:root{--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light;--paper:#f7f2e7;--paper-2:#fffaf0;--paper-3:#efe4cf;--ink:#123f3c;--ink-2:#1d514b;--ink-soft:#4c6a64;--ink-faint:#123f3c1f;--ink-ghost:#123f3c0f;--coral:#df6a50;--coral-deep:#b8462c;--coral-soft:#f6d8ce;--gold:#dfa83d;--gold-deep:#b8862c;--gold-soft:#f5e1b4;--teal:#2f8279;--teal-deep:#1f5f58;--sky:#5586b3;--plum:#8a6a9e;--olive:#83955a;--danger:#b8462c;--stage-1:#0d3633;--stage-2:#092825;--cream:#fff8eb;--radius-xl:30px;--radius-lg:24px;--radius-md:18px;--radius-sm:12px;--shadow-panel:0 24px 60px -34px #123f3c8c, 0 1px 0 #ffffffb3 inset;--shadow-float:0 18px 42px -22px #09282599;--font-sans:"Apple SD Gothic Neo", "Pretendard", "Noto Sans KR", "Malgun Gothic", system-ui, -apple-system, sans-serif;--font-display:"Iowan Old Style", "Palatino Linotype", "Nanum Myeongjo", "Apple SD Gothic Neo", serif;--font-mono:"SF Mono", "Menlo", "Consolas", monospace;--header-h:78px;--focus-ring:3px solid 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svg{width:19px;height:19px}.icon-btn-soft{background:var(--ink-ghost);border-color:#0000}.link-btn{color:var(--ink-2);text-underline-offset:4px;align-items:center;gap:4px;padding:8px 2px;font-size:12.5px;font-weight:700;-webkit-text-decoration:underline #123f3c47;text-decoration:underline #123f3c47;transition:color .15s;display:inline-flex}.link-btn:hover{color:var(--coral-deep);text-decoration-color:currentColor}.segmented{background:var(--ink-ghost);border-radius:999px;gap:3px;width:100%;padding:3px;display:flex}.segmented-wrap{border-radius:var(--radius-sm);flex-wrap:wrap}.segmented-btn{min-height:34px;color:var(--ink-soft);white-space:nowrap;border-radius:999px;flex:auto;padding:6px 12px;font-size:12.5px;font-weight:700;transition:background-color .15s,color .15s,box-shadow .15s}.segmented-btn:hover:not(:disabled){color:var(--ink)}.segmented-btn.is-active{background:var(--paper-2);color:var(--ink);box-shadow:0 2px 8px -4px #09282580}.segmented-btn:disabled{opacity:.45}.segmented-dark{-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);background:#fff8eb1a;border:1px solid #fff8eb24;width:auto}.segmented-dark .segmented-btn{color:#fff8ebb3}.segmented-dark .segmented-btn:hover:not(:disabled){color:var(--cream)}.segmented-dark .segmented-btn.is-active{background:var(--cream);color:var(--ink)}.field{flex-direction:column;gap:7px;display:flex}.field-label{color:var(--ink-soft);letter-spacing:.12em;text-transform:uppercase;font-size:11px;font-weight:800}.select{border:1px solid var(--ink-faint);border-radius:var(--radius-sm);background-color:var(--paper-2);appearance:none;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1.5 6 6.5l5-5' fill='none' stroke='%23123f3c' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");background-position:right 13px center;background-repeat:no-repeat;width:100%;min-height:42px;padding:8px 36px 8px 13px;font-size:13px;font-weight:600}.select:hover{border-color:#123f3c42}.range-row{align-items:center;gap:12px;display:flex}.range{cursor:pointer;appearance:none;background:0 0;width:100%;height:32px;margin:0}.range::-webkit-slider-runnable-track{background:linear-gradient(90deg, var(--teal), var(--gold));border-radius:999px;height:8px}.range::-moz-range-track{background:linear-gradient(90deg, var(--teal), var(--gold));border-radius:999px;height:8px}.range::-webkit-slider-thumb{border:3px solid var(--coral);background:var(--paper-2);cursor:grab;appearance:none;border-radius:50%;width:26px;height:26px;margin-top:-9px;box-shadow:0 