*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #0a0e17;
  --surface: #131a2b;
  --card-bg: #1c2541;
  --card-face: #1e3a5f;
  --accent: #00e5ff;
  --accent-dim: #007a8a;
  --success: #00e676;
  --danger: #ff1744;
  --text: #e0e6ed;
  --text-dim: #7a8ba5;
  --matched: #1b5e20;
  --radius: 8px;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}

#app {
  max-width: 1400px;
  margin: 0 auto;
  padding: 12px 16px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  text-align: center;
  margin-bottom: 12px;
  flex-shrink: 0;
}

header h1 {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.accent {
  color: var(--accent);
}

#game-info {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
}

.info-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--surface);
  padding: 6px 18px;
  border-radius: var(--radius);
  min-width: 80px;
}

.info-item .label {
  font-size: 0.7rem;
  text-transform: uppercase;
  color: var(--text-dim);
  letter-spacing: 1px;
}

.info-item .value {
  font-size: 1.2rem;
  font-weight: 700;
}

.timer-box .value {
  color: var(--accent);
}

.timer-box.warning .value {
  color: var(--danger);
  animation: pulse 0.5s ease-in-out infinite alternate;
}

@keyframes pulse {
  from { opacity: 1; }
  to { opacity: 0.5; }
}

.screen {
  display: none;
  flex: 1;
  flex-direction: column;
}

.screen.active {
  display: flex;
}

.screen-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1;
  text-align: center;
  padding: 20px;
}

.screen-content h2 {
  font-size: 2rem;
  margin-bottom: 16px;
  color: var(--accent);
}

.screen-content p {
  font-size: 1.1rem;
  color: var(--text-dim);
  margin-bottom: 20px;
  max-width: 500px;
}

.rules {
  list-style: none;
  margin-bottom: 30px;
  text-align: left;
}

.rules li {
  padding: 6px 0;
  color: var(--text-dim);
  font-size: 0.95rem;
}

.rules li::before {
  content: '▸ ';
  color: var(--accent);
  font-weight: bold;
}

.btn-primary {
  background: var(--accent);
  color: var(--bg);
  border: none;
  padding: 14px 40px;
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: var(--radius);
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 2px;
  transition: transform 0.15s, box-shadow 0.15s;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 229, 255, 0.3);
}

.btn-link {
  display: inline-block;
  margin-top: 16px;
  padding: 12px 32px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent);
  border: 2px solid var(--accent-dim);
  border-radius: var(--radius);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.btn-link:hover {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}

.btn-accent {
  background: transparent;
  color: var(--accent);
  border: 2px solid var(--accent);
  padding: 8px 24px;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius);
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: background 0.2s, color 0.2s;
}

.btn-accent:hover {
  background: var(--accent);
  color: var(--bg);
}

.phase-banner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 10px;
  background: var(--surface);
  border-radius: var(--radius);
  margin-bottom: 12px;
  font-size: 1.1rem;
  font-weight: 600;
  flex-shrink: 0;
}

.card-grid {
  display: grid;
  justify-content: center;
  align-content: start;
  flex: 1;
  padding: 4px;
  overflow: hidden;
}

.card {
  position: relative;
  cursor: pointer;
  perspective: 600px;
  aspect-ratio: 1;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.1s ease;
  transform-style: preserve-3d;
}

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

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: var(--radius);
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.card-back {
  background: var(--card-bg);
  border: 2px solid var(--accent-dim);
}

.card-back::after {
  content: '?';
  font-size: inherit;
  color: var(--accent-dim);
}

.card-front {
  background: var(--card-face);
  transform: rotateY(180deg);
  color: var(--text);
  border: 2px solid var(--accent);
}

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

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

.card.matched {
  cursor: default;
}

@media (max-width: 600px) {
  header h1 {
    font-size: 1.2rem;
  }

  #game-info {
    gap: 8px;
  }

  .info-item {
    padding: 4px 10px;
    min-width: 60px;
  }

  .info-item .value {
    font-size: 1rem;
  }

  .phase-banner {
    font-size: 0.9rem;
    flex-direction: column;
    gap: 8px;
  }

}