*{box-sizing:border-box;margin:0;padding:0}
:root{--navy:#071d33;--navy-2:#173b5b;--ink:#17283b;--muted:#627589;--silver:#cbd5df;--silver-2:#e8edf2;--paper:#fff;--soft:#f5f7f9;--blue:#315f89;--green:#247356;--orange:#a85e26;--red:#a33b49;--shadow:0 28px 70px -54px rgba(7,29,51,.78)}
html{scroll-behavior:smooth}
body{min-height:100vh;font-family:"Pretendard","Lexend",-apple-system,BlinkMacSystemFont,sans-serif;background:linear-gradient(145deg,#fff 0%,#f4f7f9 55%,#e7edf2 100%);color:var(--ink);line-height:1.65}
a{color:inherit;text-decoration:none}
button{font:inherit}
.lesson-topbar{position:sticky;top:0;z-index:30;border-bottom:1px solid rgba(176,190,203,.72);background:rgba(255,255,255,.9);backdrop-filter:blur(18px)}
.lesson-topbar-inner{width:min(1180px,calc(100% - 36px));min-height:66px;margin:auto;display:flex;align-items:center;justify-content:space-between;gap:18px}
.lesson-brand{display:flex;align-items:center;gap:12px;color:var(--navy);font-weight:900;letter-spacing:-.4px}
.lesson-brand img{width:38px;height:38px;border:1px solid #c7d1db;border-radius:10px;background:#fff}
.lesson-brand small{display:block;color:#718397;font-family:"Lexend",sans-serif;font-size:9px;font-weight:700;letter-spacing:2px;text-transform:uppercase}
.top-actions{display:flex;gap:7px}
.top-link{display:inline-flex;align-items:center;justify-content:center;min-height:36px;padding:8px 13px;border:1px solid #b9c5d0;border-radius:999px;background:#fff;color:var(--navy);font-size:11px;font-weight:850;white-space:nowrap}
.top-link.primary{border-color:var(--navy);background:var(--navy);color:#fff}
.lesson-hero{width:min(1180px,calc(100% - 36px));margin:0 auto;padding:72px 0 48px;display:grid;grid-template-columns:minmax(0,.95fr) minmax(400px,1.05fr);gap:46px;align-items:center}
.lesson-eyebrow{display:flex;align-items:center;gap:12px;margin-bottom:18px;color:var(--blue);font-family:"Lexend",sans-serif;font-size:11px;font-weight:800;letter-spacing:2px;text-transform:uppercase}
.lesson-no{display:grid;place-items:center;width:38px;height:38px;border-radius:11px;background:var(--navy);color:#fff;letter-spacing:0}
.lesson-hero h1{color:var(--navy);font-size:clamp(45px,6.2vw,78px);font-weight:900;line-height:1.02;letter-spacing:-3.8px;word-break:keep-all}
.hero-lead{margin-top:22px;max-width:610px;color:#52677b;font-size:17px;line-height:1.85;word-break:keep-all}
.hero-tags{display:flex;flex-wrap:wrap;gap:8px;margin-top:26px}
.hero-tag{padding:8px 12px;border:1px solid #c2cdd7;border-radius:999px;background:rgba(255,255,255,.76);color:var(--navy-2);font-size:11px;font-weight:800}
.hero-board{position:relative;min-height:360px;padding:30px;border:1px solid #c8d3dd;border-radius:28px;background:rgba(255,255,255,.86);box-shadow:var(--shadow);overflow:hidden}
.hero-board::before{content:"";position:absolute;inset:0;background:linear-gradient(120deg,transparent 0 47%,rgba(210,220,229,.35) 47% 48%,transparent 48%)}
.hero-board>*{position:relative}
.board-kicker{color:#7d8d9d;font-family:"Lexend",sans-serif;font-size:9px;font-weight:800;letter-spacing:2px;text-transform:uppercase}
.board-title{margin-top:12px;color:var(--navy);font-size:28px;font-weight:900;line-height:1.2;letter-spacing:-1px}
.board-flow{display:flex;align-items:center;gap:8px;margin-top:30px}
