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

:root {
  --bg-page: #1a1a2e;
  --bg-card: #16213e;
  --accent: #e94560;
  --accent-hover: #ff6b6b;
  --text: #eee;
  --text-muted: #a0a0a0;
  --square-light: #f0d9b5;
  --square-dark: #b58863;
  --square-highlight: rgba(255, 255, 0, 0.4);
  --square-move: rgba(0, 128, 0, 0.35);
  --square-check: rgba(200, 0, 0, 0.5);
}

body {
  font-family: "Outfit", sans-serif;
  background: var(--bg-page);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.wrapper {
  width: 100%;
  max-width: 600px;
  padding: 1rem;
}

.hidden {
  display: none !important;
}

/* ----- Mode selection ----- */
.mode-screen {
  text-align: center;
  padding: 2rem 1rem;
}

.mode-screen h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.mode-screen p {
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.mode-buttons {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 280px;
  margin: 0 auto;
}

.mode-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  font-family: inherit;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  background: var(--bg-card);
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s, transform 0.15s;
}

.mode-btn:hover {
  background: rgba(233, 69, 96, 0.2);
  border-color: var(--accent);
  transform: translateY(-2px);
}

.mode-icon {
  font-size: 1.5rem;
}

/* ----- Game screen ----- */
.game-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.game-screen .header {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.game-screen .header h1 {
  font-size: 1.5rem;
  font-weight: 700;
}

.game-info {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.turn-label {
  font-weight: 600;
  color: var(--text);
}

.mode-badge {
  font-size: 0.85rem;
  color: var(--text-muted);
  background: rgba(255, 255, 255, 0.08);
  padding: 0.25rem 0.5rem;
  border-radius: 6px;
}

.btn {
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.5rem 1rem;
  color: var(--text);
  background: var(--accent);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s;
}

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

.btn-ghost {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.25);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.4);
}

.btn-large {
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  margin-top: 0.5rem;
}

/* ----- Board ----- */
.game-container {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

.board {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  width: min(90vw, 480px);
  height: min(90vw, 480px);
  max-width: 480px;
  max-height: 480px;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

.square {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(1.5rem, 5vw, 2.75rem);
  cursor: pointer;
  user-select: none;
  transition: background 0.1s;
}

.square.light {
  background: var(--square-light);
  color: #333;
}

.square.dark {
  background: var(--square-dark);
  color: #1a1a1a;
}

.square.highlight {
  background: var(--square-highlight) !important;
}

.square.move-target {
  background: var(--square-move) !important;
  cursor: pointer;
}

.square.check {
  background: var(--square-check) !important;
}

.square.last-move {
  outline: 2px solid rgba(255, 200, 0, 0.8);
  outline-offset: -2px;
}

.square.dragging {
  opacity: 0.85;
}

/* ----- Promotion overlay ----- */
.promotion-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border-radius: 8px;
  z-index: 10;
}

.promotion-overlay p {
  font-size: 0.95rem;
  color: var(--text-muted);
}

.promotion-pieces {
  display: flex;
  gap: 0.5rem;
}

.promotion-piece-btn {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  background: var(--bg-card);
  border: 2px solid rgba(255, 255, 255, 0.2);
  border-radius: 8px;
  color: var(--text);
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}

.promotion-piece-btn:hover {
  background: var(--accent);
  border-color: var(--accent);
}

/* ----- Game over overlay ----- */
.game-over-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 20;
  padding: 1rem;
}

.game-over-box {
  background: var(--bg-card);
  padding: 2rem;
  border-radius: 16px;
  text-align: center;
  max-width: 340px;
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.game-over-box h2 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.game-over-box p {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

/* ----- Responsive ----- */
@media (max-width: 520px) {
  .wrapper {
    padding: 0.75rem;
  }

  .board {
    width: min(95vw, 360px);
    height: min(95vw, 360px);
    min-width: 280px;
    min-height: 280px;
  }

  .square {
    font-size: clamp(1.25rem, 4.5vw, 2rem);
  }

  .game-screen .header h1 {
    font-size: 1.25rem;
  }

  .turn-label {
    font-size: 0.9rem;
  }

  .btn,
  .btn-ghost {
    padding: 0.45rem 0.75rem;
    font-size: 0.85rem;
  }

  .game-over-box {
    padding: 1.5rem;
    margin: 0.5rem;
  }

  .game-over-box h2 {
    font-size: 1.25rem;
  }

  .promotion-piece-btn {
    width: 44px;
    height: 44px;
    font-size: 1.75rem;
  }
}

/* Very small phones & safe areas */
@media (max-width: 380px) {
  .wrapper {
    padding: 0.5rem;
    padding-left: max(0.5rem, env(safe-area-inset-left));
    padding-right: max(0.5rem, env(safe-area-inset-right));
    padding-bottom: max(0.5rem, env(safe-area-inset-bottom));
  }

  .mode-screen {
    padding: 1.25rem 0.5rem;
  }

  .mode-screen h1 {
    font-size: 1.75rem;
  }

  .mode-screen p {
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
  }

  .mode-btn {
    padding: 0.85rem 1rem;
    font-size: 1rem;
  }

  .game-info {
    gap: 0.5rem;
  }

  .mode-badge {
    font-size: 0.75rem;
    padding: 0.2rem 0.4rem;
  }

  .board {
    width: min(100vw - 1rem, 320px);
    height: min(100vw - 1rem, 320px);
    min-width: 256px;
    min-height: 256px;
  }

  .square {
    font-size: clamp(1rem, 3.5vw, 1.5rem);
  }
}

/* Safe area for notched devices (all viewports) */
@supports (padding: env(safe-area-inset-top)) {
  body {
    padding-top: env(safe-area-inset-top);
    padding-bottom: env(safe-area-inset-bottom);
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
  }
}