:root{
  --bg:#0d0f14; --panel:#161922; --panel-2:#1c2029; --line:#272d3a;
  --text:#eef1f6; --muted:#98a2b3;
  --accent:#5b8cff; --accent-2:#3a6bdb; --ok:#1f9d6b; --no:#d8503f;
  --radius:16px; --maxw:880px;
  --shadow:0 1px 0 rgba(255,255,255,.02), 0 12px 30px -20px rgba(0,0,0,.7);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:
    radial-gradient(1200px 600px at 70% -200px, rgba(91,140,255,.08), transparent 60%),
    var(--bg);
  color:var(--text);line-height:1.65;
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.muted{color:var(--muted)}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:6px}

/* ---------- Header / Nav ---------- */
.topbar{position:sticky;top:0;z-index:50;display:flex;align-items:center;
  justify-content:space-between;gap:1rem;padding:.7rem 1.1rem;
  border-bottom:1px solid var(--line);
  background:rgba(13,15,20,.72);backdrop-filter:saturate(160%) blur(10px)}
.brand{display:inline-flex;align-items:center;gap:.5rem;font-weight:800;
  font-size:1.18rem;letter-spacing:-.02em;color:var(--text)}
.brand:hover{text-decoration:none}
.brand .mark{display:grid;place-items:center;width:1.7rem;height:1.7rem;border-radius:8px;
  background:linear-gradient(135deg,var(--accent),var(--accent-2));color:#fff;
  font-size:.85rem;font-weight:800}
.brand span{color:var(--accent)}
.topbar nav{display:flex;gap:.2rem;flex-wrap:wrap;align-items:center}
.topbar nav a{color:var(--muted);font-size:.93rem;font-weight:600;
  padding:.4rem .7rem;border-radius:9px;transition:color .15s,background .15s}
.topbar nav a:hover{color:var(--text);background:rgba(255,255,255,.05);text-decoration:none}
.topbar nav a.active{color:#fff;background:rgba(91,140,255,.16)}
.topbar nav a.logout{color:var(--muted)}

/* ---------- Layout ---------- */
.wrap{max-width:var(--maxw);margin:2.2rem auto 3rem;padding:0 1.1rem}
h1{font-size:1.8rem;font-weight:800;letter-spacing:-.025em;margin:.2rem 0 1rem;line-height:1.2}
h2{font-size:1.18rem;font-weight:700;letter-spacing:-.01em;margin:1.6rem 0 .5rem}
p{margin:.5rem 0}

/* ---------- Cards ---------- */
.card{background:linear-gradient(180deg,var(--panel),var(--panel) 60%, #14171f);
  border:1px solid var(--line);border-radius:var(--radius);
  padding:1.25rem 1.35rem;margin:1rem 0;box-shadow:var(--shadow)}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:1rem}
@media(max-width:560px){.grid{grid-template-columns:1fr}}
.stat .num{font-size:2.4rem;font-weight:800;line-height:1;font-variant-numeric:tabular-nums}
.stat .lbl{color:var(--muted);margin:.2rem 0 .8rem}

/* ---------- Buttons ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;
  background:var(--accent);color:#fff;border:0;border-radius:999px;
  padding:.62rem 1.25rem;font-weight:700;font-size:.98rem;cursor:pointer;
  box-shadow:0 6px 16px -8px rgba(91,140,255,.7);
  transition:transform .12s ease,background .15s ease,box-shadow .15s ease}
.btn:hover{background:var(--accent-2);text-decoration:none;transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn.ghost{background:transparent;border:1px solid var(--line);color:var(--text);box-shadow:none}
.btn.ghost:hover{background:rgba(255,255,255,.05);border-color:var(--accent)}

/* ---------- Forms ---------- */
.form label{display:block;margin:.8rem 0 .2rem;font-weight:600;font-size:.92rem}
.form input{display:block;width:100%;margin-top:.25rem;padding:.7rem .8rem;
  background:#10131a;border:1px solid var(--line);border-radius:11px;
  color:var(--text);font-size:1rem;transition:border-color .15s,box-shadow .15s}
.form input:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(91,140,255,.18);outline:none}
.form button,.quiz button{margin-top:1.1rem}
.alert{background:rgba(216,80,63,.14);border:1px solid var(--no);
  padding:.75rem 1rem;border-radius:11px}

/* ---------- Flashcards ---------- */
.flashcard .fc-q{font-size:1.35rem;font-weight:700;letter-spacing:-.01em}
.flashcard .fc-a{font-size:1.18rem}
.grades{display:flex;gap:.5rem;flex-wrap:wrap;margin-top:.7rem}
.grade{border:0;border-radius:11px;padding:.6rem 1rem;font-weight:700;cursor:pointer;color:#fff;
  transition:transform .1s,filter .15s}
.grade:hover{filter:brightness(1.08);transform:translateY(-1px)}
.g0{background:var(--no)}.g3{background:#b9772a}.g4{background:#2f8f5b}.g5{background:#1f9d6b}
.src{color:var(--muted);font-size:.85rem}

/* ---------- Quiz options ---------- */
.opt{display:flex;gap:.7rem;align-items:flex-start;padding:.7rem .85rem;cursor:pointer;
  border:1px solid var(--line);border-radius:12px;margin:.45rem 0;
  background:#12151d;transition:border-color .15s,background .15s}
.opt:hover{border-color:var(--accent-2);background:var(--panel-2)}
.opt input{margin-top:.25rem;accent-color:var(--accent)}
.opt:has(input:checked){border-color:var(--accent);background:rgba(91,140,255,.10)}
.quiz .prompt{font-size:1.2rem;font-weight:700;letter-spacing:-.01em;margin:.2rem 0 .9rem}
.quiz .cat{font-size:.82rem;text-transform:uppercase;letter-spacing:.06em}

/* ---------- Answer feedback ---------- */
.answer{position:relative}
.answer.ok{border-color:var(--ok);background:linear-gradient(180deg,rgba(31,157,107,.08),transparent)}
.answer.no{border-color:var(--no);background:linear-gradient(180deg,rgba(216,80,63,.08),transparent)}
.verdict{font-weight:800;font-size:1.12rem;margin:.1rem 0 .4rem}
.answer.ok .verdict{color:#43d39e}.answer.no .verdict{color:#ff7a68}
.expl{margin:.45rem 0}

/* ---------- Legal / Footer ---------- */
.legal h2{font-size:1.02rem}
.foot{max-width:var(--maxw);margin:1rem auto 2rem;padding:1.3rem 1.1rem;
  color:var(--muted);border-top:1px solid var(--line);font-size:.9rem}
.foot a{color:var(--muted)}.foot a:hover{color:var(--text)}

@media(prefers-reduced-motion:reduce){*{transition:none!important}}