.board-node{flex:1;min-height:88px;padding:15px 10px;border:1px solid #cbd5de;border-radius:15px;background:#fff;text-align:center;box-shadow:0 16px 34px -31px rgba(7,29,51,.8)}
.board-node b{display:block;color:var(--blue);font-family:"Lexend",sans-serif;font-size:10px;letter-spacing:1px}
.board-node span{display:block;margin-top:7px;color:var(--navy);font-size:13px;font-weight:850;line-height:1.35;word-break:keep-all}
.board-arrow{color:#8fa0b0;font-weight:900}
.board-result{margin-top:16px;padding:13px 15px;border-radius:12px;background:var(--navy);color:#d8e2eb;font-size:12px;font-weight:700}
.lesson-layout{width:min(1180px,calc(100% - 36px));margin:0 auto 80px;display:grid;grid-template-columns:224px minmax(0,1fr);gap:30px;align-items:start}
.lesson-nav{position:sticky;top:88px;padding:17px;border:1px solid #cbd5de;border-radius:20px;background:rgba(255,255,255,.85);box-shadow:var(--shadow)}
.nav-label{margin:0 7px 11px;color:#8190a0;font-family:"Lexend",sans-serif;font-size:9px;font-weight:800;letter-spacing:2px;text-transform:uppercase}
.lesson-nav a{display:grid;grid-template-columns:27px 1fr;gap:8px;align-items:center;padding:10px 8px;border-radius:10px;color:#586d81;font-size:12px;font-weight:750}
.lesson-nav a:hover{background:#edf2f6;color:var(--navy)}
.lesson-nav b{color:#9cabba;font-family:"Lexend",sans-serif;font-size:9px}
.lesson-main{display:grid;gap:18px}
.lesson-section{overflow:hidden;border:1px solid #cbd5de;border-radius:24px;background:rgba(255,255,255,.94);box-shadow:var(--shadow)}
.section-grid{display:grid;grid-template-columns:minmax(310px,.9fr) minmax(0,1.1fr);min-height:455px}
.section-copy{padding:38px 34px;display:flex;flex-direction:column;justify-content:center}
.section-kicker{margin-bottom:14px;color:#8090a1;font-family:"Lexend",sans-serif;font-size:9px;font-weight:800;letter-spacing:2px;text-transform:uppercase}
.section-copy h2{color:var(--navy);font-size:clamp(27px,3vw,42px);font-weight:900;line-height:1.13;letter-spacing:-1.7px;word-break:keep-all}
.section-copy>p{margin-top:16px;color:#5b6f82;font-size:15px;line-height:1.82;word-break:keep-all}
.task-list{display:grid;gap:9px;margin-top:20px}
.task-list li{position:relative;list-style:none;min-height:23px;padding-left:32px;color:#40566c;font-size:13px;font-weight:650;line-height:1.6;word-break:keep-all}
.task-list li::before{content:attr(data-num);position:absolute;left:0;top:1px;display:grid;place-items:center;width:22px;height:22px;border-radius:50%;background:#e9eff4;color:var(--blue);font-family:"Lexend",sans-serif;font-size:8px;font-weight:900}
.checkpoint{margin-top:19px;padding:13px 15px;border-left:3px solid var(--blue);background:#eff4f8;color:#4f667b;font-size:12px;line-height:1.65;word-break:keep-all}
.visual{display:flex;align-items:center;justify-content:center;min-width:0;padding:26px;background:linear-gradient(145deg,#f1f5f8,#e2e9ef)}
.visual-card{width:100%;max-width:570px;padding:24px;border:1px solid #bfcbd6;border-radius:18px;background:#fff;box-shadow:0 22px 48px -39px rgba(7,29,51,.8)}
.visual-label{color:#8190a0;font-family:"Lexend",sans-serif;font-size:8px;font-weight:800;letter-spacing:1.8px;text-transform:uppercase}
.window-map{display:grid;grid-template-columns:1fr 1.6fr 1fr;grid-template-rows:160px 95px;gap:8px;margin-top:16px}
