:root{--ink:#183436;--muted:#587172;--paper:#f7f6f0;--white:#fff;--teal:#1d7772;--teal2:#d9efea;--coral:#ec775c;--coral2:#fae4dc;--gold:#e7b94f;--gold2:#fbf0ce;--blue:#5379a5;--blue2:#e4edf7;--line:#dbe4de;--shadow:0 12px 34px #18343612;--radius:21px}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif;line-height:1.55}button,select,input{font:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible,select:focus-visible,input:focus-visible{outline:3px solid var(--gold);outline-offset:3px}.topbar{position:sticky;top:0;z-index:20;background:#f7f6f0ee;backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}.topinner{max-width:1240px;margin:auto;padding:11px 24px;display:flex;align-items:center;gap:20px}.brand{display:flex;align-items:center;gap:10px;min-width:220px;color:var(--ink);text-decoration:none}.brandmark{width:42px;height:42px;border-radius:14px;background:var(--teal);display:grid;place-items:center;color:#fff;font-size:22px}.brand strong{display:block;font-size:13px;letter-spacing:.04em}.brand small{display:block;color:var(--muted);font-size:11px}.nav{display:flex;gap:4px;flex:1;justify-content:center}.nav button{border:0;background:transparent;color:var(--muted);padding:10px 12px;border-radius:11px;font-size:12px;font-weight:800}.nav button:hover,.nav button.active{background:var(--teal2);color:var(--teal)}.top-progress{min-width:140px;font-size:11px;color:var(--muted)}.progressrow{display:flex;justify-content:space-between;margin-bottom:4px}.progressline{height:7px;background:#e3e9e3;border-radius:9px;overflow:hidden}.progressline span{display:block;height:100%;width:0;background:var(--coral);border-radius:9px;transition:width .3s}.menu-toggle{display:none;border:1px solid var(--line);background:white;border-radius:10px;padding:7px 10px}.main{max-width:1240px;padding:28px 24px 68px;margin:auto}.view{display:none}.view.active{display:block}.hero{position:relative;overflow:hidden;border-radius:30px;background:var(--ink);color:white;padding:46px;min-height:330px;display:grid;grid-template-columns:1.1fr .9fr;align-items:center;gap:20px;box-shadow:var(--shadow)}.hero:after{content:"";position:absolute;width:280px;height:280px;border-radius:50%;background:#ffffff0b;right:-30px;top:-80px}.eyebrow{text-transform:uppercase;letter-spacing:.12em;font-size:10px;font-weight:900;color:var(--gold)}.tealtext{color:var(--teal)}h1,h2,h3,h4,p{margin-top:0}.hero h1{font-size:clamp(34px,5vw,57px);line-height:1.02;letter-spacing:-.045em;max-width:650px;margin:14px 0 18px}.hero p{max-width:580px;color:#d6e4df;font-size:15px}.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px}.actions.center{justify-content:center}.btn{border:0;border-radius:12px;padding:11px 16px;font-weight:850;background:var(--teal);color:white;transition:transform .15s,filter .15s;display:inline-flex;align-items:center;justify-content:center;gap:7px}.btn:hover{transform:translateY(-2px);filter:brightness(1.07)}.btn.coral{background:var(--coral)}.btn.light{background:white;color:var(--ink)}.btn.outline{border:1px solid var(--line);background:transparent;color:var(--ink)}.btn.small{padding:8px 11px;font-size:11px}.btn:disabled{opacity:.5;cursor:not-allowed;transform:none}.hero-art{position:relative;z-index:1;min-height:230px;display:grid;place-items:center}.atom{width:195px;height:195px;border-radius:50%;background:#ffffff0c;border:1px solid #ffffff22;display:grid;place-items:center;position:relative}.atom b{width:50px;height:50px;background:var(--coral);border-radius:50%;display:grid;place-items:center;font-size:22px;box-shadow:0 0 0 13px #ec775c20}.orbit{position:absolute;width:175px;height:66px;border:2px solid var(--gold);border-radius:50%}.orbit.o2{transform:rotate(60deg);border-color:#71c3b7}.orbit.o3{transform:rotate(-60deg);border-color:#d19ad6}.electron{position:absolute;width:12px;height:12px;background:white;border-radius:50%;top:22px;right:37px}.float-tag{position:absolute;background:white;color:var(--ink);border-radius:10px;padding:7px 