:root{--bg:#f3f5f9;--card:#fff;--text:#1d2433;--muted:#6b7385;--pri:#2457c5;--ok:#1f8a4c;--okbg:#e8f6ee;--bad:#c0392b;--badbg:#fdecea;--line:#dde2ec}
*{box-sizing:border-box}
body{margin:0;font-family:system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;background:var(--bg);color:var(--text);line-height:1.5}
.muted{color:var(--muted)}
.wrap{max-width:860px;margin:0 auto;padding:20px 14px 60px}
.card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin-bottom:16px;box-shadow:0 1px 3px rgba(0,0,0,.04)}
.topbar{position:sticky;top:0;z-index:5;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:8px;background:#fff;border-bottom:1px solid var(--line);padding:10px 18px}
.topbar nav{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.btn{display:inline-block;background:var(--pri);color:#fff;border:0;border-radius:8px;padding:10px 18px;font-size:1rem;cursor:pointer;text-decoration:none}
.btn:hover{filter:brightness(1.1)}
.btn-small{padding:6px 12px;font-size:.9rem}
.btn-ghost{background:transparent;color:var(--pri);border:1px solid var(--pri)}
.btn-big{padding:14px 28px;font-size:1.1rem}
.submit-row{text-align:center;margin-top:24px}
.login-page{display:flex;min-height:100vh;align-items:center;justify-content:center;padding:14px}
.login-card{width:100%;max-width:380px}
.login-card h1{margin:0 0 4px}
.login-card label{display:block;margin:14px 0 4px;font-weight:600}
.login-card input{width:100%;padding:10px;border:1px solid var(--line);border-radius:8px;font-size:1rem;margin-top:4px}
.login-card .btn{width:100%;margin-top:18px}
.alert{background:var(--badbg);color:var(--bad);border-radius:8px;padding:10px;margin:12px 0}
.qhead{display:flex;align-items:center;gap:8px;flex-wrap:wrap;margin-bottom:6px}
.qnum{font-weight:700;font-size:1.1rem}
.tag{background:#eef2fb;color:var(--pri);border-radius:20px;padding:2px 10px;font-size:.8rem}
.tag-type{background:#f2f2f2;color:#555}
.qtext{font-weight:600;margin:6px 0 12px}
.options{display:flex;flex-direction:column;gap:6px}
.opt{display:flex;gap:8px;align-items:flex-start;border:1px solid var(--line);border-radius:8px;padding:8px 10px;cursor:pointer}
.opt:hover{background:#f8f9fc}
.opt input{margin-top:4px}
.letter{font-weight:700;min-width:1.2em}
.opt-correct{background:var(--okbg);border-color:var(--ok)}
.opt-wrong{background:var(--badbg);border-color:var(--bad)}
textarea{width:100%;border:1px solid var(--line);border-radius:8px;padding:10px;font:inherit;resize:vertical}
.question.ok{border-left:5px solid var(--ok)}
.question.bad{border-left:5px solid var(--bad)}
.feedback{margin-top:12px;padding:12px;background:#fafbfd;border-radius:8px;border:1px dashed var(--line)}
.feedback p{margin:6px 0}
.verdict.ok{color:var(--ok);font-weight:700}
.verdict.bad{color:var(--bad);font-weight:700}
.bar{height:8px;background:#e5e8ef;border-radius:4px;overflow:hidden;margin:6px 0}
.bar span{display:block;height:100%;background:var(--pri)}
details summary{cursor:pointer;color:var(--pri);margin-top:6px}
.summary h2{margin-top:0}