/* ===================================
   2048 Cupcakes - Dark Mode & Theme Toggle
   =================================== */

/* CSS Custom Properties for Light/Dark Themes */
:root {
  /* Light Theme (Default) */
  --bg-primary: #ffffff;
  --bg-secondary: #faf8ef;
  --bg-game: #f67098;
  --text-primary: #4d2523;
  --text-secondary: #776e65;
  --text-muted: #8f7a66;
  --border-accent: #f2b179;
  --button-bg: #f888a9;
  --button-text: #3c1b1a;
  --shadow-color: rgba(0, 0, 0, 0.05);
  --grid-cell-bg: rgba(255, 255, 255, 0.35);
  --hr-color: #fbb8cc;
  --overlay-bg: rgba(255, 255, 255, 0.7);
  --card-bg: #fdfae8;
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: #1a1a2e;
  --bg-secondary: #16213e;
  --bg-game: #4a1942;
  --text-primary: #e8e8e8;
  --text-secondary: #b8b8b8;
  --text-muted: #888888;
  --border-accent: #f2b179;
  --button-bg: #6b3a5b;
  --button-text: #ffffff;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --grid-cell-bg: rgba(255, 255, 255, 0.15);
  --hr-color: #4a1942;
  --overlay-bg: rgba(26, 26, 46, 0.85);
  --card-bg: #1e2a4a;
}

/* Apply theme variables */
[data-theme="dark"] html,
[data-theme="dark"] body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

[data-theme="dark"] body {
  background-image: none;
}

[data-theme="dark"] .global-header {
  background: var(--bg-secondary);
  border-bottom-color: var(--border-accent);
  box-shadow: 0 2px 10px var(--shadow-color);
}

[data-theme="dark"] .header-content .brand a,
[data-theme="dark"] .header-content nav a {
  color: var(--text-secondary);
}

[data-theme="dark"] .header-content nav a:hover {
  background: var(--border-accent);
  color: var(--bg-primary);
}

[data-theme="dark"] .game-container {
  background: var(--bg-game);
}

[data-theme="dark"] .grid-cell {
  background: var(--grid-cell-bg);
}

[data-theme="dark"] .game-container .game-message {
  background: var(--overlay-bg);
}

[data-theme="dark"] hr {
  border-bottom-color: var(--hr-color);
}

[data-theme="dark"] .restart-button,
[data-theme="dark"] .game-container .game-message a {
  background: var(--button-bg);
  color: var(--button-text);
}

[data-theme="dark"] a {
  color: var(--border-accent);
}

[data-theme="dark"] .score-container,
[data-theme="dark"] .best-container {
  background: var(--bg-game);
}

[data-theme="dark"] .dropdown-content {
  background: var(--bg-secondary);
}

[data-theme="dark"] .dropdown-content a {
  color: var(--text-secondary);
}

[data-theme="dark"] .dropdown-content a:hover {
  background: var(--bg-game);
  color: var(--text-primary);
}

[data-theme="dark"] footer {
  background: var(--bg-secondary);
  border-top-color: var(--border-accent);
}

/* Theme Toggle Button */
.theme-toggle {
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  border: none;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  font-size: 24px;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
  transition: all 0.3s ease;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  position: absolute;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

[data-theme="dark"] .theme-toggle .icon-sun {
  opacity: 1;
  transform: rotate(0deg);
}

[data-theme="dark"] .theme-toggle .icon-moon {
  opacity: 0;
  transform: rotate(90deg);
}

.theme-toggle .icon-sun {
  opacity: 0;
  transform: rotate(-90deg);
}

.theme-toggle .icon-moon {
  opacity: 1;
  transform: rotate(0deg);
}

/* Smooth transition for theme change */
body,
.global-header,
.game-container,
.grid-cell,
.restart-button,
footer,
.dropdown-content {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}