11px;font-size:10px;font-weight:900;box-shadow:var(--shadow)}.float-tag.one{left:0;top:28px}.float-tag.two{right:0;bottom:20px}.sectionhead{display:flex;justify-content:space-between;align-items:end;gap:18px;margin:36px 0 15px}.sectionhead h2{font-size:26px;letter-spacing:-.03em;margin-bottom:3px}.sectionhead p{color:var(--muted);margin:0}.grid{display:grid;gap:15px}.grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}.grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}.card{background:var(--white);border:1px solid var(--line);border-radius:var(--radius);padding:21px;box-shadow:var(--shadow)}.topic{min-height:205px;transition:transform .2s,border-color .2s}.topic:hover{transform:translateY(-3px);border-color:#9ccac1}.icon{font-size:26px;width:50px;height:50px;display:grid;place-items:center;border-radius:15px;background:var(--teal2);margin-bottom:15px}.coralcard .icon{background:var(--coral2)}.topic h3{font-size:19px;margin:11px 0 7px}.topic p,.card p{color:var(--muted);font-size:13px}.tag{display:inline-flex;align-items:center;border-radius:40px;padding:5px 10px;font-size:10px;font-weight:900;background:var(--gold2);color:#755600}.tag.teal{background:var(--teal2);color:var(--teal)}.tag.coral{background:var(--coral2);color:#9a402b}.daily{display:grid;grid-template-columns:1fr auto;gap:20px;align-items:center;background:var(--gold2);border:1px solid #f0dfac;border-radius:21px;padding:22px;margin-top:17px}.daily h3{margin:10px 0 2px}.daily p{color:#665625;margin:0}.stats{display:flex;gap:10px}.stats div,.progress-cards>div{background:#ffffffbd;padding:11px 15px;border-radius:14px;text-align:center;min-width:75px}.stats b,.progress-cards b{display:block;font-size:22px}.stats small,.progress-cards small{font-size:10px;text-transform:uppercase;font-weight:900;color:var(--muted)}.page-title{display:flex;justify-content:space-between;align-items:end;gap:20px;margin-bottom:22px}.page-title h1{font-size:clamp(28px,4vw,41px);letter-spacing:-.04em;line-height:1.1;margin:4px 0 7px}.page-title p{color:var(--muted);margin:0;max-width:760px}.breadcrumbs{font-size:11px;color:var(--muted);margin-bottom:8px}.lesson-layout{display:grid;grid-template-columns:260px 1fr;gap:20px;align-items:start}.lesson-list{position:sticky;top:92px}.lesson-list>.card{padding:11px}.lesson-filter{display:flex;gap:7px;margin-bottom:9px}.lesson-filter button{flex:1;border:0;border-radius:9px;padding:8px;background:#f1f3ef;color:var(--muted);font-size:11px;font-weight:900}.lesson-filter button.active{background:var(--teal);color:white}.lesson-link{width:100%;border:0;background:transparent;border-radius:10px;text-align:left;padding:9px;display:flex;gap:9px;align-items:flex-start;color:var(--ink);font-weight:750;font-size:11px}.lesson-link:hover,.lesson-link.active{background:var(--teal2);color:var(--teal)}.lesson-link .num{width:22px;height:22px;display:grid;place-items:center;border-radius:7px;background:#edf1ed;flex:none;font-size:10px}.lesson-link.done .num{background:var(--teal);color:white}.article{background:white;border:1px solid var(--line);border-radius:23px;padding:clamp(20px,4vw,38px);box-shadow:var(--shadow)}.article h2{font-size:29px;letter-spacing:-.03em;line-height:1.1;margin:10px 0}.article h3{font-size:19px;margin:25px 0 9px}.article h4{margin:15px 0 6px}.article p,.article li{color:#425b5b}.article p{margin-bottom:12px}.article li{margin:6px 0}.article ul,.article ol{padding-left:22px}.article .lead{font-size:16px;color:var(--ink)}.callout{border-left:4px solid var(--gold);background:#fbf5e4;padding:13px 15px;border-radius:0 13px 13px 0;margin:16px 0;color:#5d4b1b}.callout.teal{border-color:var(--teal);background:#eaf5f1;color:#27514c}.callout.coral{border-color:var(--coral);background:#fcf0ec;color:#784330}.level-ladder{display:grid;grid-template-columns:repeat(5,1fr);gap:7px;margin:17px 0}.level{padding:12px 6px;border-radius:14px;text-align:center;background:var(--teal2);font-size:10px;font-weight:900}.level:nth-child(2){background:var(--gold2)}.level:nth-child(3){background:var(--coral2)}.level:nth-child(4){background:var(--blue2)}.level:nth-child(5){background:#e4f1df}.level span{display:block;font-size:22px;margin-bottom:4px}.diagram{background:#f4f8f5;border:1px