:root{font-family:system-ui,-apple-system,'Noto Sans KR',sans-serif;color:#192b47;background:#eef3fa;font-size:16px}*{box-sizing:border-box}body{margin:0}button,input,textarea{font:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid #f0ad49;outline-offset:2px}header{height:72px;background:#11223e;color:#fff;display:flex;justify-content:space-between;align-items:center;gap:14px;padding:0 26px}.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:inherit}.brandMark{font-size:31px;color:#87b9fc}.brand strong{font-size:17px;display:block}.brand small{display:block;color:#9eb7db;margin-top:2px;font-size:12px}.headerActions{display:flex;align-items:center;gap:8px}.headerLink,header button{border:1px solid #496387;background:#213b62;border-radius:9px;padding:8px 12px;color:#d9e9ff;text-decoration:none;font-size:13px}.headerLink:hover,header button:hover{background:#31527e}.layout{display:grid;grid-template-columns:260px minmax(0,1fr);min-height:calc(100vh - 72px)}.sidebar{background:#192f51;color:#d5e3f6;padding:20px 13px;display:flex;flex-direction:column;gap:14px}.sidebarHead{padding:0 9px}.sidebarHead p{margin:0 0 10px;font-weight:700;font-size:14px}.progressTrack{height:7px;border-radius:8px;background:#304c73;overflow:hidden}.progressTrack span{display:block;background:#6dbdb7;height:100%;width:0;transition:width .3s}.sidebarHead small{font-size:12px;color:#a7bddb;display:block;margin-top:7px}.levelGroup{display:flex;background:#0f2441;border:1px solid #4b658b;border-radius:9px;padding:3px}.levelGroup button{flex:1;border:0;background:none;color:#b8cce7;border-radius:6px;padding:8px 0;font-size:13px}.levelGroup button.active{background:#3c6cc5;color:white;font-weight:700}.searchLabel{font-size:12px;color:#a7bddb;padding:0 4px}.searchLabel input{display:block;width:100%;margin-top:6px;padding:9px 10px;border:1px solid #4b6487;border-radius:8px;background:#112541;color:#fff}.searchLabel input::placeholder{color:#8097b8}.sidebar nav{display:grid;gap:3px;overflow-y:auto;max-height:calc(100vh - 315px);min-height:250px}.navGroup{font-size:11px;font-weight:700;color:#88a8d0;letter-spacing:.12em;margin:14px 9px 5px}.navItem{display:flex;gap:8px;align-items:center;width:100%;text-align:left;background:none;border:0;color:#d3e0f3;border-radius:8px;padding:10px 9px;font-size:13px;line-height:1.35}.navItem:hover{background:#2a476f}.navItem.active{background:#345b96;color:white;font-weight:700}.navItem .num{font:11px ui-monospace,monospace;min-width:20px;color:#92b3dd}.navItem.active .num{color:#e5f1ff}.navItem .done{margin-left:auto;color:#80e0b8}.sidebarFoot{margin-top:auto;padding:14px 8px 0;border-top:1px solid #355176;color:#a0b7d5;font-size:12px;line-height:1.5}main{min-width:0;padding:25px 30px;max-width:1600px;width:100%}.crumb{font-size:12px;color:#657b98;margin:0 0 9px}.lessonHeader{display:flex;align-items:flex-start;justify-content:space-between;gap:15px;margin-bottom:15px}.lessonHeader h1{font-size:30px;letter-spacing:-.04em;margin:4px 0 5px}.lessonHeader p{margin:0;color:#617592;font-size:14px;line-height:1.5}.eyebrow{font-size:11px;letter-spacing:.1em;color:#3769ad;font-weight:800}.lessonActions{display:flex;gap:6px;white-space:nowrap}.lessonActions button,.navigatorButtons button{background:white;border:1px solid #cbd9e9;border-radius:8px;padding:8px 11px;color:#31537e;font-size:13px}.lessonActions button:disabled{opacity:.4;cursor:default}.learningPath{display:flex;gap:6px;margin:16px 0;flex-wrap:wrap}.learningPath span{padding:7px 12px;background:#e1e9f5;border-radius:20px;color:#5d7392;font-size:12px}.learningPath span.active{background:#d9eafb;color:#245caa;font-weight:700}.contentGrid{display:grid;grid-template-columns:minmax(0,1.9fr) minmax(275px,.75fr);align-items:start;gap:16px}.mainColumn,.sideColumn{display:grid;gap:16px;min-width:0}.card{border:1px