*{box-sizing:border-box}body{margin:0;background:#f7f8f2;color:#182f35;font:15px/1.55 system-ui,-apple-system,'Segoe UI',Roboto,sans-serif}header{background:#142d39;color:white}.top{max-width:1100px;padding:15px 22px;margin:auto;display:flex;align-items:center;justify-content:space-between}.top a{color:white;text-decoration:none;font-weight:800;font-size:21px;letter-spacing:.03em}.top small{display:block;font-size:10px;opacity:.75;font-weight:600}h1{font-size:clamp(30px,4vw,43px);margin:7px 0}h2{font-size:22px;margin:0 0 7px}p{margin:6px 0 19px;color:#5c7073}.eyebrow{font-size:11px;letter-spacing:.12em;font-weight:800;color:#587a65}main{max-width:1100px;margin:25px auto;padding:0 20px 50px}.panel{background:white;padding:22px;border-radius:18px;border:1px solid #dfe8e0;margin-bottom:17px;box-shadow:0 3px 12px #0e352108}.login{max-width:490px;margin:45px auto;padding:35px}.login input{width:100%;margin:9px 0 15px}.login label{font-weight:700}input{font-size:16px;padding:12px 14px;border-radius:10px;border:1px solid #bac9c2;color:#183a34;min-width:0}button{border:1px solid #b7cabc;background:#fff;padding:10px 15px;color:#244239;border-radius:10px;font-weight:700;cursor:pointer;font-size:14px}button:hover{filter:brightness(.94)}button:focus-visible,input:focus-visible{outline:3px solid #e7a55f;outline-offset:2px}button:disabled{opacity:.5;cursor:wait}.primary{background:#375e49;color:#fff;border-color:#375e49}.head,.results-heading{display:flex;justify-content:space-between;gap:15px;align-items:center}.stats{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.stats .panel{padding:19px}.stats span{font-size:11px;letter-spacing:.08em;color:#6b827a;font-weight:700}.stats strong{display:block;font-size:32px;margin-top:2px}.telegram{background:#f0f6e9}.row{display:flex;gap:9px;flex-wrap:wrap}.muted{font-size:13px;margin-top:16px}.chat-results{padding:13px;margin-top:12px;border-radius:10px;background:#fff}.chat-results button{display:block;margin:8px 0}.results-heading input{max-width:330px;width:100%}.result{border-top:1px solid #e3eae3;padding:16px 0}.result summary{cursor:pointer;list-style:none;display:flex;justify-content:space-between;gap:12px;align-items:center}.result summary::-webkit-details-marker{display:none}.who strong{display:block;font-size:16px}.who small{color:#678078}.score{font-size:23px;font-weight:800;white-space:nowrap}.score small{font-size:12px;color:#71817a;font-weight:500}.tag{font-size:12px;border-radius:7px;padding:3px 8px;background:#eaf4e6;color:#387042;margin-left:7px}.tag.warn{background:#fff0e8;color:#b64f31}.details{margin-top:12px;border-top:1px dashed #ddd;padding-top:10px}.wrong{padding:12px;border-radius:12px;background:#fff5ee;margin:8px 0;font-size:14px}.wrong b{display:block}.wrong p{margin:5px 0;color:#415457}.message{position:fixed;bottom:30px;left:20px;right:20px;max-width:650px;margin:auto;padding:15px;border-radius:12px;background:#fff0e9;color:#71290b;border:1px solid #d7a988;box-shadow:0 8px 28px #0002}.hidden{display:none!important}.link{background:none;color:white;border-color:#8ea3a0}@media(max-width:620px){main{padding:0 11px}.login{margin:20px auto;padding:24px}.panel{padding:16px}.stats{gap:6px}.stats .panel{padding:10px;border-radius:10px}.stats span{font-size:9px}.stats strong{font-size:25px}.head{align-items:flex-start}.head button{font-size:12px}.results-heading{align-items:stretch;flex-direction:column}.results-heading input{max-width:none}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}