solid var(--line);border-radius:18px;padding:18px;margin:18px 0}.cell-layout{display:grid;grid-template-columns:minmax(220px,.9fr) 1.1fr;gap:16px;align-items:center}.cell-svg{width:100%;max-width:350px;margin:auto}.cell-hotspot{cursor:pointer;transition:filter .15s}.cell-hotspot:hover,.cell-hotspot:focus{filter:brightness(1.15);stroke:#183436;stroke-width:4}.hotspot-list{display:flex;flex-wrap:wrap;gap:6px;margin-top:10px}.hotspot-list button{background:white;border:1px solid var(--line);border-radius:30px;padding:6px 9px;color:var(--ink);font-size:10px;font-weight:800}.hotspot-list button.active{background:var(--teal);color:white}.detail-box{background:white;border:1px solid var(--line);border-radius:13px;padding:14px;min-height:85px}.detail-box h4{margin:0 0 4px}.detail-box p{font-size:12px;margin:0}.anatomy-map{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin:12px 0}.map-btn{background:white;border:1px solid var(--line);padding:12px;border-radius:13px;text-align:left;color:var(--ink);font-weight:850;font-size:12px}.map-btn:hover,.map-btn.active{border-color:var(--teal);background:var(--teal2)}.zonegrid{display:grid;grid-template-columns:repeat(3,1fr);gap:4px;max-width:420px;margin:13px auto}.zonegrid button{min-height:54px;background:#fff8e8;border:1px solid #eddba9;color:#654d15;border-radius:7px;font-size:10px;font-weight:850}.zonegrid button:hover,.zonegrid button.active{background:var(--gold);color:var(--ink)}.plane-svg{width:100%;max-height:270px}.motion-demo{background:#f3f6f2;border:1px solid var(--line);border-radius:15px;padding:16px;margin:17px 0}.motion-demo input{width:100%;accent-color:var(--coral)}.arm{width:140px;height:105px;margin:8px auto;position:relative}.arm .upper{position:absolute;width:15px;height:69px;background:#e5b598;left:63px;top:5px;border-radius:10px;transform-origin:bottom center}.arm .fore{position:absolute;width:14px;height:63px;background:#efc5a4;left:63px;top:63px;border-radius:10px;transform-origin:top center}.arm .joint{position:absolute;width:22px;height:22px;background:var(--coral);border-radius:50%;left:59px;top:56px;z-index:2}.quiz-shell{max-width:860px;margin:auto}.quiz-controls{display:flex;gap:12px;flex-wrap:wrap;align-items:end;margin:18px 0}.quiz-controls label{flex:1;min-width:180px;font-size:12px;font-weight:800}.quiz-controls select{display:block;width:100%;margin-top:5px;border:1px solid var(--line);background:white;border-radius:10px;padding:10px;color:var(--ink)}.quiz-progress{display:flex;justify-content:space-between;color:var(--muted);font-size:11px;font-weight:850;margin:12px 0}.question-card{background:white;border:1px solid var(--line);border-radius:23px;padding:clamp(20px,4vw,34px);box-shadow:var(--shadow)}.question-card h2{font-size:23px;line-height:1.3}.answers{display:grid;gap:9px;margin:18px 0}.answer{border:1px solid var(--line);background:white;border-radius:13px;padding:12px 14px;text-align:left;font-weight:750;color:var(--ink);display:flex;gap:10px;align-items:center}.answer .letter{width:25px;height:25px;border-radius:8px;background:#f0f3f0;display:grid;place-items:center;color:var(--muted);font-size:11px;flex:none}.answer:hover:not(:disabled){border-color:var(--teal);background:#f3faf7}.answer.correct{border-color:#57a17e;background:#e7f5ed}.answer.wrong{border-color:var(--coral);background:#fff0ec}.feedback{padding:13px;border-radius:13px;background:#f2f6f1;margin:12px 0;font-size:13px}.feedback.good{background:#e7f5ed}.feedback.bad{background:#fff0ec}.score-ring{width:125px;height:125px;border-radius:50%;background:var(--teal2);display:grid;place-items:center;margin:10px auto 18px;text-align:center}.score-ring b{font-size:32px;display:block}.score-ring small{font-size:9px;font-weight:900;text-transform:uppercase}.game-tabs{display:flex;gap:8px;flex-wrap:wrap;margin:14px 0}.game-tabs button{border:1px solid var(--line);background:white;color:var(--muted);padding:8px 13px;border-radius:30px;font-weight:850;font-size:11px}.game-tabs