.ls-shell{max-width:1000px;margin:0 auto;padding:24px 22px 48px}.ls-top-nav,.ls-actions{flex-wrap:wrap;align-items:center;gap:12px;display:flex}.ls-top-nav{color:var(--mist);justify-content:space-between;font-size:12px}.ls-top-nav a{align-items:center;min-height:44px;display:inline-flex}.ls-header{margin:20px 0 24px}.ls-header h1{font:700 clamp(32px, 5vw, 48px)/1.2 var(--font-display);margin:6px 0 10px}.ls-header>p:last-child{color:var(--mist);font-size:14px}.ls-eyebrow{font:10px var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--glow)}.ls-parts{grid-template-columns:repeat(3,minmax(0,1fr));gap:8px;margin-bottom:24px;display:grid}.ls-parts button{text-align:left;border:1px solid var(--border);background:var(--panel);border-radius:12px;min-height:65px;padding:10px 12px}.ls-parts span{color:var(--mist);font:10px var(--font-mono);margin-bottom:5px;display:block}.ls-parts strong{font:600 14px var(--font-display)}.ls-parts .is-active{border-color:var(--glow);background:color-mix(in oklch, var(--glow) 10%, var(--panel))}.ls-parts .is-active strong{color:var(--glow)}.ls-lesson{border-radius:22px;max-width:760px;margin:0 auto;padding:26px}.ls-lesson h2{font:600 clamp(21px, 3vw, 27px)/1.3 var(--font-display);margin:10px 0 18px}.ls-lesson p{margin:10px 0;font-size:14px;line-height:1.6}.ls-objects{gap:28px;margin:22px 0;display:flex}.ls-objects>div{color:var(--glow);align-items:center;gap:10px;display:flex}.ls-objects>div:last-child{color:var(--violet)}.ls-objects span{color:var(--ice);font-size:14px}.ls-originals{z-index:3;background:var(--panel);border:1px solid var(--border);box-shadow:0 4px 14px color-mix(in oklch, var(--ink) 30%, transparent);border-radius:12px;margin:16px 0;padding:10px 14px;position:sticky;top:8px}.ls-originals>div{align-items:center;gap:14px;display:flex}.ls-equation-number{color:var(--mist);font:11px var(--font-mono)}.ls-math{min-width:0;max-width:100%;padding:8px 0;font-size:22px}.ls-math>span{max-width:100%;display:inline-block}.ls-teaching-lines{padding:0;list-style:none}.ls-teaching-lines li{border-left:2px solid var(--border);margin:8px 0;padding:5px 12px}.ls-teaching-lines .is-current{border-left-color:var(--glow);background:color-mix(in oklch, var(--glow) 5%, transparent)}.ls-teaching-lines p{color:var(--mist);margin:0 0 4px;font-size:13px}.ls-next-step,.ls-current-question{margin-top:16px;scroll-margin:165px}.ls-next-step{flex-wrap:wrap;align-items:center;gap:12px;display:flex}.ls-answer{color:var(--glow);flex-basis:100%}.ls-instruction{color:var(--ice);font-weight:500}.ls-button{min-height:48px;font:600 14px var(--font-display);border-radius:12px;justify-content:center;align-items:center;padding:12px 18px;display:inline-flex}.ls-primary{background:var(--glow);color:var(--ink)}.ls-text-button{color:var(--glow);text-underline-offset:4px;text-align:left;min-height:44px;font-size:13px;text-decoration:underline}.ls-fields{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:16px 0;display:grid}.ls-fields>:only-child{grid-column:1/-1;max-width:400px}.ls-field{min-width:0;display:block}.ls-field>span:first-child{color:var(--mist);margin-bottom:7px;font-size:12px;display:block}.ls-input-row{align-items:center;gap:6px;display:flex}.ls-field input{border:1px solid var(--input);background:var(--ink);width:100%;min-width:0;min-height:54px;color:var(--ice);text-align:center;font:22px var(--font-mono);border-radius:12px;padding:10px}.ls-field input::placeholder{color:var(--mist);font-size:11px}.ls-sign{border:1px solid var(--border);min-width:44px;min-height:44px;color:var(--mist);border-radius:9px}.ls-choices{gap:10px;margin:16px 0;display:grid}.ls-choice{text-align:left;border:1px solid var(--input);background:var(--ink);min-height:50px;color:var(--ice);border-radius:12px;padding:10px 14px;font-size:14px}.ls-choice:hover{border-color:var(--glow)}.ls-choice .ls-math{padding:0}.ls-feedback,.ls-hint{border-left:3px solid var(--amber);background:var(--panel);border-radius:0 10px 10px 0;margin:14px 0;padding:10px 14px}.ls-hint{border-color:var(--glow)}.ls-hint