/* ================= THEME VARIABLES ================= */

:root {
  /* Dark Mode Colors (Default) */
  --bg-top: #081026;
  --bg-bottom: #071428;
  --panel: #0f1724;
  --text: #e6eef8;
  --text-secondary: #f6fbff;
  --text-accent: #9fb0d9;
  --muted: #9aa6bf;
  --button: #1b2430;
  --button-hover: #2a3a50;
  --border: rgba(100, 150, 255, 0.3);
  --canvas: #0b1220;
  --grid: rgba(255, 255, 255, 0.05);
  --grid-dark: rgba(0, 0, 0, 0.2);
  --shadow: rgba(2, 6, 23, 0.6);
  --modal-bg: rgba(30, 50, 80, 0.95);
  --modal-border: rgba(100, 150, 255, 0.4);
  
  /* Accent Colors (Theme-Independent) */
  --accent-primary: #4D96FF;
  --accent-success: #6BCB77;
  --accent-error: #ff6b6b;
}

body.light {
  --bg-top: #ffffff;
  --bg-bottom: #e8e8e8;
  --panel: #ffffff;
  --text: #1a1a1a;
  --text-secondary: #333333;
  --text-accent: #4a90e2;
  --muted: #666666;
  --button: #e8e8e8;
  --button-hover: #d0d0d0;
  --border: #cccccc;
  --canvas: #fafafa;
  --grid: rgba(0, 0, 0, 0.12);
  --grid-dark: rgba(0, 0, 0, 0.25);
  --shadow: rgba(0, 0, 0, 0.1);
  --modal-bg: #ffffff;
  --modal-border: #d0d0d0;
}

/* ================= BASE STYLES ================= */

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  font-family: Inter, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  background: linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bottom) 100%);
  color: var(--text);
  transition: background 0.3s ease, color 0.3s ease;
}

.wrap {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  gap: 24px;
  padding: 24px;
  box-sizing: border-box;
}

.game {
  display: flex;
  gap: 18px;
}

/* ================= CANVAS ================= */

canvas {
  background: var(--canvas);
  image-rendering: pixelated;
  border-radius: 8px;
  box-shadow: 0 8px 30px var(--shadow);
  transition: background 0.3s ease, box-shadow 0.3s ease;
  display: block;
}

/* ================= UI PANEL ================= */

.ui {
  width: 220px;
  padding: 18px;
  border-radius: 10px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.02), rgba(255, 255, 255, 0.01));
  box-shadow: 0 6px 20px var(--shadow);
  transition: background 0.3s ease, box-shadow 0.3s ease, color 0.3s ease;
}

body.light .ui {
  background: linear-gradient(180deg, rgba(0, 0, 0, 0.02), rgba(0, 0, 0, 0.01));
}

.ui h1 {
  font-size: 18px;
  margin: 0 0 10px;
  color: var(--text-secondary);
  transition: color 0.3s ease;
}

.stat {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
  color: var(--muted);
  transition: color 0.3s ease;
}

.stat strong {
  color: var(--text);
  transition: color 0.3s ease;
}

.small {
  font-size: 12px;
  color: var(--text-accent);
  transition: color 0.3s ease;
}

.controls {
  font-size: 13px;
  margin-top: 12px;
  color: var(--muted);
  transition: color 0.3s ease;
  line-height: 1.6;
}

/* ================= BUTTONS ================= */

button {
  width: 100%;
  padding: 10px 12px;
  margin-top: 12px;
  border-radius: 8px;
  border: none;
  background: var(--button);
  color: var(--text);
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 500;
  font-size: 14px;
}

button:hover:not(:disabled) {
  background: var(--button-hover);
}

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

button:not(:disabled):active {
  transform: scale(0.98);
}

/* ================= THEME TOGGLE BUTTON ================= */

#themeToggle {
  position: fixed;
  top: 12px;
  right: 12px;
  width: 44px;
  height: 44px;
  padding: 0;
  border-radius: 50%;
  border: 2px solid var(--accent-primary);
  background: var(--button);
  color: var(--text);
  font-size: 24px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  z-index: 100;
}

#themeToggle:hover {
  box-shadow: 0 0 15px var(--accent-primary);
  transform: scale(1.1);
}