button.active{background:var(--ink);color:white;border-color:var(--ink)}.game-panel{display:none}.game-panel.active{display:block}.order-board{display:grid;grid-template-columns:1fr 1fr;gap:17px}.tilebox{min-height:165px;background:#f3f6f2;border:2px dashed #c9d8d0;border-radius:16px;padding:12px;display:flex;flex-direction:column;gap:7px}.tile{border:1px solid var(--line);background:white;border-radius:11px;padding:10px;font-weight:850;text-align:left;color:var(--ink)}.tile:hover{border-color:var(--teal)}.match-grid{display:grid;grid-template-columns:1fr 1fr;gap:9px}.match-item{background:white;border:1px solid var(--line);border-radius:12px;padding:12px;text-align:left;color:var(--ink);font-weight:750;min-height:58px;font-size:12px}.match-item.selected{background:var(--gold2);border-color:var(--gold)}.match-item.matched{background:#e5f5ec;border-color:#76b691;opacity:.72}.flashcard{width:100%;min-height:220px;border:0;background:var(--ink);color:white;border-radius:22px;padding:25px;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;margin:14px 0;cursor:pointer}.flashcard h3{font-size:23px;max-width:620px;margin:12px 0}.flashcard p{color:#d5e2dc;max-width:600px}.flashcard small{color:#c9d8d0}.progress-cards{display:grid;grid-template-columns:repeat(4,1fr);gap:11px}.progress-cards>div{background:white;border:1px solid var(--line);border-radius:16px;padding:17px}.progress-cards b{font-size:27px}.progress-cards small{font-size:10px;text-transform:uppercase;font-weight:900;color:var(--muted)}.table-wrap{overflow:auto}.result-table{width:100%;border-collapse:collapse;background:white;border-radius:15px;overflow:hidden}.result-table th,.result-table td{padding:11px 13px;border-bottom:1px solid var(--line);text-align:left;font-size:12px}.result-table th{background:#edf4ef;color:var(--muted);font-size:10px;text-transform:uppercase}.empty{text-align:center;padding:30px;color:var(--muted)}.bigemoji{font-size:35px}.muted{color:var(--muted)}.smalltext{font-size:11px;color:var(--muted)}.pill-row{display:flex;gap:7px;flex-wrap:wrap;margin-top:11px}.footer{border-top:1px solid var(--line);padding:21px 24px;color:var(--muted);font-size:11px}.footer>div{max-width:1240px;margin:auto;display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap}.toast{position:fixed;bottom:20px;right:20px;background:var(--ink);color:white;padding:11px 15px;border-radius:12px;box-shadow:var(--shadow);z-index:40;opacity:0;transform:translateY(12px);transition:.2s;pointer-events:none}.toast.show{opacity:1;transform:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
@media(max-width:900px){.topinner{gap:9px}.brand{min-width:170px}.nav button{padding:9px;font-size:11px}.top-progress{min-width:105px}.lesson-layout{grid-template-columns:220px 1fr}.cell-layout{grid-template-columns:1fr}.cell-svg{max-height:270px}.progress-cards{grid-template-columns:repeat(2,1fr)}}
@media(max-width:650px){.topinner{padding:9px 13px;justify-content:space-between}.menu-toggle{display:block}.nav{display:none;position:absolute;top:62px;left:10px;right:10px;background:white;border:1px solid var(--line);border-radius:15px;padding:8px;box-shadow:var(--shadow);flex-direction:column}.nav.open{display:flex}.nav button{text-align:left;padding:11px}.top-progress{display:none}.main{padding:17px 13px 48px}.hero{grid-template-columns:1fr;padding:27px 21px;min-height:0}.hero h1{font-size:41px}.hero-art{min-height:190px}.atom{width:165px;height:165px}.orbit{width:148px;height:57px}.float-tag.one{left:2px;top:10px}.float-tag.two{right:2px;bottom:5px}.grid.two,.grid.three{grid-template-columns:1fr}.sectionhead{align-items:start;flex-direction:column}.daily{grid-template-columns:1fr}.stats{justify-content:flex-start}.lesson-layout{grid-template-columns:1fr}.lesson-list{position:static}.lesson-list #lessonList{display:grid;grid-template-columns:1fr 1fr;max-height:260px;overflow:auto}.article{padding:20px 16px}.article h2{font-size:25px}.level-ladder{grid-template-columns:1fr}.level{display:flex;align-items:center;gap:10px;text-align:left;padding:9px}.level span{margin:0}.page-title{flex-direction:column;align-items:start}.quiz-controls{align-items:stretch;flex-direction:column}.quiz-controls label,.quiz-controls .btn{width:100%}.order-board,.match-grid{grid-template-columns:1fr}.progress-cards{grid-template-columns:1fr 1fr}.anatomy-map{grid-template-columns:1fr 1fr}.footer>div{flex-direction:column}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