.window-box{display:flex;align-items:center;justify-content:center;padding:12px;border:1px solid #cbd5de;border-radius:10px;background:#f8fafb;color:var(--navy);font-size:12px;font-weight:850;text-align:center}
.window-box.scene{grid-column:2;grid-row:1;background:#e8eef4}.window-box.hierarchy{grid-column:1;grid-row:1}.window-box.inspector{grid-column:3;grid-row:1}.window-box.project{grid-column:1/4;grid-row:2}
.component-stack{display:grid;gap:9px;margin-top:17px}.component{display:grid;grid-template-columns:36px 1fr auto;gap:11px;align-items:center;padding:12px;border:1px solid #d0d9e1;border-radius:11px;background:#fafbfd}.component i{display:grid;place-items:center;width:34px;height:34px;border-radius:9px;background:var(--navy);color:#fff;font-style:normal;font-size:10px}.component b{color:var(--navy);font-size:13px}.component small{color:#8090a0;font-size:10px}.component em{color:var(--green);font-size:10px;font-style:normal;font-weight:850}
.axis-stage{position:relative;height:270px;margin-top:16px;border:1px solid #d2dbe3;border-radius:14px;background:radial-gradient(circle at center,#fff,#eef3f7)}.axis-object{position:absolute;left:50%;top:50%;width:74px;height:74px;transform:translate(-50%,-50%) rotate(10deg);border:2px solid #173b5b;background:linear-gradient(145deg,#fff,#bfcbd7);box-shadow:12px 14px 24px -18px #071d33}.axis{position:absolute;left:50%;top:50%;height:3px;transform-origin:left center}.axis::after{content:"";position:absolute;right:-2px;top:-4px;border-left:8px solid currentColor;border-top:5px solid transparent;border-bottom:5px solid transparent}.axis.x{width:125px;background:#c34556;color:#c34556;transform:rotate(0)}.axis.y{width:110px;background:#2a8462;color:#2a8462;transform:rotate(-90deg)}.axis.z{width:95px;background:#346fa3;color:#346fa3;transform:rotate(145deg)}.axis-name{position:absolute;font-family:"Lexend",sans-serif;font-size:11px;font-weight:900}.axis-name.x{right:22px;top:48%;color:#c34556}.axis-name.y{left:51%;top:15px;color:#2a8462}.axis-name.z{left:20px;bottom:35px;color:#346fa3}
.folder-tree{margin-top:17px;border-left:2px solid #bdc9d4}.folder-row{position:relative;margin-left:20px;padding:9px 12px;border-bottom:1px solid #e3e8ed;color:#51687c;font-size:12px;font-weight:700}.folder-row::before{content:"";position:absolute;left:-21px;top:50%;width:18px;border-top:1px solid #bdc9d4}.folder-row b{color:var(--navy)}.prefab-row{display:grid;grid-template-columns:repeat(3,1fr);gap:9px;margin-top:18px}.prefab{padding:16px 8px;border:1px solid #c9d4de;border-radius:12px;background:#f6f9fb;text-align:center}.prefab::before{content:"◇";display:block;color:#567c9f;font-size:28px}.prefab span{font-size:11px;font-weight:800}
.physics-stage{position:relative;height:270px;margin-top:16px;overflow:hidden;border:1px solid #d1dae2;border-radius:14px;background:linear-gradient(#e9f1f7 0 72%,#cbd6df 72%)}.physics-ball{position:absolute;left:18%;top:28px;width:62px;height:62px;border-radius:50%;background:linear-gradient(145deg,#fff,#6f8da8);box-shadow:0 18px 28px -18px #071d33}.gravity-arrow{position:absolute;left:calc(18% + 29px);top:98px;width:4px;height:87px;background:#a33b49}.gravity-arrow::after{content:"";position:absolute;left:-5px;bottom:-2px;border-top:10px solid #a33b49;border-left:7px solid transparent;border-right:7px solid transparent}.trigger-zone{position:absolute;right:10%;bottom:0;width:160px;height:120px;border:3px dashed #315f89;border-bottom:0;background:rgba(49,95,137,.08);color:#315f89;display:grid;place-items:center;font-size:12px;font-weight:900}.physics-label{position:absolute;padding:5px 8px;border-radius:7px;background:#fff;color:#50677b;font-size:10px;font-weight:800}
