:root{
  --bg:#0b0f16; --card:#121826; --muted:#9aa4b2; --text:#e5e7eb;
  --accent:#4f46e5; --ok:#16a34a; --bad:#ef4444; --btn:#1f2937;
  --btn-hover:#374151; --border:#243041;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0; font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC",sans-serif;
  background:linear-gradient(180deg,#090d13,#0e1522 30%,#0b1220);
  color:var(--text); line-height:1.6;
}
.container{max-width:920px;margin:0 auto;padding:24px}
.card{
  background:linear-gradient(180deg,rgba(255,255,255,.04),rgba(255,255,255,.02));
  border:1px solid var(--border); border-radius:16px; padding:24px;
  box-shadow:0 10px 40px rgba(0,0,0,.35); backdrop-filter:blur(6px)
}
h1{font-size:28px;margin:6px 0 18px 0}
.muted{color:var(--muted)} .spacer{height:12px}
.btn{
  appearance:none;border:1px solid var(--border);background:var(--btn);color:var(--text);
  border-radius:12px;padding:12px 16px;cursor:pointer;transition:.15s; font-size:15px
}
.btn:hover{background:var(--btn-hover)}
.btn.primary{background:var(--accent);border-color:#3f3abf}
.btn.primary:hover{filter:brightness(1.05)}
.btn.ghost{background:transparent}
.btn:disabled{opacity:.5;cursor:not-allowed}
.home-actions{display:flex;gap:12px;flex-wrap:wrap}
.home-actions .btn{font-size:16px;padding:14px 18px}
.info{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.badge{font-size:12px;padding:4px 8px;border:1px solid var(--border);border-radius:999px;color:var(--muted)}
.src{word-break:break-all;color:#c7d2fe}
.source-panel{margin-top:12px;padding:12px;border:1px solid var(--border);border-radius:12px;background:rgba(255,255,255,.02)}
.panel-header{display:flex;align-items:center;gap:8px;margin-bottom:10px}
.source-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.source-item{display:flex;flex-direction:column;gap:6px;padding:10px 12px;border:1px solid var(--border);border-radius:10px;background:rgba(11,18,32,.6)}
.source-title{display:flex;align-items:center;gap:10px;font-weight:600}
.source-item input[type=radio]{accent-color:var(--accent);cursor:pointer}
.source-label{font-size:15px}
.footer-note.compact{margin-top:8px}

.quiz-header{display:flex;align-items:center;justify-content:space-between;gap:12px}
.mode-badge{font-size:13px;padding:6px 10px;border:1px solid var(--border);background:rgba(79,70,229,.15);border-radius:999px}
.progress{font-size:13px;color:var(--muted)}
.prompt{margin-top:16px;font-size:20px;padding:16px;border:1px dashed var(--border);border-radius:12px;background:rgba(255,255,255,.02)}
.answer-row{display:flex;gap:10px;margin-top:16px}
.answer-input{
  flex:1;padding:12px 14px;border-radius:12px;border:1px solid var(--border);
  background:rgba(8,12,20,.7);color:var(--text);font-size:16px;outline:none;transition:.15s
}
.answer-input:focus{border-color:#4c5a71;box-shadow:0 0 0 3px rgba(79,70,229,.15)}
.answer-input.ok{border-color:var(--ok);box-shadow:0 0 0 3px rgba(22,163,74,.25)}
.answer-input.bad{border-color:var(--bad);box-shadow:0 0 0 3px rgba(239,68,68,.25)}
.feedback{min-height:24px;margin-top:8px;font-size:14px}
.feedback.ok{color:var(--ok)} .feedback.bad{color:var(--bad)}
.nav-row{display:flex;gap:10px;margin-top:10px}
.answer-key{margin-top:6px;color:var(--bad)}
.footer-note{margin-top:18px;color:var(--muted);font-size:12px}
.view{display:none}.view.active{display:block}
@media (max-width:740px){.source-list{grid-template-columns:1fr}}
@media (max-width:520px){.answer-row{flex-direction:column}}