:root {
  --bg: #0b1020;
  --panel: #111827;
  --panel2: #172033;
  --text: #edf2f7;
  --muted: #9ca8bb;
  --accent: #6ee7b7;
  --accent2: #60a5fa;
  --danger: #fb7185;
  --border: #263247;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, system-ui, Arial, sans-serif;
  background: radial-gradient(circle at top, #18233d 0, var(--bg) 45%);
  color: var(--text);
}
button, input, select, textarea { font: inherit; }
button {
  border: 0;
  border-radius: 10px;
  padding: 11px 16px;
  cursor: pointer;
  background: var(--accent);
  color: #07130f;
  font-weight: 700;
}
button.secondary { background: var(--panel2); color: var(--text); border: 1px solid var(--border); }
button.danger { background: var(--danger); }
button:disabled { opacity: .45; cursor: not-allowed; }
.container { width: min(1100px, 92%); margin: auto; }
.center-screen { min-height: 100vh; display: grid; place-items: center; padding: 24px; }
.card {
  background: rgba(17,24,39,.94);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 24px;
  box-shadow: 0 18px 50px rgba(0,0,0,.25);
}
.login { width: min(430px, 100%); }
h1, h2, h3 { margin-top: 0; }
.muted { color: var(--muted); }
label { display:block; margin: 14px 0 7px; color: #cbd5e1; }
input, select, textarea {
  width: 100%;
  background: #0a0f1b;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  outline: none;
}
input:focus, select:focus, textarea:focus { border-color: var(--accent2); }
header {
  position: sticky; top: 0; z-index: 5;
  background: rgba(11,16,32,.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav { min-height: 64px; display:flex; align-items:center; justify-content:space-between; gap: 12px; }
.nav-actions { display:flex; gap:8px; flex-wrap:wrap; }
main { padding: 34px 0 60px; }
.hero { padding: 34px; margin-bottom: 22px; }
.grid { display:grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.language { transition: transform .15s, border-color .15s; }
.language:hover { transform: translateY(-3px); border-color: #3b82f6; }
.badge { display:inline-block; padding: 5px 9px; border-radius: 999px; background:#20304b; color:#bfdbfe; font-size:.82rem; }
.progress {
  height: 9px; background:#0a0f1b; border-radius:999px; overflow:hidden; margin: 10px 0 18px;
}
.progress > div { height:100%; background: linear-gradient(90deg,var(--accent2),var(--accent)); }
.lesson-list { display:grid; gap:10px; }
.lesson-row {
  display:flex; align-items:center; justify-content:space-between; gap:12px;
  padding:14px; background:var(--panel2); border:1px solid var(--border); border-radius:12px;
}
.lesson-row.locked { opacity:.5; }
.question { margin: 18px 0; padding:18px; border:1px solid var(--border); border-radius:14px; background:#0e1626; }
.option { display:block; margin:8px 0; padding:10px; border:1px solid var(--border); border-radius:10px; cursor:pointer; }
.option:hover { border-color:#3b82f6; }
.code {
  background:#070b13; color:#dbeafe; padding:18px; border-radius:12px;
  overflow:auto; border:1px solid var(--border); font-family:Consolas,monospace;
}
.editor { min-height:180px; resize:vertical; font-family:Consolas,monospace; }
.output { white-space:pre-wrap; min-height:70px; margin-top:12px; }
.notice { padding:12px 14px; border-radius:10px; background:#172554; color:#dbeafe; margin:14px 0; }
.error { background:#3f1722; color:#fecdd3; }
.success { background:#123326; color:#bbf7d0; }
.small { font-size:.9rem; }
@media (max-width:650px) {
  .hero { padding:22px; }
  .lesson-row { align-items:flex-start; flex-direction:column; }
}

.manual-note { border-left: 4px solid var(--accent); }

.admin-table { width:100%; border-collapse:collapse; }
.admin-table th, .admin-table td { padding:12px; text-align:left; border-bottom:1px solid var(--border); white-space:nowrap; }
.admin-table th { color:#cbd5e1; background:var(--panel2); }