:root{--ink:#18243c;--muted:#65708a;--paper:#fffdfa;--navy:#162b55;--blue:#3867ec;--blue-soft:#eaf0ff;--line:#e6e9f0;--mint:#e7f7f2;--danger:#a63d3d}*{box-sizing:border-box}body{margin:0;background:linear-gradient(140deg,#f7f5ef,#f3f7ff);color:var(--ink);font-family:Arial,"Noto Sans KR",sans-serif;min-height:100vh}.shell{max-width:1120px;margin:auto;padding:32px 22px 64px}header,.topline,.card-head{display:flex;justify-content:space-between;align-items:center;gap:16px}header{margin-bottom:54px}.brand{font-size:21px;font-weight:800;letter-spacing:-.8px}.brand-mark{display:inline-grid;place-items:center;background:var(--navy);color:#fff;border-radius:10px;width:32px;height:32px;margin-right:7px}header p,.panel p,.share-stack p,.student-share p{color:var(--muted);line-height:1.65}.hero{max-width:790px;margin:10vh auto;text-align:center}.eyebrow{font-size:12px;letter-spacing:1.3px;color:var(--blue);font-weight:800;text-transform:uppercase}h1{font-size:clamp(38px,7vw,72px);letter-spacing:-4px;line-height:1.1;margin:14px 0 20px}h1 em{font-style:normal;color:var(--blue)}.lead{font-size:18px}.choice-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:18px;margin-top:38px}.role-card{border:1px solid var(--line);background:#ffffffdc;border-radius:22px;padding:32px 20px;text-align:left;cursor:pointer;box-shadow:0 12px 30px #14264b0a;transition:.2s}.role-card:hover{border-color:var(--blue);transform:translateY(-3px)}.role-card span,.role-card strong,.role-card small{display:block}.role-card span{font-size:30px;color:var(--blue);margin-bottom:18px}.role-card strong{font-size:19px;margin-bottom:8px}.role-card small{color:var(--muted)}.panel,.dashboard{background:#ffffffde;border:1px solid #fff;border-radius:24px;padding:clamp(24px,5vw,48px);box-shadow:0 18px 55px #17295c12;max-width:1040px;margin:auto}.panel{max-width:700px}.panel h2,.dashboard h2{letter-spacing:-1px;margin:10px 0}.panel label{display:block;font-weight:700;margin:22px 0 8px}input{width:100%;padding:13px 14px;border:1px solid var(--line);border-radius:10px;color:var(--ink);font:inherit}button{border:0;border-radius:10px;padding:12px 16px;color:var(--ink);font:inherit;font-weight:700;cursor:pointer}.primary{background:var(--blue);color:#fff;margin-top:16px}.outline{background:#fff;border:1px solid var(--blue);color:var(--blue);margin-top:14px}.quiet,.back{background:transparent;color:var(--muted);padding:6px}.code-card{display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:12px;background:var(--blue-soft);padding:18px;border-radius:14px;margin:24px 0}.code-card strong{font-size:24px;letter-spacing:3px}.code-card small{grid-column:1/-1;color:var(--muted)}.tabs{display:flex;border-bottom:1px solid var(--line);margin:26px 0 18px;gap:6px}.tab{border-radius:10px 10px 0 0;background:transparent;color:var(--muted)}.tab.active{color:var(--blue);background:var(--blue-soft)}.notice{background:var(--mint);padding:13px 15px;border-radius:10px;margin-bottom:16px}.student-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:16px}.student-card{border:1px solid var(--line);border-radius:14px;overflow:hidden;background:#fff}.student-video,.student-placeholder{display:block;width:100%;aspect-ratio:16/10;background:#15243f;object-fit:cover}.student-placeholder,.screen-empty{display:grid;place-items:center;text-align:center;color:var(--muted);padding:28px}.student-meta{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:13px}.status{display:inline-block;border-radius:99px;background:#eef0f4;color:var(--muted);padding:4px 9px;font-size:12px;font-weight:700;white-space:nowrap}.status.live{background:#dff5eb;color:#167353}.status.ended{background:#fbe8e8;color:var(--danger)}.share-stack article,.student-share,.teacher-screen,.dashboard>article{border:1px solid var(--line);border-radius:14px;padding:20px;margin:16px 0}.form-row{display:flex;gap:8px;align-items:center}.share-list{display:grid;gap:8px}.share-item{display:flex;justify-content:space-between;gap:12px;padding:12px;background:var(--blue-soft);border-radius:10px}.teacher-screen img{width:100%;max-height:540px;object-fit:contain;background:#15243f}.share-warning{background:#fff4df;border-left:4px solid #d28b1f;padding:11px 12px}.network-note{font-size:13px}.student-share details{margin-top:14px;color:var(--muted)}.student-share li{margin:8px 0}.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);background:var(--navy);color:#fff;padding:12px 16px;border-radius:10px;z-index:2}.hidden{display:none!important}@media(max-width:650px){.shell{padding:22px 14px 40px}header{margin-bottom:30px}header p{display:none}.choice-grid{grid-template-columns:1fr}.code-card{grid-template-columns:1fr}.form-row{align-items:stretch;flex-direction:column}.topline{align-items:flex-start}.student-grid{grid-template-columns:1fr}.panel,.dashboard{padding:24px 18px}}