:root{color-scheme:dark;--bg:#090806;--panel:#11100d;--line:#332b21;--text:#f1eadf;--muted:#a79e92;--accent:#e4a234;--green:#b8e5cd;--orange:#f1c994;font:15px/1.65 system-ui,-apple-system,"Microsoft YaHei",sans-serif}*{box-sizing:border-box}body{margin:0;background:radial-gradient(ellipse at 75% 0%,#2a1d0e 0,transparent 38%),var(--bg);color:var(--text);min-height:100vh}button,input,textarea,select{font:inherit}a{color:inherit;text-decoration:none}button,.button{border:1px solid var(--line);border-radius:10px;background:#252017;color:var(--text);padding:10px 16px;cursor:pointer;display:inline-flex;justify-content:center;align-items:center;gap:7px}button:hover,.button:hover{border-color:var(--accent);background:#352b1c}button:disabled{opacity:.5;cursor:wait}.primary{background:var(--accent);color:#090806;border-color:transparent;font-weight:650}.primary:hover{background:#ffc85a;color:#090806}.quiet{background:transparent}.small{font-size:12px;padding:5px 10px}input,textarea,select{border:1px solid #443a2c;border-radius:9px;background:#0d0b08;color:var(--text);padding:11px 12px;width:100%}textarea{min-height:110px;resize:vertical}input:focus,textarea:focus,select:focus,button:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:3px}label{display:block;font-size:13px;margin-bottom:6px;color:var(--muted)}.top{height:82px;border-bottom:1px solid var(--line);padding:0 5vw;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{font-size:22px;font-weight:750;letter-spacing:2px}.brand span{font-size:10px;font-weight:500;letter-spacing:2px;color:var(--muted);margin-left:15px}#identity{font-size:13px;display:flex;align-items:center;gap:16px;color:var(--muted)}main{max-width:1180px;margin:auto;padding:48px 24px 72px;min-height:calc(100vh - 180px)}h1,h2,h3,p{margin-top:0}h1{font-size:clamp(30px,4vw,48px);letter-spacing:-1.4px;font-weight:650;line-height:1.25;margin-bottom:20px}h2{font-size:23px;line-height:1.4}h3{font-size:17px}p{color:var(--muted)}.eyebrow{font-size:11px;letter-spacing:2px;color:var(--accent);margin-bottom:14px}.hero{margin-bottom:36px;max-width:770px}.hero p{font-size:16px;max-width:620px}.login{display:grid;grid-template-columns:1.3fr 1fr;gap:90px;align-items:center;min-height:64vh}.login .panel{max-width:400px}.login .field{margin-bottom:20px}.login h1{font-size:56px}.panel{background:var(--panel);border:1px solid var(--line);border-radius:18px;padding:26px}.muted{color:var(--muted)}.tiny{font-size:12px}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.experiment{min-height:300px;display:flex;flex-direction:column;position:relative;overflow:hidden}.experiment .num{font-size:57px;line-height:1;color:#63502f;margin-bottom:25px;letter-spacing:-4px}.experiment:nth-child(2) .num{color:#58675e}.experiment:nth-child(3) .num{color:#615348}.experiment h2{margin-bottom:9px}.experiment p{font-size:14px;flex:1}.card-bottom{display:flex;align-items:center;justify-content:space-between;gap:12px}.pill{font-size:11px;display:inline-block;border:1px solid var(--line);border-radius:30px;padding:3px 10px;color:var(--muted);white-space:nowrap}.pill.done{color:var(--green);border-color:#395647}.pill.working{color:var(--accent);border-color:#80602b}.pill.help{color:var(--orange);border-color:#634b31}.submission-bar{display:flex;align-items:center;justify-content:space-between;gap:30px;margin-top:22px}.submission-bar h3{margin:0 0 5px}.submission-bar p{margin:0;font-size:13px}.back{margin-bottom:26px;display:inline-block;color:var(--muted);font-size:13px}.detail-head{display:flex;justify-content:space-between;gap:22px;align-items:flex-start}.detail-head h1{font-size:36px;margin:8px 0 15px}.two{display:grid;grid-template-columns:1.65fr 1fr;gap:22px;align-items:start}.stack{display:grid;gap:20px}.step{display:flex;gap:16px;margin:20px 0}.step b{display:grid;place-items:center;flex:0 0 28px;height:28px;font-size:12px;background:#302517;border-radius:50%;color:var(--accent)}.step p{margin:0;font-size:14px}.step strong{display:block;color:var(--text);font-size:15px;margin-bottom:3px}.actions{display:flex;flex-wrap:wrap;gap:9px;margin-top:16px}.actions .active{border-color:var(--accent);color:var(--accent)}.prompt{font-size:13px;min-height:165px;line-height:1.7;margin-top:12px}.divider{height:1px;background:var(--line);margin:24px 0}.hint{border-left:2px solid #a8792d;padding-left:14px;font-size:13px}.helpbox{margin-top:20px}.helpbox summary{cursor:pointer;color:var(--orange);font-size:13px}.helpbox textarea{margin-top:12px}.lab{width:100%;height:1000px;border:1px solid var(--line);border-radius:16px;background:#090806;display:block}.labbar{display:flex;gap:15px;align-items:center;justify-content:space-between;margin:18px 0}.files{padding:0;list-style:none;margin:18px 0}.file{padding:15px 0;border-bottom:1px solid var(--line);display:flex;gap:12px;align-items:center;justify-content:space-between}.file-name{overflow-wrap:anywhere}.file .tiny{margin-top:3px}.error{color:#ffb4b9;font-size:13px;margin:12px 0;min-height:20px}.success{color:var(--green)}.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-bottom:26px}.stat strong{font-size:32px;display:block;line-height:1.2}.stat span{font-size:12px;color:var(--muted)}.toolbar{display:flex;gap:12px;align-items:center;margin:18px 0}.toolbar input{max-width:280px}.toolbar select{max-width:170px}.table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:14px}table{width:100%;border-collapse:collapse;font-size:13px;white-space:nowrap}th,td{text-align:left;padding:15px 16px;border-bottom:1px solid var(--line)}th{color:var(--muted);font-weight:500;background:#19150f}tbody tr:hover{background:#211b12}td .tiny{display:block;color:var(--muted)}.teacher-head{display:flex;align-items:flex-start;justify-content:space-between;gap:20px}.student-detail{margin-top:28px}.student-detail pre{white-space:pre-wrap;word-break:break-word;font:13px/1.7 inherit;background:#0d0b08;padding:18px;border-radius:8px}.help-item{padding:15px;border:1px solid #53422d;border-radius:10px;margin:12px 0}.help-item p{white-space:pre-wrap;overflow-wrap:anywhere;margin:7px 0}.preview{max-width:100%;max-height:400px;border-radius:9px;display:block;margin:12px 0}#notice{position:fixed;bottom:25px;left:50%;transform:translateX(-50%);padding:12px 20px;border:1px solid #80602b;background:#2c2112;border-radius:12px;box-shadow:0 10px 40px #0008;z-index:5;max-width:90vw;display:none}#notice.show{display:block}footer{max-width:1180px;margin:auto;padding:25px 24px;color:#8f867b;font-size:12px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:20px}.loading{padding:100px;text-align:center;color:var(--muted)}progress{width:100%;accent-color:var(--accent);margin-top:15px}.empty{padding:26px;text-align:center;font-size:14px;color:var(--muted)}[hidden]{display:none!important}@media(max-width:800px){.login{grid-template-columns:1fr;gap:25px;min-height:auto}.login h1{font-size:42px}.login .panel{max-width:none}.two{grid-template-columns:1fr}.grid{grid-template-columns:1fr}.experiment{min-height:220px}.experiment .num{position:absolute;right:24px;top:24px;font-size:44px}.experiment h2{margin-right:50px}.experiment p{max-width:85%;margin:10px 0 25px}.stats{grid-template-columns:repeat(2,1fr)}.toolbar{flex-wrap:wrap}.teacher-head{flex-direction:column}.brand span{display:none}.top{padding:0 20px;height:70px}main{padding:30px 18px 45px}.submission-bar{align-items:flex-start;flex-direction:column;gap:18px}.panel{padding:21px}.detail-head{flex-direction:column;gap:4px}.labbar{align-items:flex-start;flex-direction:column}footer{flex-direction:column;gap:3px}.lab{height:1650px}.file{align-items:flex-start}.card-bottom{margin-top:auto}#identity{gap:8px;font-size:12px}}@media(prefers-reduced-motion:no-preference){button,.button{transition:background .16s,border .16s}.experiment:hover{border-color:#7d5d2b}}

