:root{
  --bg:#0b0b0c; --card:#15161a; --text:#e9eef5; --muted:#a0a6b2;
  --brand:#19B246; --warn:#F5C638; --radius:18px; --shadow:0 8px 24px rgba(0,0,0,.35);
}
*{box-sizing:border-box; -webkit-tap-highlight-color: transparent;}
html,body{margin:0;padding:0;background:var(--bg);color:var(--text);font:16px/1.4 system-ui,-apple-system,Segoe UI,Roboto,Inter,Arial}
.topbar{position:sticky;top:0;z-index:10;background:linear-gradient(180deg,rgba(0,0,0,.6),transparent);backdrop-filter:saturate(150%) blur(6px);padding:12px 16px}
h1{margin:0;font-size:20px;letter-spacing:.3px}
main{max-width:900px;margin:10px auto;padding:8px}
.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:16px;margin:12px 8px}
h2{margin:0 0 10px 0;font-size:18px}
.controls{display:grid;gap:10px;margin-top:12px}
.small{font-size:13px}
.row{display:flex;align-items:center;gap:10px;justify-content:space-between}
.subject-grid{display:grid;gap:10px;grid-template-columns:repeat(2,1fr)}
@media (min-width:700px){.subject-grid{grid-template-columns:repeat(3,1fr)}}
.subject{border:1px solid #2a2d34;border-radius:14px;padding:10px;display:flex;align-items:center;justify-content:space-between}
.badge{display:inline-block;background:#24262c;color:#cfd5df;border:1px solid #2a2d34;border-radius:999px;padding:4px 10px;font-size:12px}
.btn{appearance:none;border:1px solid #2a2d34;background:#22262d;color:var(--text);padding:10px 14px;border-radius:12px;cursor:pointer}
.btn:active{transform:translateY(1px)}
.btn.primary{background:var(--brand);border-color:transparent;color:#07130a;font-weight:600}
.btn.warn{background:var(--warn);color:#1d1500;border-color:transparent}
.hidden{display:none}
.muted{color:var(--muted)}
.question{font-size:18px;margin:10px 0 12px}
.options{display:grid;gap:8px}
.option{border:1px solid #2a2d34;border-radius:12px;padding:10px;display:flex;align-items:flex-start;gap:8px}
.option.correct{border-color:#1f9d50;background:rgba(25,178,70,.08)}
.option.incorrect{border-color:#b21919;background:rgba(220,60,60,.08)}
.optlabel{display:block}
.nav{display:flex;gap:10px;margin-top:12px;justify-content:space-between}
.footer{opacity:.7;text-align:center;padding:20px 10px}
button{touch-action:manipulation}
.qimg{max-width:100%; height:auto; display:block; margin:8px 0; border-radius:10px; border:1px solid #2a2d34}
.img-wrap{margin:6px 0 10px}
.code{font-family:ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace}