:root{font-family:ui-sans-serif,system-ui,-apple-system,"Segoe UI","Malgun Gothic",sans-serif;color:#202536;background:#f7f8fc;font-size:16px;line-height:1.65;font-synthesis:none;--primary:#4663e2;--muted:#626a7d;--line:#e0e4ee}
*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit}button,a,input,select,summary{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}a{color:inherit;text-decoration:none}button{cursor:pointer}button:disabled{cursor:default;opacity:.52}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #354db7;outline-offset:4px}h1,h2,p{margin:0}h1{font-size:clamp(1.6rem,5vw,2rem);line-height:1.35;letter-spacing:-.035em}h2{font-size:1.22rem;line-height:1.45;letter-spacing:-.025em}p{overflow-wrap:anywhere}small{display:block;color:var(--muted);font-size:.82rem;line-height:1.6}svg{width:24px;height:24px;flex:none}.brand{max-width:680px;margin:auto;padding:24px 24px 12px;display:flex;align-items:center;justify-content:space-between;font-size:.88rem;font-weight:700}.brand a{min-height:48px;display:flex;align-items:center;gap:6px}.brand span{color:var(--muted);font-weight:400}.brand #connection{font-size:.75rem}
main{max-width:648px;margin:0 auto;padding:22px 24px calc(128px + env(safe-area-inset-bottom));display:flex;flex-direction:column;gap:24px;min-height:75vh;outline:none}main>section{display:flex;flex-direction:column;gap:14px}main[aria-busy=true]{cursor:progress}.heading{display:flex;flex-direction:column;gap:10px}.heading p{color:var(--muted)}.today{background:white;border-radius:18px;padding:26px;gap:16px!important;box-shadow:0 4px 20px #20253605}.today h2{font-size:1.75rem}.eyebrow{color:#354db7;font-size:.88rem;font-weight:650}.meta{color:var(--muted);font-size:.86rem}.primary,.secondary,.choice,.text-button{min-height:52px;border-radius:12px;padding:12px 18px;border:1px solid transparent;display:inline-flex;align-items:center;justify-content:center;gap:8px;text-align:center;line-height:1.5;overflow-wrap:anywhere}.primary{color:white;background:var(--primary);font-weight:650;box-shadow:0 3px 0 #344eba}.secondary,.choice{color:#202536;background:#fff;border-color:#d4dae7}.text-button{color:#354db7;background:transparent;padding-inline:8px}.primary:hover:not(:disabled){background:#3c57ce}.secondary:hover:not(:disabled),.choice:hover:not(:disabled){background:#edf0ff}.primary:active{transform:translateY(1px)}.choice[aria-pressed=true]{border-color:var(--primary);background:#eaf0ff;color:#354db7;box-shadow:inset 0 0 0 1px var(--primary)}.choices{display:flex;gap:10px;flex-wrap:wrap}.choices>*{flex:1;min-width:80px}.between{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap}.between h2{flex:1}.destination{display:flex;align-items:center;gap:16px;padding:16px 0;border-bottom:1px solid var(--line);min-height:80px}.destination>svg{color:#354db7}.destination>span:nth-child(2){flex:1}.destination strong,.lesson-row strong{font-size:1.05rem;font-weight:600;display:block}.destination small,.lesson-row small{margin-top:4px}.destination:hover strong,.lesson-row:hover strong{color:var(--primary)}progress{width:100%;height:8px;border:0;border-radius:9px;overflow:hidden;background:#e4e8f3}progress::-webkit-progress-bar{background:#e4e8f3}progress::-webkit-progress-value{background:var(--primary)}progress::-moz-progress-bar{background:var(--primary)}.lesson-row{display:flex;align-items:center;gap:16px;padding:18px 0;border-bottom:1px solid var(--line)}.lesson-row>span:nth-child(2){flex:1}.node{background:#e9edff;color:#354db7;border-radius:50%;width:36px;min-height:36px;display:inline-flex;align-items:center;justify-content:center;flex:none}.stage-list{padding:0;list-style:none;margin:0;display:flex;flex-direction:column;gap:22px}.stage-list li{display:flex;align-items:center;gap:18px}.step-track{display:flex;gap:8px}.step-track span{flex:1;border-top:4px solid #e2e6f1;padding-top:8px;font-size:.78rem;color:var(--muted);text-align:center}.step-track .filled{border-color:var(--primary)}.step-track [aria-current]{color:#354db7;font-weight:700}.transcript{white-space:pre-line;background:white;border-radius:16px;padding:24px;font-size:1.1rem;line-height:1.95}video{max-width:100%;max-height:55vh;background:#202536;border-radius:12px;align-self:center}details{border-top:1px solid var(--line);padding-top:8px}summary{cursor:pointer;min-height:48px;padding:10px 0;color:#354db7}details p{padding:12px 0}details .primary{width:100%;margin-top:18px}.study-card{min-height:280px;background:white;border:1px solid #e0e4ee;border-radius:18px;box-shadow:0 5px 0 #e5e9f3,0 12px 0 -3px #eef0f7;display:flex;align-items:center;justify-content:center;text-align:center;padding:28px;touch-action:pan-y;user-select:none;transition:transform 80ms linear}.study-card p{font-size:1.6rem;line-height:1.7;white-space:pre-line;font-weight:600;letter-spacing:-.025em}.center{text-align:center}.problem{font-size:1.5rem;padding:16px 0}.option-list{display:flex;flex-direction:column;gap:10px}.option-list .choice{justify-content:flex-start;text-align:left;padding:16px}.feedback{padding:20px;background:#eaf0ff;border-radius:12px;display:flex;flex-direction:column;gap:14px}.feedback.correct{background:#eaf6ef}.feedback h2{font-size:1.1rem}.input-label{display:flex;flex-direction:column;gap:8px}input:not([type=checkbox]):not([type=range]),select{width:100%;min-height:52px;border:1px solid #b7c0d4;border-radius:10px;padding:10px 14px;color:#202536;background:white;min-width:0}input:disabled{background:#f0f2f8}input[type=range]{width:100%;accent-color:var(--primary);height:48px;min-width:40px}input[type=checkbox]{width:24px;height:24px;accent-color:var(--primary);flex:none}.keypad{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:8px}.keypad button{min-height:48px}.results{display:flex;flex-wrap:wrap;gap:24px;margin:0;padding:24px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.results>div{flex:1}.results dt{color:var(--muted);font-size:.88rem}.results dd{margin:8px 0 0;font-size:1.6rem;font-weight:700}.completion-mark{width:72px;height:72px;border-radius:50%;background:#eaf0ff;color:var(--primary);display:grid;place-items:center;font-size:2.2rem}.summary{font-size:1.2rem}.classify{display:flex;flex-direction:column;gap:20px}.classify fieldset{border:0;padding:0;margin:0}.classify legend{font-size:1.4rem;font-weight:700;padding-bottom:8px}.classify .choice{padding:10px 8px}.plot{margin:0;display:flex;flex-direction:column;gap:8px}.plot canvas{width:100%;height:auto;aspect-ratio:1;background:white;border:1px solid var(--line);border-radius:12px}.plot.wide canvas{aspect-ratio:10/7}.plot figcaption{font-size:.82rem;color:var(--muted)}.formula{font-size:1.4rem;text-align:center;font-variant-numeric:tabular-nums}.slider-row{display:flex;align-items:center;gap:14px}.slider-control label{font-weight:650}.slider-row button{min-width:48px;padding:10px}.fill-equation{display:flex;align-items:center;gap:10px;font-size:1.4rem}.fill-equation label{flex:1;min-width:0}.fill-equation>span{flex:none}.symbols{display:flex;flex-wrap:wrap;gap:8px}.symbols button{min-width:48px;padding:8px 12px}.setting{display:flex;align-items:center;gap:16px;justify-content:space-between;min-height:76px;padding:12px 0;border-bottom:1px solid var(--line)}.setting strong{font-weight:500}.setting small{margin-top:4px}nav{position:fixed;bottom:0;left:50%;transform:translateX(-50%);width:min(100%,680px);padding:8px 8px calc(8px + env(safe-area-inset-bottom));display:flex;background:#fffffffa;border-top:1px solid var(--line);z-index:5}nav a{flex:1;min-width:0;padding:8px 2px;display:flex;flex-direction:column;gap:5px;align-items:center;color:var(--muted);font-size:.75rem;line-height:1.4}nav a[aria-current]{color:#354db7;font-weight:700}nav a[aria-current]::after{content:"";height:3px;width:24px;background:var(--primary);border-radius:5px}nav[hidden],[hidden]{display:none!important}#notice{position:sticky;top:0;z-index:10;max-width:680px;margin:auto;padding:16px 24px;background:#fff0e2;border-bottom:1px solid #d7a775;white-space:pre-line}#notice button{background:transparent;border:1px solid #8d6544;border-radius:8px;padding:8px 16px;min-height:44px}.skip{position:fixed;left:16px;top:-100px;z-index:20;background:white;padding:12px}.skip:focus{top:12px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}.reduce-motion *{transition:none!important;animation:none!important}
@media(prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}
@media(max-width:360px){main{padding-inline:18px}.brand{padding-inline:18px}.today{padding:20px}.study-card{padding:20px;min-height:260px}.study-card p{font-size:1.35rem}.fill-equation{gap:6px;font-size:1.1rem}.choices{gap:8px}.primary,.secondary,.choice{padding-inline:12px}.results{gap:12px}}
@media(min-width:900px){.brand{padding-top:30px}main{padding-top:32px}.today{padding:32px}.heading h1{font-size:2rem}}