3px 8px -2px #09282573}.range::-moz-range-thumb{border:3px solid var(--coral);background:var(--paper-2);cursor:grab;border-radius:50%;width:20px;height:20px;box-shadow:0 3px 8px -2px #09282573}.range:active::-webkit-slider-thumb{cursor:grabbing}.range:active::-moz-range-thumb{cursor:grabbing}.range:focus-visible{outline:var(--focus-ring);outline-offset:2px;border-radius:999px}.range:disabled{opacity:.4;cursor:not-allowed}.range-value{min-width:58px;color:var(--ink);font-family:var(--font-mono);text-align:right;white-space:nowrap;font-size:12px;font-weight:700}.check{color:var(--ink-soft);cursor:pointer;align-items:center;gap:8px;font-size:12.5px;font-weight:600;display:inline-flex}.check input{width:16px;height:16px;accent-color:var(--coral);margin:0}.badge{color:var(--teal-deep);letter-spacing:.02em;background:#2f82791a;border:1px solid #2f827938;border-radius:999px;align-items:center;gap:6px;padding:4px 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svg{width:100%;height:100%}.brand-text{flex-direction:column;gap:1px;display:flex}.brand-name{font-family:var(--font-display);letter-spacing:-.015em;font-size:24px;font-weight:700;line-height:1.05}.brand-tagline{color:var(--ink-soft);letter-spacing:.02em;font-size:10.5px;font-weight:600}.main-nav{background:#fffaf0a6;border:1px solid #123f3c1a;border-radius:999px;align-items:center;gap:3px;margin-left:auto;padding:4px;display:flex}.nav-link{min-height:36px;color:var(--ink-soft);border-radius:999px;justify-content:center;align-items:center;padding:7px 18px;font-size:13px;font-weight:700;text-decoration:none;transition:background-color .16s,color .16s,box-shadow .16s;display:inline-flex}.nav-link:hover{color:var(--ink);background:var(--ink-ghost)}.nav-link.is-active{background:var(--ink);color:var(--cream);box-shadow:0 5px 14px -8px #092825cc}.header-chip{color:var(--gold-deep);letter-spacing:.06em;white-space:nowrap;background:#f5e1b46b;border:1px solid #dfa83d61;border-radius:999px;padding:6px 12px;font-size:10.5px;font-weight:800}.app-main{flex:1;grid-template-columns:minmax(230px,272px) minmax(0,1fr) minmax(306px,362px);align-items:start;gap:clamp(12px,1.7vw,24px);width:min(1580px,100%);margin:0 auto;padding:clamp(14px,2vw,26px) clamp(14px,2.5vw,34px) 32px;display:grid}.panel{top:calc(var(--header-h) + 12px);max-height:calc(100dvh - var(--header-h) - 46px);border-radius:var(--radius-lg);box-shadow:var(--shadow-panel);scrollbar-width:thin;scrollbar-color:#123f3c40 transparent;background:linear-gradient(160deg,#fffcf5eb,#faf3e5d6);border:1px solid #123f3c1a;flex-direction:column;gap:14px;padding:clamp(16px,1.6vw,22px);display:flex;position:sticky;overflow-y:auto}.panel::-webkit-scrollbar{width:6px}.panel::-webkit-scrollbar-thumb{background:#123f3c38;border-radius:999px}.panel-stack{flex-direction:column;gap:16px;display:flex}.panel-intro{flex-direction:column;gap:6px;display:flex}.panel-title{font-family:var(--font-display);letter-spacing:-.02em;font-size:clamp(22px,2vw,27px);font-weight:700;line-height:1.15}.panel-copy{color:var(--ink-soft);font-size:12.5px;line-height:1.55}.stage{top:calc(var(--header-h) + 12px);height:calc(100dvh - var(--header-h) - 46px);border-radius:var(--radius-xl);background:radial-gradient(120% 100% at 12% 0%, #1d5a54 0%, transparent 58%), radial-gradient(90% 100% at 100% 100%, #12433f 0%, transparent 62%), linear-gradient(150deg, var(--stage-1), var(--stage-2));isolation:isolate;min-height:480px;position:sticky;overflow:hidden;box-shadow:0 