:root{--bg:#f6f7f9;--fg:#1b1f24;--muted:#6a737d;--card:#fff;--line:#e1e4e8;--pri:#1f6feb;--ok:#2da44e;--warn:#bf8700;--bad:#cf222e;--mono:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
*{box-sizing:border-box}html,body{margin:0;height:100%}
body{font:15px/1.5 system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--fg)}
a{color:var(--pri);text-decoration:none}a:hover{text-decoration:underline}
nav.top{display:flex;align-items:center;gap:16px;padding:10px 20px;background:#fff;border-bottom:1px solid var(--line)}
nav.top .brand{font-weight:700;color:var(--fg)}nav.top .spacer{flex:1}nav.top .who{color:var(--muted)}
.container{max-width:1100px;margin:24px auto;padding:0 16px}
.card{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:20px;margin-bottom:16px}
.card.row{display:flex;justify-content:space-between;align-items:center;gap:16px}
.card.login{max-width:520px;margin:60px auto;text-align:center}.card.login .dev{display:flex;flex-direction:column;gap:8px;text-align:left}
h1{font-size:24px;margin:0 0 8px}h2{font-size:20px;margin:0 0 8px}h3{font-size:16px;margin:16px 0 6px}
.muted{color:var(--muted)}.small{font-size:13px}
.btn{display:inline-block;border:1px solid var(--line);background:#fff;color:var(--fg);padding:7px 14px;border-radius:7px;cursor:pointer;font:inherit;font-size:14px}
.btn:hover{background:#f0f2f5;text-decoration:none}.btn.primary{background:var(--pri);border-color:var(--pri);color:#fff}.btn.primary:hover{background:#1a5fd0}
.btn.danger{background:var(--bad);border-color:var(--bad);color:#fff}.btn.big{padding:12px 22px;font-size:16px}.btn.sm{padding:3px 9px;font-size:12px}
.btn[disabled]{opacity:.5;cursor:wait}
.alert{background:#fff4e5;border:1px solid #f0c36d;color:#7a4b00;padding:10px 14px;border-radius:8px;margin:12px 0}
.pill{display:inline-block;padding:2px 10px;border-radius:999px;background:#eef1f4;font-size:13px}.pill.ok{background:#dafbe1;color:#116329}.pill.warn{background:#fff1c2;color:#7a4b00}.pill.bad{background:#ffe2e0;color:#8a1a1a}
.tbl{width:100%;border-collapse:collapse;background:#fff}.tbl th,.tbl td{border-bottom:1px solid var(--line);padding:7px 9px;text-align:left;vertical-align:top}.tbl th{background:#f3f5f7;font-weight:600}
.tbl tr.stale td{background:#fff8e6}.tbl tr.locked td{background:#ffecec}
input,select,textarea{font:inherit;padding:7px 9px;border:1px solid var(--line);border-radius:6px;width:100%}
label{display:block;font-size:13px;color:var(--muted);margin-top:10px}label.check{color:var(--fg);font-size:15px;margin:14px 0}label.check input{width:auto;margin-right:8px}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
pre{background:#f3f5f7;padding:8px 10px;border-radius:6px;overflow:auto;font-family:var(--mono);font-size:13px;margin:4px 0}
.md table{border-collapse:collapse;margin:8px 0}.md td,.md th{border:1px solid var(--line);padding:4px 10px}.md code{background:#eef1f4;padding:1px 5px;border-radius:4px;font-family:var(--mono)}
/* exam */
body.exam{overflow:hidden}
.exam-bar .timer{font-family:var(--mono);font-size:20px;font-weight:700;padding:2px 10px;border-radius:6px;background:#eef1f4}.exam-bar .timer.low{background:#ffe2e0;color:var(--bad)}
.exam-main{height:calc(100vh - 53px);display:flex;flex-direction:column}
.tabs{display:flex;gap:4px;padding:8px 12px 0;background:#fff;border-bottom:1px solid var(--line)}
.tab{border:1px solid var(--line);border-bottom:none;background:#f3f5f7;padding:8px 16px;border-radius:8px 8px 0 0;cursor:pointer;font:inherit}.tab.active{background:#fff;font-weight:600}.tab-status{color:var(--ok);margin-left:6px;font-size:12px}
.panel{display:none;flex:1;min-height:0}.panel.active{display:grid;grid-template-columns:minmax(320px,42%) 1fr}
.statement{overflow:auto;padding:16px 20px;background:#fff;border-right:1px solid var(--line)}
.sample{display:grid;grid-template-columns:1fr 1fr;gap:10px}.lbl{font-size:12px;color:var(--muted)}
.work{display:flex;flex-direction:column;min-height:0;background:#fafbfc}
.editor{flex:1;min-height:200px;overflow:auto;border-bottom:1px solid var(--line)}.editor .cm-editor{height:100%}.cm-editor{font-size:14px}
.toolbar{display:flex;gap:8px;align-items:center;padding:8px 12px;background:#fff;border-bottom:1px solid var(--line)}.save-state{margin-left:auto;font-size:12px;color:var(--muted)}
.custom-input{height:60px;resize:vertical;border-radius:0;border-left:none;border-right:none;font-family:var(--mono);font-size:13px}
.output{height:34%;min-height:140px;overflow:auto;padding:10px 12px;font-family:var(--mono);font-size:13px;white-space:pre-wrap}
.output .case{border:1px solid var(--line);border-radius:6px;padding:6px 8px;margin-bottom:6px;background:#fff}.output .case.pass{border-color:var(--ok)}.output .case.fail{border-color:var(--bad)}
.output .hd{font-weight:600}.output .pass .hd{color:var(--ok)}.output .fail .hd{color:var(--bad)}.output .err{color:var(--bad)}
.overlay{position:fixed;inset:0;background:rgba(10,12,16,.75);display:flex;align-items:center;justify-content:center;z-index:50}.overlay.hidden{display:none}
.overlay-box{background:#fff;padding:28px 32px;border-radius:12px;max-width:480px;text-align:center}
.instructions{background:#f3f5f7;padding:10px 14px;border-radius:8px}
.score{margin-top:4px}.ok{color:var(--ok)}.bad{color:var(--bad)}
.mono{font-family:var(--mono);font-size:13px}
.inline{display:inline-flex;gap:6px;align-items:center}.inline input,.inline select{width:auto}
.events{max-height:300px;overflow:auto;font-size:13px}