solid #d8e2ef;border-radius:14px;background:white;box-shadow:0 3px 15px #243f6908;padding:20px}.cardTop{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:-2px 0 15px}.card h2{font-size:18px;margin:0;letter-spacing:-.02em}.cardTop span{font-size:12px;color:#657c9c}.conceptText{font-size:16px;line-height:1.75;margin:0 0 16px;white-space:pre-line}.formulaRow{display:grid;grid-template-columns:1fr 1fr;gap:10px}.formulaRow>div{background:#edf4fd;border:1px solid #dce7f6;border-radius:9px;padding:13px}.formulaRow small{display:block;color:#5f789e;margin-bottom:7px}.formulaRow strong{font:700 20px/1.3 ui-monospace,monospace;color:#2459a8}.formulaRow span{font-size:13px;color:#435a7a;line-height:1.5}.misconception{border-left:3px solid #e6ad58;background:#fff8eb;border-radius:4px;padding:10px 13px;margin-top:14px;font-size:13px}.misconception b{color:#946029}.misconception p{margin:5px 0 0;line-height:1.55;color:#675941}.labPrompt{font-size:14px;color:#415e83;line-height:1.6;margin-top:-4px}.predict{display:flex;align-items:center;gap:8px;padding:11px;background:#f5f8fd;border:1px solid #e2eaf4;border-radius:9px}.predict label{font-size:13px;font-weight:700;color:#486384;white-space:nowrap}.predict input{flex:1;min-width:80px;border:1px solid #cbd9ea;border-radius:7px;padding:8px}.predict button,.reflection button,.quiz button,#completeLesson{border:1px solid #aac3e5;background:#eaf2ff;color:#2458a3;border-radius:7px;padding:8px 11px;font-size:13px}.labSurface{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(240px,.9fr);gap:12px;margin-top:14px}.diagram{border:1px solid #dce6f2;border-radius:10px;background:#f8fbff;padding:11px;min-width:0}.diagram svg{width:100%;height:195px}.diagramCaption{font-size:12px;color:#697f9d;line-height:1.5}.controls{display:grid;gap:10px}.control{padding:9px 10px;background:#f5f8fc;border:1px solid #e0e9f3;border-radius:9px}.controlTop{display:flex;justify-content:space-between;gap:10px;font-size:13px}.controlTop b{color:#245aad;font-variant-numeric:tabular-nums}.control input[type=range]{width:100%;accent-color:#346cd0;margin:10px 0 0}.resultHeader{display:flex;justify-content:space-between;align-items:center;margin:17px 0 9px}.resultHeader h3{font-size:15px;margin:0}.resultHeader span{color:#8192aa;font-size:12px}.results{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}.result{background:#eaf2ff;border:1px solid #dae8f9;border-radius:9px;padding:12px;min-width:0}.result b{display:block;color:#1d4c9b;font-size:21px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.result span{display:block;margin-top:4px;font-size:12px;color:#5f7698}#plot{width:100%;height:170px;background:#fbfdff;border:1px solid #e1e9f3;border-radius:9px;margin-top:11px}.modelLimit{font-size:12px;color:#657b9a;line-height:1.5;margin:8px 0 0}.reflectionGrid{display:grid;grid-template-columns:1fr 1fr;gap:12px}.reflectionGrid label{font-size:13px;color:#536a89}.reflectionGrid textarea{display:block;margin-top:7px;width:100%;min-height:88px;resize:vertical;border:1px solid #cad9e9;border-radius:8px;padding:10px;font-size:13px;line-height:1.5}.reflection button{margin-top:10px}#savedMessage{margin-left:8px;font-size:12px;color:#34715e}.quiz p{line-height:1.6}.quizChoices{display:grid;gap:7px}.quizChoices button{text-align:left;background:#f7faff;border-color:#d9e4f2;color:#355273}.quizChoices button.selected{border-color:#3771d0;background:#e9f2ff}.quizChoices button.correct{border-color:#39a876;background:#e8f9ee}.quizChoices button.wrong{border-color:#cf6674;background:#fff0f2}#quizFeedback{min-height:25px;color:#2b649e;font-size:13px}#completeLesson{background:#2f68c9;color:white;border-color:#2f68c9}#completeLesson:disabled{opacity:.45;cursor:default}.sideColumn .card{padding:18px}.sideColumn h2{font-size:16px}.sideColumn p,.sideColumn li{font-size:13px;line-height:1.65;color:#526a89}.sideColumn ul{padding-left:20px;margin-bottom:14px}.skillTag{display:inline-block;background:#e8efff;color:#315cad;border-radius:20px;font-size:12px;padding:6px 10px}.application a{font-size:13px;color:#2761b9;font-weight:700;text-decoration:none}.application a:hover{text-decoration:underline}.designCheck p{border-top:1px solid #e6edf5;padding-top:10px;margin-bottom:0}.navigatorButtons{display:flex;gap:7px}footer{padding:18px 0;color:#7184a0;font-size:12px;line-height:1.5}@media(max-width:1200px){.contentGrid{grid-template-columns:1fr}.sideColumn{grid-template-columns:repeat(2,1fr)}}@media(max-width:850px){.layout{display:block}.sidebar{display:block;padding:10px}.sidebarHead,.sidebarFoot{display:none}.levelGroup{max-width:280px;float:right}.searchLabel{display:block;max-width:360px}.sidebar nav{display:flex;overflow-x:auto;min-height:0;max-height:none;gap:4px;margin-top:8px}.navGroup{display:none}.navItem{flex:none;width:auto;white-space:nowrap}main{padding:20px}.labSurface{grid-template-columns:1fr 1fr}}@media(max-width:620px){header{height:auto;min-height:65px;padding:10px}.brand strong{font-size:13px}.headerActions{gap:4px}.headerLink,header button{font-size:11px;padding:5px}.headerLink:nth-child(2){display:none}.levelGroup{float:none;margin:9px 0}.sidebar nav{margin-top:8px}.lessonHeader{display:block}.lessonActions{margin-top:12px}.lessonHeader h1{font-size:25px}.contentGrid,.labSurface,.formulaRow,.reflectionGrid,.sideColumn{grid-template-columns:1fr}.results{grid-template-columns:1fr}.predict{flex-wrap:wrap}.predict input{min-width:100%;order:2}.predict button{order:3}}
/* Curriculum interactions */
#courseNav h3{font-size:11px;font-weight:700;color:#88a8d0;letter-spacing:.09em;margin:14px 9px 5px}.navLesson{display:flex;gap:8px;align-items:center;width:100%;text-align:left;background:none;border:0;color:#d3e0f3;border-radius:8px;padding:10px 9px;font-size:13px;line-height:1.35}.navLesson:hover{background:#2a476f}.navLesson.active{background:#345b96;color:#fff;font-weight:700}.navNum{font:11px ui-monospace,monospace;min-width:20px;color:#92b3dd}.navDone{margin-left:auto;color:#80e0b8}.noResults{color:#b8cce7;font-size:13px;padding:8px}.control>span{display:flex;justify-content:space-between;gap:10px;font-size:13px}.control strong{color:#245aad;font-variant-numeric:tabular-nums}.control small{display:block;color:#7b90a9;font-size:11px}.metric{background:#eaf2ff;border:1px solid #dae8f9;border-radius:9px;padding:12px;min-width:0}.metric strong{display:block;color:#1d4c9b;font-size:20px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.metric small{display:block;margin-bottom:4px;font-size:12px;color:#5f7698}.learningPath span.done{background:#d8f3e9;color:#187353}@media(max-width:850px){#courseNav h3{display:none}.navLesson{flex:none;width:auto;white-space:nowrap}}@media(max-width:620px){.metric strong{font-size:18px}}
.stageLead{display:inline-flex;background:#e4f1ff;color:#18559e;padding:7px 11px;border-radius:7px;font-size:13px;font-weight:700;margin-bottom:13px}.storyBox{background:linear-gradient(110deg,#f1f8ff,#f6fbf7);border:1px solid #d8e8f5;border-radius:10px;padding:15px 18px;margin:5px 0 16px}.storyBox span{font-size:12px;color:#2273a4;font-weight:800}.storyBox p{font-size:15px;line-height:1.75;margin:7px 0 0}.missionBox{display:flex;justify-content:space-between;gap:15px;align-items:center;background:#fff8ed;border:1px solid #f0d6a9;border-radius:10px;padding:12px 15px;margin-top:14px}.missionBox strong{font-size:14px;color:#78491b}.missionBox p{font-size:13px;line-height:1.55;margin:4px 0 0;color:#805e35}.missionBox>span{white-space:nowrap;background:#fae8ca;color:#8b5518;border-radius:20px;padding:7px 10px;font-size:12px}.missionBox>span.achieved{background:#d9f5e8;color:#166442}.comparison{margin-top:10px;padding:10px 12px;background:#eef8f7;border:1px solid #cce8e3;border-radius:8px;font-size:13px;color:#27635a;line-height:1.5}@media(max-width:620px){.missionBox{display:block}.missionBox>span{display:inline-block;margin-top:10px}}