.stats{grid-template-columns:repeat(5,1fr)}.topic-short{min-width:180px;max-width:240px;white-space:normal;font-size:12px;color:#e4b76a}#topic-stats{grid-template-columns:repeat(4,1fr);padding-top:20px}@media(max-width:800px){.stats{grid-template-columns:repeat(2,1fr)}#topic-stats{grid-template-columns:repeat(2,1fr)}}

/* Dfty brand: amber accent, brighter keyboard focus and hover. */
:root{--accent-hover:#ffc85a}::selection{background:var(--accent-hover);color:#090806}input:focus,textarea:focus,select:focus,button:focus-visible,a:focus-visible{outline-color:var(--accent-hover)}

/* Account management and identity confirmation. */
dialog{color:var(--text);background:var(--panel);border:1px solid var(--line);border-radius:18px;padding:28px;width:min(560px,calc(100vw - 28px));max-height:90vh;overflow:auto}dialog::backdrop{background:#000b}dialog label{margin-top:16px}.danger{color:#ffb4b9;border-color:#78454a}.identity-card{padding:20px;background:#211a10;border-radius:12px;margin-bottom:22px}.identity-card strong{font-size:28px}.identity-card p{margin:5px 0}.detail-actions{float:right;margin:0 0 12px 12px}@media(max-width:800px){.detail-actions{float:none;margin:0 0 18px}.teacher-head .actions{margin:0 0 20px}}

.stats{grid-template-columns:repeat(6,1fr)}.website-report{border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin:22px 0;padding:22px 0}.website-changes{padding-left:20px}.website-changes li{margin:8px 0;overflow-wrap:anywhere}.website-report code{font-size:12px}@media(max-width:1000px){.stats{grid-template-columns:repeat(3,1fr)}}@media(max-width:800px){.stats{grid-template-columns:repeat(2,1fr)}}