p{margin:0}.ls-addition-stack{border:1px solid var(--border);background:var(--ink);border-radius:12px;margin:14px 0;padding:12px}.ls-addition-row{text-align:center;grid-template-columns:20px minmax(0,1fr) minmax(0,1fr) 18px minmax(0,1fr);align-items:center;gap:4px;display:grid}.ls-addition-row:nth-child(2){border-bottom:1px solid var(--mist)}.ls-stack-term,.ls-addition-row>span:last-child{border-radius:8px}.ls-addition-row .is-marked{background:color-mix(in oklch, var(--glow) 18%, transparent);outline:1px solid var(--glow)}.ls-addition-row .is-zero{background:color-mix(in oklch, var(--violet) 14%, transparent);color:var(--violet);text-decoration:line-through}.ls-addition-stack figcaption{color:var(--mist);margin-top:10px;font-size:12px;line-height:1.5}.ls-further{background:var(--panel);border:1px solid var(--border);border-radius:14px;max-width:760px;margin:24px auto 0;padding:16px;font-size:13px}.ls-further summary{cursor:pointer;min-height:34px;color:var(--glow)}.ls-further p{color:var(--mist);margin:10px 0}.ls-further label{margin:8px 0;display:block}.ls-further select{border:1px solid var(--input);background:var(--ink);width:100%;min-height:48px;color:var(--ice);border-radius:10px;padding:10px}.ls-level-title{color:var(--mist);max-width:760px;margin:0 auto 12px;font-size:13px}.ls-review-nav{max-width:760px;margin:14px auto}.ls-footer{border-top:1px solid var(--border);color:var(--mist);flex-wrap:wrap;justify-content:space-between;align-items:center;gap:14px;margin-top:32px;padding-top:20px;font-size:12px;display:flex}.ls-footer>p{flex-basis:100%}.ls-footer>a{color:var(--glow);text-decoration:underline}.ls-shell button:focus-visible,.ls-shell a:focus-visible,.ls-shell input:focus-visible,.ls-shell select:focus-visible,.ls-shell summary:focus-visible{outline:3px solid var(--glow);outline-offset:3px}@media (width<=600px){.ls-shell{padding:14px 14px 32px}.ls-parts{gap:6px}.ls-parts button{min-height:72px;padding:9px}.ls-parts strong{font-size:11px;line-height:1.3}.ls-lesson{border-radius:18px;padding:16px}.ls-lesson p{font-size:13px}.ls-originals{padding:8px 10px;top:4px}.ls-math{font-size:18px}.ls-fields{grid-template-columns:1fr;gap:10px}.ls-field input{padding:8px 5px;font-size:20px}.ls-field input::placeholder{font-size:9px}.ls-field>span:first-child{font-size:11px}.ls-objects{gap:16px}.ls-objects span{font-size:12px}.ls-addition-stack{padding:8px}.ls-addition-row{grid-template-columns:14px minmax(0,1fr) minmax(0,1fr) 14px minmax(0,1fr)}}.ls-board{z-index:3;background:var(--panel);border-radius:12px;position:sticky;top:8px}.ls-board .ls-addition-stack{background:var(--panel)}.ls-parts{grid-template-columns:repeat(5,minmax(0,1fr))}.ls-secondary{border:1px solid var(--border);background:var(--panel);color:var(--ice)}.ls-methods .is-active{border-color:var(--glow);color:var(--glow)}.ls-task-meta,.ls-level-picker,.ls-methods,.ls-session-count{max-width:760px;margin:14px auto}.ls-task-meta p,.ls-session-count{color:var(--mist);font-size:12px;line-height:1.5}.ls-task-meta p:first-child{color:var(--glow)}.ls-level-picker label{color:var(--mist);margin-bottom:7px;font-size:12px;display:block}.ls-level-picker select{border:1px solid var(--input);background:var(--panel);width:100%;min-height:48px;color:var(--ice);border-radius:12px;padding:10px 14px}.ls-methods{flex-wrap:wrap;gap:10px;display:flex}.ls-task-bottom{border-top:1px solid var(--border);flex-wrap:wrap;align-items:center;gap:12px;margin-top:22px;padding-top:18px;display:flex}.ls-help-actions{margin-top:14px}.ls-close-help{margin-top:10px;display:block}.ls-back-to-task{max-width:760px;margin:12px auto;display:block}.ls-check-originals{width:100%;color:var(--mist);font-size:13px}.ls-check-originals summary{cursor:pointer;align-items:center;min-height:44px;display:flex}@media (width<=600px){.ls-parts{grid-template-columns:repeat(2,minmax(0,1fr))}.ls-parts button:last-child{grid-column:1/-1;min-height:54px}.ls-parts strong{font-size:13px}.ls-parts button{min-height:62px}.ls-task-bottom{flex-direction:column;align-items:stretch}.ls-methods .ls-button{flex:1;padding:10px;font-size:12px}}.ls-diff-picker{grid-template-columns:repeat(3,1fr);gap:10px;display:grid}.ls-diff{border:1px solid var(--color-border);background:color-mix(in oklab, var(--color-ink) 55%, transparent);text-align:left;cursor:pointer;border-radius:18px;flex-direction:column;gap:4px;padding:14px;transition:transform .2s,border-color .2s;display:flex}.ls-diff:hover{transform:translateY(-2px)}.ls-diff.is-active{border-color:var(--color-glow);background:color-mix(in oklab, var(--color-glow) 12%, transparent)}.ls-diff-title{font-family:var(--font-display);font-size:15px;font-weight:600}.ls-diff-desc{color:var(--color-mist);font-size:12px}.ls-diff-count{font-family:var(--font-mono);color:var(--color-glow);font-size:11px}@media (width<=560px){.ls-diff-picker{grid-template-columns:1fr}}.bo-room{border:1px solid var(--color-border);border-radius:18px;width:100%;max-width:520px;margin:0 auto;display:block}.bo-wall{fill:#141824}.bo-floor{fill:#0d1018}.bo-off{fill:#2a3040}.bo-lamp-on{fill:#ffd76a}.bo-beam{fill:#ffd76a;opacity:.18}.bo-panel-on{fill:#1d3a4a;stroke:#58c4dc;stroke-width:1.5px}.bo-light-on{fill:#6ef2a5}.bo-screen-on{fill:#58c4dc;opacity:.8}.bo-fan-on{fill:#22303f;stroke:#8fb6ff;stroke-width:1.5px}.bo-blade-on{fill:#8fb6ff}.bo-doorframe{fill:none;stroke:#3a4358;stroke-width:2px}.bo-door-closed{fill:#232a3a}.bo-door-open{fill:#0d1018}.bo-doorway-light{fill:#ffd76a;opacity:.35}.bo-darkness{fill:#05070d;pointer-events:none;transition:opacity .8s}@media (prefers-reduced-motion:reduce){.bo-darkness{transition:none}}.det-steps{flex-direction:column;gap:8px;margin:0;padding:0;list-style:none;display:flex}.det-step{text-align:left;border:1px solid var(--color-border);background:color-mix(in oklab, var(--color-ink) 55%, transparent);cursor:pointer;border-radius:12px;width:100%;padding:10px 14px;transition:border-color .2s}.det-step:not(:disabled):hover{border-color:var(--color-glow)}.det-step:disabled{cursor:default}.det-step.is-error{border-color:var(--color-flame);background:color-mix(in oklab, var(--color-flame) 12%, transparent)}.det-case-list{grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:12px;display:grid}.det-case{border:1px solid var(--color-border);background:color-mix(in oklab, var(--color-ink) 55%, transparent);text-align:left;cursor:pointer;border-radius:18px;flex-direction:column;gap:4px;padding:16px;transition:transform .2s,border-color .2s;display:flex}.det-case:hover{border-color:var(--color-glow);transform:translateY(-2px)}.ls-originals>div.is-active{border-color:var(--glow);background:color-mix(in oklch, var(--glow) 10%, transparent)}.ls-choice.is-wrong{border-color:var(--amber);opacity:.75}.ls-guided-progress{font-family:var(--font-mono);letter-spacing:.15em;text-transform:uppercase;color:var(--mist);margin:18px 0 4px;font-size:11px}.ls-guided-question h3{margin:0 0 4px;font-size:18px}.ls-workspace{min-width:0}.ls-workspace .ls-originals{box-shadow:none;margin:18px 0 28px;position:static}.ls-workspace .ls-originals>div{border-radius:6px;padding:4px 6px}.ls-work-expression{font-size:26px;line-height:1.6}.ls-equation-number{flex-shrink:0}.ls-calculation{border-left:2px solid var(--border);padding:0 0 0 18px;list-style:none}.ls-calculation li{padding:8px 8px 18px}.ls-operation-caption{color:var(--mist);margin-bottom:6px;font-size:12px}.ls-expression-scroll{max-width:100%;padding:5px 0;overflow-x:auto}.ls-new-line{animation:.45s ease-out ls-reveal}.ls-active-actions{padding:20px 0 8px;scroll-margin-block:20px}.ls-active-actions h3{margin-bottom:14px}.ls-active-actions .ls-operation{border-radius:8px;width:100%;margin-bottom:8px;display:flex}.ls-operation:hover{border-color:var(--glow)}@keyframes ls-reveal{0%{opacity:.4;background:color-mix(in oklch, var(--glow) 14%, transparent);transform:translateY(6px)}to{opacity:1;background:0 0;transform:translateY(0)}}@media (width<=600px){.ls-work-expression{font-size:21px}.ls-calculation{padding-left:10px}}@media (prefers-reduced-motion:reduce){.ls-new-line{animation:none}}