.opening{position:relative;overflow:hidden;background:linear-gradient(125deg,#173960,#246daa);border-radius:13px;padding:23px 25px;color:white;margin:0 0 16px}.opening:after{content:'?';position:absolute;right:24px;top:-30px;font-size:150px;line-height:1;color:#ffffff10;font-weight:800;pointer-events:none}.opening span{font-size:12px;color:#aaddff;font-weight:800;letter-spacing:.05em}.opening h3{position:relative;font-size:clamp(21px,2.5vw,29px);line-height:1.4;margin:9px 0;max-width:590px;letter-spacing:-.035em}.opening p{position:relative;color:#d6e8f7;font-size:14px;line-height:1.7;max-width:580px;margin:0 0 17px}.opening button{position:relative;background:#fff;color:#15538c;border:0;border-radius:8px;padding:9px 13px;font-size:13px;font-weight:700}.opening button:hover{background:#dff4ff}.conceptReveal{border-top:1px solid #e3ebf3;margin:17px 0 0;padding-top:16px}.conceptReveal h3{font-size:15px;margin:0 0 8px;color:#245b8f}.conceptReveal .conceptText{margin-bottom:16px}.storyBox{margin-bottom:0}@media(max-width:620px){.opening{padding:18px}.opening h3{font-size:22px}}
.predictionQuick{display:flex;gap:7px;align-items:center;flex-wrap:wrap;margin:9px 0 2px}.predictionQuick span{font-size:12px;color:#58708c;margin-right:5px}.predictionQuick button{border:1px solid #cbddef;border-radius:16px;background:#fff;color:#416586;padding:6px 10px;font-size:12px}.predictionQuick button:hover,.predictionQuick button.chosen{background:#ddecff;border-color:#4b85c6;color:#174b89;font-weight:700}.predictionFeedback{font-size:13px;color:#226e61;min-height:0;margin:6px 0 0;line-height:1.5}
.kitGallery{margin-top:15px;padding:16px;background:#eef5fc;border:1px solid #d4e4f3;border-radius:12px}.kitHeader{display:flex;align-items:end;justify-content:space-between;gap:12px;margin-bottom:10px}.kitHeader span{font-size:11px;color:#63809e}.kitHeader>div span{font-weight:800;color:#286aa1}.kitHeader h3{font-size:16px;margin:3px 0 0}.kitCards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:9px}.kitCards button{min-width:0;overflow:hidden;text-align:left;border:2px solid transparent;background:#fff;border-radius:10px;padding:0 0 10px;color:#243b59;box-shadow:0 3px 10px #193d6014}.kitCards button:hover,.kitCards button.selected{border-color:#4b8dce;transform:translateY(-2px)}.kitCards img{width:100%;height:100px;object-fit:cover;display:block}.kitCards button:nth-child(2) img{object-position:center 60%}.kitCards strong,.kitCards small{display:block;padding:0 10px}.kitCards strong{font-size:13px;margin-top:8px}.kitCards small{font-size:11px;color:#6c829b;margin-top:3px}.kitDetail{font-size:12px;color:#435e7d;margin-top:10px;line-height:1.5;min-height:18px}.liveInstrument{display:flex;align-items:center;gap:16px;background:#102941;border:1px solid #315b77;border-radius:13px;color:white;margin-top:12px;padding:17px}.instrumentGlyph{width:66px;height:66px;border-radius:50%;background:#204763;display:grid;place-items:center;font-size:38px;color:#6fd9cc;flex:none;box-shadow:inset 0 0 15px #071b31}.instrumentGlyph.energized{animation:ccInstrumentPulse 1.4s ease-in-out infinite alternate}.instrumentScreen{min-width:0;flex:1}.instrumentScreen>span{font-size:11px;letter-spacing:.07em;color:#93c7df}.instrumentScreen strong{display:block;font:700 30px/1.3 ui-monospace,monospace;color:#a7f0df;margin:3px 0}.instrumentScreen