:root {
  --bg: #0f172a;
  --panel: rgba(255, 255, 255, 0.08);
  --panel-border: rgba(255, 255, 255, 0.12);
  --text: #f8fafc;
  --muted: #cbd5e1;
  --accent: #38bdf8;
  --accent-2: #22c55e;
  --shadow: 0 20px 40px rgba(0, 0, 0, 0.25);
  --card-front: linear-gradient(135deg, #38bdf8, #2563eb);
  --card-back: linear-gradient(135deg, #1e293b, #334155);
  --matched: linear-gradient(135deg, #22c55e, #16a34a);
}

body.light {
  --bg: #f1f5f9;
  --panel: rgba(255, 255, 255, 0.9);
  --panel-border: rgba(15, 23, 42, 0.08);
  --text: #0f172a;
  --muted: #475569;
  --accent: #0ea5e9;
  --accent-2: #16a34a;
  --shadow: 0 16px 30px rgba(15, 23, 42, 0.08);
  --card-front: linear-gradient(135deg, #0ea5e9, #2563eb);
  --card-back: linear-gradient(135deg, #cbd5e1, #94a3b8);
  --matched: linear-gradient(135deg, #22c55e, #15803d);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: radial-gradient(circle at top, rgba(56, 189, 248, 0.18), transparent 30%),
    var(--bg);
  color: var(--text);
  min-height: 100%;
}

body {
  min-height: 100vh;
}

.app {
  width: min(1100px, 92%);
  margin: 0 auto;
  padding: 24px 0 40px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 24px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.topbar h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
}

.subtitle {
  margin: 10px 0 0;
  color: var(--muted);
  max-width: 700px;
  line-height: 1.6;
}

.theme-btn {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  color: var(--text);
  width: 52px;
  height: 52px;
  border-radius: 14px;
  cursor: pointer;
  font-size: 1.2rem;
  box-shadow: var(--shadow);
}

.game-panel {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-bottom: 24px;
}

.stat-card,
.restart-btn {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.stat-card {
  padding: 18px;
}

.stat-card .label {
  display: block;
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 6px;
}

.stat-card strong {
  font-size: 1.5rem;
}

.restart-btn {
  border: none;
  color: white;
  background: linear-gradient(135deg, var(--accent), #2563eb);
  font-size: 1rem;
  font-weight: 700;
  padding: 0 20px;
  min-height: 70px;
  cursor: pointer;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.restart-btn:hover {
  transform: translateY(-2px);
  opacity: 0.95;
}

.board-wrap {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 18px;
}

.game-board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}

.card {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  border: none;
  background: transparent;
  cursor: pointer;
  perspective: 1000px;
  padding: 0;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  border-radius: 18px;
  transition: transform 0.5s ease;
  transform-style: preserve-3d;
}

.card.flipped .card-inner,
.card.matched .card-inner {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  backface-visibility: hidden;
  user-select: none;
}

.card-front {
  background: var(--card-front);
  color: white;
  transform: rotateY(180deg);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.12);
}

.card-back {
  background: var(--card-back);
  color: white;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.08);
}

.card.matched .card-front {
  background: var(--matched);
}

.modal {
  position: fixed;
  inset: 0;
  background: rgba(2, 6, 23, 0.68);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal.hidden {
  display: none;
}

.modal-content {
  width: min(420px, 100%);
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 28px;
  text-align: center;
}

.modal-content h2 {
  margin-top: 0;
  margin-bottom: 10px;
}

.modal-content p {
  color: var(--muted);
  margin-bottom: 20px;
  line-height: 1.6;
}

@media (max-width: 900px) {
  .game-panel {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .app {
    width: min(96%, 96%);
    padding-top: 16px;
  }

  .topbar {
    align-items: center;
  }

  .topbar h1 {
    font-size: 1.8rem;
  }

  .subtitle {
    font-size: 0.95rem;
  }

  .game-board {
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
  }

  .board-wrap {
    padding: 12px;
    border-radius: 18px;
  }

  .card-face {
    border-radius: 14px;
    font-size: 1.5rem;
  }

  .stat-card {
    padding: 14px;
  }

  .restart-btn {
    min-height: 58px;
  }
}

@media (max-width: 420px) {
  .game-panel {
    grid-template-columns: 1fr;
  }

  .game-board {
    gap: 8px;
  }

  .card-face {
    font-size: 1.25rem;
  }
}