fbbf2424;border:1px solid #fbbf2466;border-radius:999px;padding:7px 14px;font-size:.85rem;font-weight:800}.stat-grid{grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px;margin-bottom:16px;display:grid}.stat-card{background:var(--card);border:1px solid var(--line);text-align:left;border-radius:16px;padding:14px 16px}.stat-card .stat-value{margin-top:2px;font-size:1.8rem}.stat-card.is-headline{background:color-mix(in srgb, var(--sky) 14%, var(--card));border-color:var(--sky)}.stat-card.is-headline .stat-value{color:var(--sun)}.results-note{background:var(--el);color:var(--ink-soft);text-align:left;border-radius:12px;margin:0 0 16px;padding:12px 14px;font-size:.92rem;line-height:1.4}.practice{text-align:left}.practice h2{margin-bottom:12px;font-size:1.2rem}.practice-list{flex-wrap:wrap;gap:8px;margin:0;padding:0;list-style:none;display:flex}.practice-list li{background:var(--el);border:1px solid var(--line);font-variant-numeric:tabular-nums;border-radius:12px;align-items:baseline;gap:8px;padding:9px 14px;font-size:1.1rem;font-weight:800;display:inline-flex}.practice-answer{color:var(--coral);font-weight:900}.button-row{gap:10px;margin-top:8px;display:grid}@media (width>=520px){.button-row{grid-template-columns:1fr 1fr}}@media (prefers-reduced-motion:reduce){*,:before,:after{transition:none!important;animation:none!important}}.learn-head{align-items:center;gap:12px;margin-bottom:16px;padding-right:96px;display:flex}.learn-title{text-transform:uppercase;letter-spacing:-.01em;margin:0;font-size:1.9rem;font-weight:900}.tabs{background:var(--card);border:1px solid var(--line);border-radius:14px;grid-template-columns:repeat(auto-fit,minmax(92px,1fr));gap:6px;margin-bottom:14px;padding:5px;display:grid}.tab{text-align:center;color:var(--muted);border-radius:10px;padding:11px 6px;font-size:.95rem;font-weight:800;transition:background .14s,color .14s}.tab.is-on{background:var(--sky);color:#08090b}.learn .panel h2{margin-bottom:10px}.fact-list{grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:8px;margin:0;padding:0;list-style:none;display:grid}.fact-row{background:var(--el);border:1px solid var(--line);font-variant-numeric:tabular-nums;border-radius:12px;justify-content:space-between;align-items:center;gap:10px;width:100%;padding:11px 14px;font-size:1.05rem;font-weight:700;transition:border-color .12s,background .12s;display:flex}.fact-left{color:var(--ink-soft)}.fact-equals{display:none}.fact-answer{color:var(--ink);font-size:1.25rem;font-weight:900}.fact-row.is-on{background:color-mix(in srgb, var(--sky) 14%, var(--card));border-color:var(--sky)}.fact-row.is-on .fact-answer{color:var(--sky)}.array-model{justify-content:start;gap:6px;padding:4px 0;display:grid}.dot-row{gap:6px;display:flex}.visual-caption{color:var(--ink-soft);margin:0 0 12px;font-size:.95rem}.visual-caption strong{color:var(--ink)}.dot-flow{flex-wrap:wrap;gap:6px;max-width:420px;padding:4px 0;display:flex}.dot.is-added{background:var(--mint)}.dot.is-gone{border:2px solid var(--muted);background:0 0;position:relative}.dot.is-gone:after{content:"";border-top:2px solid var(--coral);position:absolute;inset:45% -2px;transform:rotate(-45deg)}.dot{background:var(--sky);border-radius:5px;flex:none}.array-empty{color:var(--muted);padding:10px 0}.array-empty p{margin:0}.array-empty strong{color:var(--ink);font-size:1.15rem}.chart-toggle{padding:0}.chart-scroll{margin-top:12px;overflow-x:auto}.chart{border-collapse:collapse;font-variant-numeric:tabular-nums;width:100%;min-width:520px;font-size:.85rem}.chart th,.chart td{border:1px solid var(--line);text-align:center;color:var(--muted);padding:6px 4px}.chart th{background:var(--el);color:var(--ink);font-weight:800}.chart th.is-axis{background:var(--sky);color:#08090b}.chart td.is-lit{background:color-mix(in srgb, var(--sky) 14%, var(--card));color:var(--ink);font-weight:700}.chart td.is-diagonal{outline:1px solid var(--sun);outline-offset:-1px}.chart-key{color:var(--muted);margin:10px 0 0;font-size:.82rem}.square-grid{grid-template-columns:repeat(auto-fit,minmax(94px,1fr));gap:8px;margin:0;padding:0;list-style:none;display:grid}.square-card{background:var(--el);border:1px solid var(--line);font-variant-numeric:tabular-nums;border-radius:14px;gap:2px;width:100%;padding:11px 13px;transition:border-color .12s,background .12s;display:grid}.square-label{color:var(--muted);font-size:.9rem;font-weight:800}.square-value{font-size:1.4rem;font-weight:900}.square-card.is-on{background:color-mix(in srgb, var(--sky) 14%, var(--card));border-color:var(--sky)}