:root {
  --bg: #09111f;
  --card: rgba(13, 22, 41, 0.78);
  --card-border: rgba(255,255,255,0.08);
  --text: #ecf3ff;
  --muted: #9aacc7;
  --accent: #75a8ff;
  --accent-2: #64f0d5;
  --danger: #ff7a9f;
  --success: #73f6a0;
  --shadow: 0 20px 60px rgba(0,0,0,0.38);
}
* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; font-family: Inter, system-ui, sans-serif; color: var(--text); background: radial-gradient(circle at top, #16294d 0%, #0a1020 45%, #060a14 100%); }
body { padding: 32px 18px; overflow-x: hidden; }
.bg-orb { position: fixed; border-radius: 999px; filter: blur(60px); opacity: 0.28; pointer-events: none; }
.orb-1 { width: 280px; height: 280px; background: #5b89ff; top: -40px; left: -20px; }
.orb-2 { width: 360px; height: 360px; background: #00d6a9; bottom: -80px; right: -60px; }
.app-shell { max-width: 1180px; margin: 0 auto; position: relative; z-index: 1; }
.topbar { display: flex; justify-content: space-between; align-items: flex-start; gap: 20px; margin-bottom: 22px; }
.eyebrow { color: var(--accent-2); letter-spacing: 0.16em; font-size: 12px; font-weight: 700; margin-bottom: 10px; }
h1 { margin: 0; font-size: clamp(36px, 6vw, 68px); line-height: 0.95; }
.subtitle { color: var(--muted); margin: 10px 0 0; font-size: 16px; }
.badge { padding: 12px 16px; border-radius: 999px; background: rgba(255,255,255,0.08); border: 1px solid rgba(255,255,255,0.12); font-weight: 600; white-space: nowrap; }
.card { background: var(--card); border: 1px solid var(--card-border); backdrop-filter: blur(14px); border-radius: 24px; box-shadow: var(--shadow); }
.controls { display: grid; grid-template-columns: repeat(3, minmax(120px, 1fr)) auto; gap: 16px; padding: 20px; align-items: end; }
.control-group { display: flex; flex-direction: column; gap: 8px; }
label { font-size: 13px; color: var(--muted); font-weight: 600; }
select, button { font: inherit; }
select { width: 100%; padding: 14px 16px; border-radius: 16px; border: 1px solid rgba(255,255,255,0.08); background: rgba(255,255,255,0.06); color: var(--text); outline: none; }
.button-row { display: flex; gap: 10px; flex-wrap: wrap; justify-content: flex-end; }
.btn { border: 0; border-radius: 16px; padding: 14px 18px; font-weight: 700; cursor: pointer; transition: .2s ease; }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn-primary { background: linear-gradient(135deg, var(--accent), #9f7cff); color: white; }
.btn-secondary { background: linear-gradient(135deg, #1de9b6, #00b8d9); color: #03111f; }
.btn-ghost { background: rgba(255,255,255,0.08); color: var(--text); border: 1px solid rgba(255,255,255,0.08); }
.btn:not(:disabled):hover { transform: translateY(-1px); filter: brightness(1.05); }
.stats-row { margin: 18px 0; display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.stat { padding: 16px 18px; display: flex; flex-direction: column; gap: 6px; }
.stat span { color: var(--muted); font-size: 13px; }
.stat strong { font-size: 28px; }
.boards { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.board { padding: 20px; }
.board-title { font-size: 18px; font-weight: 700; margin-bottom: 16px; }
.grid { display: grid; gap: 10px; aspect-ratio: 1 / 1; }
.cell { border-radius: 16px; border: 1px solid rgba(255,255,255,0.08); background: rgba(255,255,255,0.05); box-shadow: inset 0 1px 0 rgba(255,255,255,0.05); transition: .18s ease; }
.cell.active { background: linear-gradient(145deg, rgba(117,168,255,.95), rgba(100,240,213,.85)); box-shadow: 0 0 0 1px rgba(255,255,255,0.25), 0 10px 24px rgba(90,160,255,.28); }
.interactive .cell { cursor: pointer; }
.interactive .cell:hover { transform: translateY(-1px); border-color: rgba(255,255,255,0.18); }
.cell.correct { outline: 2px solid var(--success); }
.cell.wrong { outline: 2px solid var(--danger); }
.message { margin-top: 18px; padding: 18px 20px; font-size: 16px; color: var(--text); }
@media (max-width: 920px) {
  .controls { grid-template-columns: 1fr 1fr; }
  .button-row { grid-column: 1 / -1; justify-content: stretch; }
  .button-row .btn { flex: 1; }
  .boards, .stats-row { grid-template-columns: 1fr; }
  .topbar { flex-direction: column; }
}
@media (max-width: 560px) {
  body { padding: 18px 12px 32px; }
  .controls { grid-template-columns: 1fr; }
  .badge { white-space: normal; }
  .board, .controls, .message, .stat { border-radius: 20px; }
}