/* Interactive study controls */
.lesson-item{width:100%;display:flex;gap:10px;align-items:center;text-align:left;padding:12px;border:0;border-radius:12px;background:transparent;color:var(--ink)}.lesson-item:hover,.lesson-item.active{background:var(--teal2)}.lesson-item small{display:block;color:var(--muted);font-size:11px}.lesson-item i{margin-left:auto;color:var(--teal)}.lesson-actions,.lesson-nav{display:flex;gap:10px;flex-wrap:wrap;margin:22px 0 10px}.lesson-nav{justify-content:space-between;border-top:1px solid var(--line);padding-top:16px}.quiz-meta{display:flex;justify-content:space-between;color:var(--muted);margin:18px 0 8px}.quiz-progress{height:7px;background:var(--line);border-radius:9px;overflow:hidden;margin-bottom:16px}.quiz-progress i{display:block;height:100%;background:var(--teal)}.question-card,.result-card{background:#fff;border:1px solid var(--line);border-radius:20px;padding:clamp(18px,4vw,32px);box-shadow:var(--shadow)}.question-card h2{font-size:clamp(21px,3vw,30px)}.answers{display:grid;gap:10px;margin:20px 0}.answer{border:1px solid var(--line);border-radius:12px;background:#fff;color:var(--ink);padding:13px 15px;text-align:left}.answer:hover:not(:disabled){border-color:var(--teal);background:#f2faf7}.answer.correct,.match-tile.correct{border-color:#2d986d;background:#e2f5eb;color:#145c3e}.answer.wrong,.match-tile.wrong{border-color:#dc7159;background:#fff0ec;color:#803c2d}.explanation{padding:12px 0;color:var(--muted)}.hidden{display:none!important}.result-card{text-align:center;margin:22px 0}.big-emoji{font-size:58px}.chip,.match-tile{border:1px solid var(--line);background:#fff;border-radius:12px;padding:12px;color:var(--ink)}.chip:disabled,.match-tile:disabled{opacity:1}.orderPool,.order-board,#orderPool,#orderAnswer,.match-grid,#matchGrid{display:flex;flex-wrap:wrap;gap:9px;margin:14px 0}.sequence-item{background:var(--teal2);padding:9px 12px;border-radius:10px}.match-tile{min-height:74px;flex:1 1 180px;text-align:left}.match-tile.selected{outline:3px solid var(--gold)}.feedback{min-height:28px;color:var(--muted);font-weight:700}.feedback.good{color:#18794e}.cell-hotspot{cursor:pointer;transition:filter .15s,stroke-width .15s}.cell-hotspot:hover,.cell-hotspot.selected{filter:brightness(1.12);stroke-width:9}.detail-box{background:var(--teal2);border-radius:14px;padding:14px;margin-top:12px}.detail-box h4{margin:0 0 5px}.detail-box p{margin:0}.progress-row{display:flex;justify-content:space-between;gap:15px;padding:11px 0;border-bottom:1px solid var(--line)}
.route-section{margin-top:38px}.study-route{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.route-step{width:100%;display:flex;align-items:center;gap:12px;padding:14px;border:1px solid var(--line);border-radius:14px;background:#fff;color:var(--ink);text-align:left}.route-step:hover{border-color:var(--teal);transform:translateY(-1px)}.route-step.done{background:#edf8f3;border-color:#c7e6d7}.route-step small{display:block;color:var(--muted);font-size:12px}.route-number{display:grid;place-items:center;flex:0 0 38px;height:38px;border-radius:12px;background:var(--teal2);font-weight:900;color:var(--teal)}.route-status{margin-left:auto;font-size:12px;white-space:nowrap;color:var(--teal);font-weight:800}.progress-link{width:100%;font:inherit;text-align:left;background:#fff;border:0;cursor:pointer}.progress-link:hover{background:var(--teal2)}
@media(max-width:700px){.study-route{grid-template-columns:1fr}.route-status{font-size:11px}}
.footer-nav{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}.footer-nav button{border:1px solid var(--line);border-radius:9px;background:#fff;padding:7px 11px;color:var(--ink)}.footer-nav button:hover{background:var(--teal2)}.brand strong{font-size:11px;letter-spacing:.01em;white-space:nowrap}