.code-card{overflow:hidden;padding:0}.code-head{display:flex;align-items:center;justify-content:space-between;padding:12px 16px;background:#173b5b;color:#fff}.code-head span{font-family:"Lexend",sans-serif;font-size:9px;font-weight:800;letter-spacing:1px}.code-dots{display:flex;gap:5px}.code-dots i{width:7px;height:7px;border-radius:50%;background:#8aa0b5}.code-card pre{overflow:auto;padding:20px;background:#071827;color:#dce7f0;font:12px/1.75 "JetBrains Mono",monospace;tab-size:4}.code-card .kw{color:#86c5ff}.code-card .type{color:#f1c57a}.code-card .str{color:#9ad8ac}.code-card .comment{color:#7790a5}
.action-map{display:grid;gap:10px;margin-top:17px}.action-row{display:grid;grid-template-columns:90px 1fr auto;gap:10px;align-items:center;padding:12px;border:1px solid #d0dae3;border-radius:11px}.action-row b{color:var(--navy);font-size:12px}.action-row span{color:#60768a;font-size:11px}.keycaps{display:flex;gap:4px}.key{min-width:26px;padding:4px 6px;border:1px solid #aebdca;border-bottom-width:3px;border-radius:6px;background:#f9fbfc;color:#294b6a;font-family:"Lexend",sans-serif;font-size:8px;font-weight:850;text-align:center}
.ui-map{position:relative;height:280px;margin-top:16px;border:1px solid #c8d3dd;border-radius:15px;background:linear-gradient(145deg,#dfe8ef,#c6d3de);overflow:hidden}.ui-game{position:absolute;inset:18px;border-radius:10px;background:linear-gradient(#7fa3bd 0 58%,#81966f 58%)}.ui-score,.ui-life,.ui-button{position:absolute;z-index:2;padding:7px 10px;border:1px solid rgba(255,255,255,.65);border-radius:8px;background:rgba(7,29,51,.82);color:#fff;font-size:10px;font-weight:850}.ui-score{left:32px;top:32px}.ui-life{right:32px;top:32px}.ui-button{left:50%;bottom:35px;transform:translateX(-50%);background:#fff;color:var(--navy)}
.sense-stack{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:18px}.sense{min-height:150px;padding:18px 12px;border:1px solid #cbd5de;border-radius:14px;background:#f8fafb;text-align:center}.sense b{display:block;color:var(--blue);font-family:"Lexend",sans-serif;font-size:10px;letter-spacing:1px}.sense strong{display:block;margin-top:12px;color:var(--navy);font-size:18px}.sense span{display:block;margin-top:8px;color:#64788b;font-size:11px;line-height:1.55}
.test-board{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin-top:17px}.test-col{min-height:245px;padding:13px;border:1px solid #cbd5de;border-radius:12px;background:#f8fafb}.test-col b{display:block;padding-bottom:10px;border-bottom:1px solid #d8e0e7;color:var(--navy);font-size:11px}.test-note{margin-top:9px;padding:9px;border-radius:8px;background:#fff;color:#61768a;font-size:10px;line-height:1.5}.test-note.high{border-left:3px solid var(--red)}.test-note.mid{border-left:3px solid var(--orange)}.test-note.done{border-left:3px solid var(--green)}
.build-flow{display:flex;align-items:stretch;gap:7px;margin-top:17px}.build-step{flex:1;padding:15px 9px;border:1px solid #cad5de;border-radius:12px;background:#f8fafb;text-align:center}.build-step b{display:block;color:var(--blue);font-family:"Lexend",sans-serif;font-size:9px}.build-step span{display:block;margin-top:7px;color:var(--navy);font-size:11px;font-weight:850;line-height:1.4}.build-arrow{align-self:center;color:#8b9cac;font-weight:900}