#themeToggle:active {
  transform: scale(0.98);
}

/* ================= DIFFICULTY MENU ================= */

.difficulty-menu {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  transition: background 0.3s ease;
}

body.light .difficulty-menu {
  background: rgba(0, 0, 0, 0.7);
}

.difficulty-container {
  text-align: center;
  background: var(--modal-bg);
  padding: 40px;
  border-radius: 16px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.8);
  border: 2px solid var(--modal-border);
  transition: all 0.3s ease;
}

.difficulty-container h2 {
  font-size: 32px;
  margin: 0 0 30px;
  color: var(--text-secondary);
  transition: color 0.3s ease;
}

.difficulty-btn {
  width: 180px;
  padding: 16px 20px;
  font-size: 18px;
  margin: 10px auto;
  border: 2px solid var(--accent-primary);
  background: var(--button);
  color: var(--text);
  cursor: pointer;
  border-radius: 10px;
  transition: all 0.3s ease;
  font-weight: bold;
  display: inline-block;
}

.difficulty-btn:hover {
  background: var(--button-hover);
  box-shadow: 0 0 15px var(--accent-primary);
}

/* ================= GAME OVER OVERLAY ================= */

.game-over-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.8);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  backdrop-filter: blur(2px);
  transition: background 0.3s ease;
}

body.light .game-over-overlay {
  background: rgba(0, 0, 0, 0.7);
}

.game-over-overlay.active {
  display: flex;
}

.game-over-content {
  text-align: center;
  background: var(--modal-bg);
  padding: 60px 40px;
  border-radius: 16px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.9);
  border: 2px solid var(--modal-border);
  animation: slideIn 0.4s ease-out;
  transition: all 0.3s ease;
}

.game-over-content h2 {
  font-size: 48px;
  margin: 0 0 20px;
  color: var(--accent-error);
  font-weight: bold;
}

.game-over-content p {
  font-size: 18px;
  color: var(--text);
  margin: 10px 0;
  letter-spacing: 0.5px;
  transition: color 0.3s ease;
}

.game-over-button {
  padding: 16px 32px;
  font-size: 18px;
  margin: 20px auto;
  border: 2px solid var(--accent-primary);
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-success));
  color: #fff;
  cursor: pointer;
  border-radius: 10px;
  transition: all 0.3s ease;
  font-weight: bold;
  display: inline-block;
  width: auto;
}

.game-over-button:hover {
  box-shadow: 0 0 30px rgba(77, 150, 255, 0.8);
  transform: scale(1.05);
}

.game-over-button:active {
  transform: scale(0.98);
}

/* ================= NEXT PIECE PREVIEW ================= */

.next-preview-panel {
  width: 120px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.next-preview {
  padding: 12px;
  background: var(--modal-bg);
  border-radius: 8px;
  border: 1px solid var(--border);
  transition: all 0.3s ease;
}

.next-preview h3 {
  margin: 0 0 8px;
  font-size: 12px;
  color: var(--text-accent);
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: color 0.3s ease;
}

.next-preview-canvas {
  width: 100%;
  height: 100px;
  background: var(--canvas);
  border-radius: 4px;
  display: block;
  transition: background 0.3s ease;
  image-rendering: pixelated;
}

/* ================= UI STATE CHANGES ================= */

.ui.game-over {
  opacity: 0.45;
  filter: blur(1px);
  pointer-events: none;
}

.ui.game-over button {
  opacity: 0.4;
  pointer-events: none;
}

#btnRestart {
  pointer-events: auto;
  z-index: 100;
}

#btnRestart.active {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-success));
  color: #fff;
  font-weight: bold;
  animation: pulse 1.5s ease-in-out infinite;
  box-shadow: 0 0 20px rgba(77, 150, 255, 0.6);
}

#btnRestart.active:hover {
  box-shadow: 0 0 30px rgba(77, 150, 255, 1);
  transform: scale(1.05);
}

/* ================= FOOTER ================= */

footer {
  position: fixed;
  bottom: 12px;
  left: 12px;
  color: var(--muted);
  font-size: 12px;
  transition: color 0.3s ease;
}

/* ================= ANIMATIONS ================= */

@keyframes slideIn {
  from {
    transform: translateY(-50px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 15px rgba(77, 150, 255, 0.5);
  }
  50% {
    box-shadow: 0 0 30px rgba(77, 150, 255, 0.8);
  }
  100% {
    box-shadow: 0 0 15px rgba(77, 150, 255, 0.5);
  }
}