/* Task content comes from server-owned generators, never student input. */
.task-figure,.task-context{max-width:100%;overflow:auto;margin:12px 0}.task-figure svg,.task-context svg{display:block;max-width:100%;height:auto;margin:auto}.task-context summary{font-size:14px;font-weight:700}.task-context table{border-collapse:collapse;width:100%}.task-context td,.task-context th{border:1px solid #cbd6ce;padding:6px}.math-block{font-family:Georgia,'Times New Roman',serif;font-size:24px;line-height:1.7;text-align:center;padding:12px}.math-block sup{font-size:.65em}.frac{display:inline-flex;vertical-align:middle;align-items:stretch;flex-direction:column;text-align:center;line-height:1.24;white-space:nowrap;margin:0 .1em}.frac>span:first-child{border-bottom:1.4px solid currentColor;padding:0 .19em .11em}.frac>span:last-child{padding:.12em .19em 0}.who{min-width:0;overflow-wrap:anywhere}.wrong{overflow-wrap:anywhere}
.resource-panel{background:#fff;border:1px solid #dbe3e6;border-radius:18px;padding:22px;margin:20px 0}.resource-panel a{display:inline-block;margin:8px 24px 8px 0}.resource-panel details,#student-grants details{padding:10px 0;border-bottom:1px solid #e1e8eb}.resource-panel summary,#student-grants summary{cursor:pointer;padding:8px}.resource-panel button{margin:8px;padding:12px;border:1px solid #cbd9df;border-radius:10px;background:#f4f8fa;color:#142d39;cursor:pointer}.material-viewer{width:min(1000px,94vw);max-height:94vh;overflow:auto;border:0;border-radius:18px;padding:20px;color:#142d39;user-select:none}.material-viewer::backdrop{background:#102631ba}.material-viewer video,.pdf-page{display:block;width:100%;height:auto;background:#eef2f4}.material-viewer video{max-height:65vh;background:#000}.media-controls{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin:16px 0}.media-controls button,.material-viewer>button,.media-controls select{padding:12px;border-radius:8px;border:1px solid #cbd9df;background:#fff;cursor:pointer}.media-controls input[type=range]{flex:1;min-width:140px}.material-viewer h2{font-size:22px}.material-row{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin:16px 0;padding-top:16px;border-top:1px solid #dbe3e6}.material-row input{flex:1;min-width:180px}#student-list{display:flex;flex-wrap:wrap;gap:10px;margin-top:20px}#student-grants input[type=checkbox]{width:auto;margin:0 8px 0 0}#student-grants label{display:block;margin:10px 0}#student-edit-form textarea{width:100%;font:inherit;padding:12px;box-sizing:border-box}#material-upload select,#student-edit-form input{max-width:100%}@media print{.material-viewer{display:none!important}}
#student-edit-form>label,#material-upload>label{display:block;font-weight:600;margin:16px 0 6px}#student-edit-form>input,#material-upload>input,#material-upload>select{display:block;width:100%;margin-bottom:12px}#student-edit-form>button,#material-upload>button{margin-top:16px}#student-edit-form select,#material-upload select{font:inherit;padding:12px;border:1px solid #bac9c2;border-radius:10px;background:white}#student-save-status{margin:12px 0;color:#285f45}
#student-create-form{display:grid;gap:12px;margin:16px 0 24px}#student-code-dialog{max-width:520px;width:90%;border:0;border-radius:18px;padding:28px;color:#183a34}#student-code-dialog::backdrop{background:#142d39aa}#issued-code{display:block;font:700 32px monospace;letter-spacing:.12em;padding:16px 0;user-select:all}#student-code-dialog button{margin:8px 8px 0 0}#student-reset-code{margin-bottom:10px}

/* Fullscreen video keeps the custom playback controls visible. */
.video-player:fullscreen{box-sizing:border-box;width:100%;height:100%;padding:16px;display:flex;flex-direction:column;background:#000;color:#fff;overflow:auto}
.video-player:-webkit-full-screen{box-sizing:border-box;width:100%;height:100%;padding:16px;display:flex;flex-direction:column;background:#000;color:#fff;overflow:auto}
.material-viewer .video-player:fullscreen video{flex:1;min-height:0;height:0;max-height:none;object-fit:contain}
.material-viewer .video-player:-webkit-full-screen video{flex:1;min-height:0;height:0;max-height:none;object-fit:contain}
.video-player:fullscreen .media-controls,.video-player:-webkit-full-screen .media-controls{flex-shrink:0}
.video-player [role=alert]:empty{display:none}

/* PDF zoom and a shared workspace for PDF + video. */
.study-viewer{width:min(1500px,96vw);box-sizing:border-box}
.study-layout{display:grid;grid-template-columns:minmax(0,1fr);gap:20px}
.study-layout.paired{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
.material-pane{min-width:0;box-sizing:border-box}
.pdf-viewport{overflow:auto;max-height:65vh;background:#e5eaed;overscroll-behavior:contain}
.pdf-viewport .pdf-page{max-width:none;flex:none}
.study-stage:fullscreen,.material-pane:fullscreen{width:100%;height:100%;max-width:none;max-height:none;margin:0;padding:16px;border-radius:0;background:#fff;color:#142d39;overflow:auto;box-sizing:border-box}
.study-stage:-webkit-full-screen,.material-pane:-webkit-full-screen{width:100%;height:100%;max-width:none;max-height:none;margin:0;padding:16px;background:#fff;color:#142d39;overflow:auto;box-sizing:border-box}
.material-pane:fullscreen .pdf-viewport{max-height:calc(100vh - 180px)}
.study-stage:fullscreen .pdf-viewport{max-height:calc(100vh - 260px)}
@media(max-width:760px){.study-layout.paired{grid-template-columns:minmax(0,1fr)}.study-layout.paired .pdf-viewport{max-height:42vh}.study-layout.paired video{max-height:35vh}.study-viewer{padding:12px}.media-controls{gap:8px}}