small{display:block;color:#a4bdcf;font-size:11px;line-height:1.4;margin-top:7px}.instrumentTrack{height:7px;border-radius:9px;background:#315570;overflow:hidden}.instrumentTrack span{display:block;height:100%;width:0;background:linear-gradient(90deg,#53a7ff,#76e1bd);transition:width .25s}.sourceCard a{font-size:13px;font-weight:700;color:#2761b9}.sourceCard small{display:block;color:#7c8da4;font-size:11px;margin-top:9px}footer details{margin-bottom:12px}footer a{color:#376fab}.circuitWire{stroke-dasharray:7 5;stroke-dashoffset:0}.running .circuitWire{animation:ccFlow 1s linear infinite}@keyframes ccFlow{to{stroke-dashoffset:-24}}@keyframes ccInstrumentPulse{to{box-shadow:0 0 23px #52debc88,inset 0 0 15px #071b31}}@media(prefers-reduced-motion:reduce){.running .circuitWire,.instrumentGlyph.energized{animation:none}}@media(max-width:620px){.kitCards img{height:73px}.kitCards small{display:none}.kitHeader>span{display:none}.liveInstrument{padding:12px}.instrumentGlyph{width:48px;height:48px;font-size:27px}.instrumentScreen strong{font-size:22px}}
.presetBar{display:flex;align-items:center;flex-wrap:wrap;gap:8px;margin:13px 0 0;padding:11px 13px;background:#f5f1ff;border:1px solid #ded5fa;border-radius:10px}.presetBar span{font-size:12px;color:#7052a5;font-weight:800;margin-right:3px}.presetBar button{border:1px solid #c9b7e9;border-radius:7px;background:#fff;color:#59418a;padding:7px 10px;font-size:12px}.presetBar button:hover{background:#e9defb}.presetBar small{color:#8779a1;font-size:11px;margin-left:auto}
.sceneCard{background:linear-gradient(115deg,#e9f6ff,#f3fbf7);border:1px solid #cce3ee;border-radius:13px;padding:15px;margin-top:15px;display:grid;grid-template-columns:minmax(180px,.48fr) minmax(0,1fr);align-items:center;gap:12px}.sceneCard>div span{display:block;color:#1687a4;letter-spacing:.12em;font-size:10px;font-weight:800}.sceneCard strong{display:block;font-size:17px;letter-spacing:-.03em;margin:5px 0}.sceneCard p{color:#4e7186;font-size:12px;line-height:1.6;margin:0}.sceneCard svg{width:100%;height:155px;background:#f7fbff;border-radius:9px}@media(max-width:720px){.sceneCard{grid-template-columns:1fr}.sceneCard svg{height:135px}}
.conceptFigure{margin:16px 0 0;padding:17px;background:#f5fafb;border:1px solid #cbdfe7;border-radius:16px}.conceptFigure figcaption{display:flex;flex-direction:column;gap:5px;line-height:1.55}.conceptFigure figcaption strong{font-size:15px;color:#22546b}.conceptFigure figcaption span{font-size:12px;color:#597687}.conceptFigure svg{width:100%;height:auto;max-height:265px;display:block;margin-top:10px}

/* Plain-language sequence leads into the formal model. */
.opening{padding:15px 19px;margin-bottom:14px;background:linear-gradient(120deg,#194b6b,#247b91)}.opening:after{font-size:105px;top:-10px}.opening h3{font-size:clamp(20px,2vw,25px);margin:5px 0}.opening p{margin:0 0 10px}.easyGuide{display:grid;grid-template-columns:1fr 1fr;gap:11px;margin-bottom:15px}.easyGuide>div{padding:16px 17px;border-radius:12px;border:1px solid #d8e7eb;background:#f5fafb}.easyGuide span{font-size:14px;color:#0a7080;font-weight:850}.easyGuide p{font-size:16px;line-height:1.75;margin:7px 0 0;color:#234354}.easyGuide .easyWorked{grid-column:1/-1;background:#ecf7f2;border-color:#b6ded2}.easyGuide ol{margin:10px 0 0;padding-left:24px;display:grid;gap:7px;font-size:16px;line-height:1.7}.easyGuide>p{grid-column:1/-1;font-size:15px;line-height:1.7;margin:0;padding:11px 15px;border-radius:10px}.easyTerms{background:#eaf1ff;color:#264e79}.easyTry{background:#eef9f0;color:#245a45}.easyCaution{background:#fff7e8;color:#795624}.formulaRow strong{font-size:21px}.formulaRow small{font-size:14px}.storyBox{margin:12px 0 16px}.storyBox p{font-size:16px}@media(max-width:700px){.easyGuide{grid-template-columns:1fr}.easyGuide .easyWorked{grid-column:auto}}