34px 70px -36px #092825bf,inset 0 1px 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svg{width:100%;height:100%}.solid-info{flex-direction:column;gap:1px;min-width:0;display:flex}.solid-name{letter-spacing:-.01em;font-size:14px}.solid-en{color:var(--ink-soft);letter-spacing:.08em;text-overflow:ellipsis;text-transform:uppercase;white-space:nowrap;font-size:9.5px;font-weight:700;overflow:hidden}.solid-meta{color:var(--ink-soft);margin-top:2px;font-size:10.5px;font-weight:600}.card{border-radius:var(--radius-md);background:#fffcf6a8;border:1px solid #123f3c1a;flex-direction:column;gap:12px;padding:clamp(15px,1.4vw,19px);display:flex}.card-accent{background:radial-gradient(120% 120% at 100% 0,#dfa83d2e,#0000 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.16s;position:relative}.switch:after{content:"";background:var(--paper-2);border-radius:50%;width:16px;height:16px;transition:transform .16s;position:absolute;top:3px;left:3px;box-shadow:0 2px 5px -1px #09282580}.switch-row input:checked+.switch-label+.switch,.switch-row input:checked~.switch{background:var(--teal)}.switch-row input:checked~.switch:after{transform:translate(16px)}.switch-row input:focus-visible~.switch{outline:var(--focus-ring);outline-offset:2px}.switch-label{font-size:12.5px;font-weight:700}.section-result{border-radius:var(--radius-sm);background:#fffaf08c;border:1px dashed 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11px;display:flex}.formula-label{color:var(--ink-soft);letter-spacing:.1em;text-transform:uppercase;font-size:9.5px;font-weight:800}.formula-main{font-family:var(--font-mono);white-space:pre-wrap;font-size:11.5px;font-weight:700}.formula-sub{color:var(--ink-soft);font-family:var(--font-mono);font-size:11px}.formula-note{color:var(--ink-soft);font-size:10.5px;line-height:1.5}.challenge-next{color:var(--ink);font-size:13.5px;font-weight:600;line-height:1.55}.challenge-stars{color:var(--gold-deep);letter-spacing:.03em;font-size:11.5px;font-weight:700}.mobile-tabs{background:#fffaf0d9;border:1px solid #123f3c1a;border-radius:999px;gap:3px;padding:4px;display:none}.mobile-tab{min-height:38px;color:var(--ink-soft);border-radius:999px;flex:1;font-size:12px;font-weight:700}.mobile-tab.is-active{background:var(--ink);color:var(--cream)}.challenge-list{flex-direction:column;gap:7px;display:flex}.challenge-item{border-radius:var(--radius-md);text-align:left;background:#fffaf08c;border:1px solid #0000;align-items:flex-start;gap:10px;width:100%;padding:10px;transition:background-color .15s,border-color .15s,transform .15s;display:flex}.challenge-item:hover{background:#fffaf0eb;border-color:#123f3c29}.challenge-item.is-active{background:#f6d8ce6b;border-color:#df6a5066}.challenge-item.is-done:not(.is-active){background:#2f827912}.challenge-item-index{background:var(--ink-ghost);width:26px;height:26px;color:var(--ink-soft);font-family:var(--font-mono);border-radius:50%;flex:none;justify-content:center;align-items:center;font-size:11px;font-weight:800;display:inline-flex}.challenge-item.is-active .challenge-item-index{background:var(--coral);color:var(--cream)}.challenge-item.is-done:not(.is-active) .challenge-item-index{background:var(--teal);color:var(--cream)}.challenge-item-body{flex-direction:column;flex:1;gap:3px;min-width:0;display:flex}.challenge-item-title{flex-direction:column;gap:1px;display:flex}.challenge-item-type{color:var(--coral-deep);letter-spacing:.1em;text-transform:uppercase;font-size:9px;font-weight:800}.challenge-item-prompt{-webkit-line-clamp:2;-webkit-box-orient:vertical;font-size:11.5px;font-weight:600;line-height:1.4;display:-webkit-box;overflow:hidden}.challenge-item-stars{color:var(--gold-deep);letter-spacing:.08em;min-height:12px;font-size:10px}.challenge-panel{gap:13px}.challenge-head{flex-direction:column;gap:7px;display:flex}.challenge-eyebrow-row{justify-content:space-between;align-items:center;gap:8px;display:flex}.difficulty{color:var(--gold-deep);letter-spacing:.08em;font-size:10px;font-weight:800}.progress-row{align-items:center;gap:10px;display:flex}.progress-dots{flex-wrap:wrap;flex:1;gap:4px;display:flex}.progress-dot{background:#123f3c29;border-radius:50%;width:7px;height:7px}.progress-dot.is-done{background:var(--teal)}.progress-dot.is-current{background:var(--coral);box-shadow:0 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#dfa83d21}.option.is-correct{border-color:var(--teal);background:#2f82791f}.option.is-wrong{border-color:var(--coral);background:#df6a501f}.option-letter{background:var(--ink-ghost);width:27px;height:27px;color:var(--ink-soft);font-family:var(--font-mono);border-radius:50%;flex:none;justify-content:center;align-items:center;font-size:11px;font-weight:800;display:inline-flex}.option.is-selected .option-letter{background:var(--gold);color:var(--ink)}.option.is-correct .option-letter{background:var(--teal);color:var(--cream)}.option.is-wrong .option-letter{background:var(--coral);color:var(--cream)}.option-text{flex:1;font-size:13.5px;font-weight:600;line-height:1.4}.option-mark{color:var(--ink-soft);letter-spacing:.06em;font-size:9.5px;font-weight:800}.option.is-correct .option-mark{color:var(--teal-deep)}.option.is-wrong .option-mark{color:var(--coral-deep)}.challenge-submit{width:100%}.challenge-feedback{border-radius:var(--radius-sm);padding:10px 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span{color:var(--ink-soft);font-size:10.5px;font-weight:700}.answer-key{flex-direction:column;gap:9px;display:flex}.answer-item{border-radius:var(--radius-md);background:#fffaf08c;border:1px solid #123f3c1a;flex-direction:column;gap:7px;padding:12px;display:flex}.answer-head{flex-direction:column;gap:3px;display:flex}.answer-title{align-items:flex-start;gap:8px;font-size:12.5px;line-height:1.45;display:flex}.answer-index{background:var(--ink);width:22px;height:22px;color:var(--cream);font-family:var(--font-mono);border-radius:50%;flex:none;justify-content:center;align-items:center;font-size:10px;display:inline-flex}.answer-meta{color:var(--ink-soft);letter-spacing:.04em;font-size:10px;font-weight:700}.answer-status{color:var(--ink-soft);font-size:11px}.answer-solution{border-left:3px solid var(--gold);background:#f5e1b433;border-radius:0 9px 9px 0;padding:9px 10px;font-size:12px;line-height:1.55}.answer-solution strong{color:var(--gold-deep);letter-spacing:.03em;margin-bottom:2px;font-size:11px;display:block}.empty-state{border-radius:var(--radius-md);color:var(--ink-soft);text-align:center;border:1px dashed #123f3c2e;padding:18px;font-size:12.5px}.worksheet{display:none}@media (max-width:1180px){.app-main{grid-template-columns:minmax(210px,250px) minmax(0,1fr)}.stage{position:relative;top:0}.panel-left{max-height:none;position:static;overflow:visible}.panel-right{grid-column:1/-1;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));align-items:start;max-height:none;display:grid;position:static;overflow:visible}.panel-right .mobile-tabs{display:none}.panel-right .card-accent{grid-column:1/-1}}@media (min-width:881px) and (max-width:1180px){body[data-route=challenge] .stage{height:min(60dvh,520px);min-height:380px}body[data-route=teacher] .stage{height:min(52dvh,460px);min-height:340px}}@media (max-width:880px){.app-main{grid-template-columns:minmax(0,1fr);padding-bottom:26px}.stage{order:1;height:min(58dvh,560px);min-height:380px;position:relative;top:0}body[data-route=challenge] .stage{height:min(44dvh,400px);min-height:300px}body[data-route=teacher] .stage{height:min(38dvh,340px);min-height:270px}.panel-right{flex-direction:column;order:2;align-items:stretch;gap:12px;display:flex}.panel-left{order:3;max-height:none;position:static;overflow:visible}body[data-route=teacher] .panel-left{order:2}body[data-route=teacher] .panel-right{order:3}.mobile-tabs,.panel-right .mobile-tabs{top:calc(var(--header-h) + 6px);z-index:8;-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px);display:flex;position:sticky}.panel-right .card:not(.is-mobile-active){display:none}.solid-list{scroll-snap-type:x proximity;scrollbar-width:thin;flex-direction:row;padding-bottom:4px;display:flex;overflow-x:auto}.solid-card{scroll-snap-align:start;min-width:168px}.challenge-list{grid-template-columns:repeat(auto-fit,minmax(230px,1fr));display:grid}.stage-hint{display:none}.stage-lower{bottom:16px;left:18px;right:18px}.stage-badges{top:72px;left:18px;right:18px}}@media (max-width:620px){:root{--header-h:66px}body{font-size:14.5px}.app-header{gap:10px;padding:10px 14px}.brand-mark{width:36px;height:36px}.brand-name{font-size:21px}.brand-tagline,.header-chip{display:none}.main-nav{margin-left:auto}.nav-link{min-height:42px;padding:8px 13px;font-size:12px}.segmented-btn{min-height:42px}.mobile-tab{min-height:44px}.app-main{gap:10px;padding:10px 10px 22px}.stage{border-radius:var(--radius-lg);height:min(52dvh,460px);min-height:330px}.stage-region:focus-visible{border-radius:var(--radius-lg)}.stage-toolbar{top:10px;left:10px;right:10px}.preset-group{display:none}.segmented-dark{width:100%}.segmented-dark .segmented-btn{flex:1}.stage-badges{top:62px;left:14px;right:14px}.stage-title{font-size:24px}.stage-subtitle{font-size:10px}.stage-lower{bottom:12px;left:14px;right:14px}.stage-face-label,.stage-section-label{font-size:10.5px}.panel{border-radius:var(--radius-md);padding:15px}.panel-left .panel-stack{gap:12px}.panel-left .panel-copy{display:none}.panel-left .panel-intro{gap:3px}.panel-title{font-size:22px}.card{padding:15px}.btn{min-height:46px;padding:11px 18px}.icon-btn{width:46px;height:46px}.option{min-height:52px}.challenge-actions .btn{flex:100%}.challenge-nav{margin-top:2px}.mobile-tabs{top:calc(var(--header-h) + 4px);position:sticky}}@media print{@page{margin:16mm}body{color:#000;background:#fff!important}body.printing .app-shell,body.printing #announcer{display:none!important}.worksheet{color:#000;font-family:var(--font-sans);display:block}.worksheet-head h1{margin-bottom:4px;font-size:24px}.worksheet-head p{margin-bottom:14px;font-size:12px}.worksheet-info{border-bottom:2px solid #000;justify-content:space-between;gap:24px;padding:10px 0 14px;font-size:12px;display:flex}.worksheet-item{break-inside:avoid;border-bottom:1px solid #bbb;padding:14px 0}.worksheet-item h2{font-size:14px;line-height:1.5}.worksheet-options{margin-top:5px;font-size:12px}.worksheet-lines{background-image:repeating-linear-gradient(#0000 0 25px,#ccc 25px 26px);height:54px;margin-top:8px}}