:root {
  --color-bg: #f0ece3;
  --color-card-back: #2c3e50;
  --color-card-front: #ffffff;
  --color-accent: #2a9d8f;
  --color-accent-glow: rgba(42, 157, 143, 0.4);
  --color-text: #2c3e50;
  --color-text-light: #6c757d;
  --color-star: #e9c46a;
  --color-star-empty: #ccc;
  --color-modal-bg: rgba(0, 0, 0, 0.6);
  --card-size: 120px;
  --card-gap: 12px;
  --flip-duration: 0.5s;
  --border-radius: 10px;
  --spacing: 16px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {
  padding: var(--spacing) 0;
}

h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing);
  padding: 0 var(--spacing) var(--spacing);
}

/* --- Stats bar --- */
.stats-bar {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
  justify-content: center;
}

.stat {
  font-size: 1.1rem;
  font-weight: 500;
}

.stat-label {
  color: var(--color-text-light);
}

#timer {
  font-variant-numeric: tabular-nums;
}

.star {
  font-size: 1.3rem;
  color: var(--color-star);
  transition: color 0.3s;
}

.star.empty {
  color: var(--color-star-empty);
}

#new-game-btn,
#play-again-btn {
  padding: 8px 20px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--border-radius);
  background-color: var(--color-accent);
  color: #fff;
  cursor: pointer;
  transition: opacity 0.2s;
}

#new-game-btn:hover,
#play-again-btn:hover {
  opacity: 0.85;
}

/* --- Settings button --- */
#settings-btn {
  padding: 8px 16px;
  font-size: 1rem;
  font-weight: 600;
  border: 2px solid var(--color-accent);
  border-radius: var(--border-radius);
  background: transparent;
  color: var(--color-accent);
  cursor: pointer;
  transition: background-color 0.2s, color 0.2s;
}

#settings-btn:hover,
#settings-btn[aria-expanded="true"] {
  background-color: var(--color-accent);
  color: #fff;
}

/* --- Settings panel --- */
.settings-panel {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  background: #fff;
  border-radius: var(--border-radius);
  padding: 16px 24px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
}

.settings-panel[hidden] {
  display: none;
}

.settings-row {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.95rem;
  font-weight: 500;
}

.settings-row label {
  color: var(--color-text);
  white-space: nowrap;
}

.settings-row input[type="color"] {
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 6px;
  padding: 2px;
  cursor: pointer;
  background: transparent;
}

/* --- Card grid --- */
#card-grid {
  display: grid;
  grid-template-columns: repeat(4, var(--card-size));
  gap: var(--card-gap);
  perspective: 1000px;
}

/* --- Card --- */
.card {
  width: var(--card-size);
  height: var(--card-size);
  cursor: pointer;
  position: relative;
}

.card-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--flip-duration) ease;
}

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

.card-face {
  position: absolute;
  inset: 0;
  border-radius: var(--border-radius);
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Back face — dark with diagonal stripe pattern + ❓ */
.card-back {
  background-color: var(--color-card-back);
  /* Diagonal stripe pattern */
  background-image: repeating-linear-gradient(
    45deg,
    transparent,
    transparent 10px,
    rgba(255, 255, 255, 0.04) 10px,
    rgba(255, 255, 255, 0.04) 20px
  );
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  font-size: 2rem;
  color: rgba(255, 255, 255, 0.25);
}

.card-back::after {
  content: '❓';
}

/* Front face — white with emoji */
.card-front {
  background-color: var(--color-card-front);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  transform: rotateY(180deg);
  font-size: 2.5rem;
}

/* Matched state */
.card.matched .card-front {
  background-color: var(--color-accent);
  box-shadow: 0 0 12px var(--color-accent-glow);
}

.card.matched {
  cursor: default;
}

/* --- Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-modal-bg);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-overlay[hidden] {
  display: none;
}

.modal-content {
  background: #fff;
  border-radius: calc(var(--border-radius) * 2);
  padding: 40px;
  text-align: center;
  max-width: 360px;
  width: 90%;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}

.modal-content h2 {
  margin-bottom: 16px;
  font-size: 1.6rem;
}

#modal-stats {
  margin-bottom: 24px;
  line-height: 1.8;
  font-size: 1.05rem;
  color: var(--color-text-light);
}

/* --- Responsive --- */
@media (max-width: 600px) {
  :root {
    --card-size: 90px;
    --card-gap: 10px;
  }

  h1 {
    font-size: 1.5rem;
  }

  .card-front {
    font-size: 2rem;
  }

  .card-back {
    font-size: 1.5rem;
  }
}

@media (max-width: 400px) {
  :root {
    --card-size: 72px;
    --card-gap: 8px;
  }

  .stats-bar {
    gap: 12px;
  }

  .card-front {
    font-size: 1.6rem;
  }
}