.lesson-finish{padding:42px 38px;border-color:#183c5c;background:linear-gradient(135deg,#071b30,#173b5b);color:#fff}.finish-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(230px,.36fr);gap:28px;align-items:center}.finish-kicker{color:#91aac0;font-family:"Lexend",sans-serif;font-size:9px;font-weight:800;letter-spacing:2px;text-transform:uppercase}.lesson-finish h2{margin-top:9px;font-size:clamp(30px,4vw,48px);line-height:1.1;letter-spacing:-1.8px;word-break:keep-all}.lesson-finish p{margin-top:14px;max-width:700px;color:#c5d3df;font-size:14px;line-height:1.75;word-break:keep-all}.deliverable{padding:20px;border:1px solid rgba(255,255,255,.24);border-radius:16px;background:rgba(255,255,255,.06)}.deliverable b{display:block;font-size:13px}.deliverable span{display:block;margin-top:7px;color:#b9cad8;font-size:11px;line-height:1.65}
.source-box{padding:21px 25px;border:1px solid #d0dae3;border-radius:18px;background:rgba(255,255,255,.72);color:#66798b;font-size:11px;line-height:1.7}.source-box strong{color:var(--navy)}.source-links{display:flex;flex-wrap:wrap;gap:7px;margin-top:10px}.source-links a{padding:6px 9px;border:1px solid #c5d0da;border-radius:999px;background:#fff;color:#294d6d;font-weight:800}.lesson-pager{display:grid;grid-template-columns:1fr 1fr;gap:10px}.pager-link{padding:16px 18px;border:1px solid #cbd5de;border-radius:15px;background:rgba(255,255,255,.8)}.pager-link.next{text-align:right}.pager-link small{display:block;color:#8392a1;font-family:"Lexend",sans-serif;font-size:8px;font-weight:800;letter-spacing:1px}.pager-link b{display:block;margin-top:4px;color:var(--navy);font-size:13px}
@media(max-width:920px){.lesson-hero{grid-template-columns:1fr}.hero-board{max-width:700px}.lesson-layout{grid-template-columns:1fr}.lesson-nav{position:static;display:flex;gap:4px;overflow-x:auto}.nav-label{display:none}.lesson-nav a{min-width:max-content}.section-grid{grid-template-columns:1fr}.visual{order:-1}.finish-grid{grid-template-columns:1fr}}
@media(max-width:580px){.lesson-topbar-inner,.lesson-hero,.lesson-layout{width:min(100% - 24px,1180px)}.lesson-brand small{display:none}.top-link:not(.primary){display:none}.lesson-hero{gap:25px;padding:38px 0 32px}.lesson-hero h1{font-size:45px;letter-spacing:-2.7px}.hero-lead{font-size:15px}.hero-board{min-height:300px;padding:22px}.board-flow{gap:4px}.board-node{padding:12px 6px}.board-node b{font-size:8px}.board-node span{font-size:11px}.lesson-section{border-radius:18px}.section-copy{padding:28px 22px}.visual{padding:12px}.visual-card{padding:17px}.window-map{grid-template-columns:1fr 1fr;grid-template-rows:95px 115px 76px}.window-box.hierarchy{grid-column:1;grid-row:1}.window-box.inspector{grid-column:2;grid-row:1}.window-box.scene{grid-column:1/3;grid-row:2}.window-box.project{grid-column:1/3;grid-row:3}.prefab-row,.sense-stack,.test-board{grid-template-columns:1fr}.action-row{grid-template-columns:75px 1fr}.keycaps{grid-column:1/3}.build-flow{display:grid;grid-template-columns:1fr 1fr}.build-arrow{display:none}.lesson-finish{padding:32px 23px}.lesson-pager{grid-template-columns:1fr}.pager-link.next{text-align:left}}