:root {
  --color-bg: #ecfdf5;
  --color-surface: #ffffff;
  --color-ink: #064e3b;
  --color-accent: #047857;
  --color-accent-dark: #065f46;
  --color-card-back: #0f766e;
  --color-card-face: #f0fdf4;
  --color-matched: #bbf7d0;
  --color-border: #6ee7b7;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 24px 16px;
  background: var(--color-bg);
  color: var(--color-ink);
  font-family: Georgia, "Times New Roman", serif;
}

.page {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
}

.hero {
  margin: 0 0 20px;
  padding: 24px;
  background: var(--color-accent);
  color: #ecfdf5;
  border-radius: 16px;
  text-align: center;
}

.hero h1,
.hero p {
  margin: 0 0 8px;
}

.hud {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  margin: 0 0 16px;
  padding: 14px 16px;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: 12px;
}

.hud p {
  margin: 0;
  font-weight: 700;
}

button {
  padding: 10px 16px;
  border: 0;
  border-radius: 8px;
  background: var(--color-accent-dark);
  color: #ecfdf5;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  transition: background-color 160ms ease, transform 160ms ease;
}

button:hover,
button:focus-visible {
  background: var(--color-accent);
  transform: translateY(-1px);
}

.status {
  margin: 0 0 16px;
  padding: 12px 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  font-weight: 700;
}

.board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.card {
  min-height: 96px;
  padding: 12px;
  border: 2px solid var(--color-accent-dark);
  border-radius: 12px;
  background: var(--color-card-back);
  color: #ecfdf5;
  font-size: 18px;
  font-weight: 700;
  cursor: pointer;
  transition: transform 180ms ease, background-color 180ms ease;
}

.card:hover,
.card:focus-visible {
  transform: scale(1.03);
}

.card.is-flipped,
.card.is-matched {
  background: var(--color-card-face);
  color: var(--color-ink);
}

.card.is-matched {
  background: var(--color-matched);
  cursor: default;
}

.card-label {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 72px;
  text-align: center;
}

@media (max-width: 560px) {
  .board {
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
  }

  .card {
    min-height: 84px;
    font-size: 15px;
  }
}

@media (prefers-reduced-motion: reduce) {
  button,
  .card {
    transition-duration: 0.01ms;
  }
}