/**
 * Browser Arcade - 2048 Game Styling & Animations
 * Hardware-accelerated 60 FPS transitions and responsive grid layout.
 */

:root {
  --grid-size: min(92vw, 460px);
  --grid-gap: clamp(8px, 2.2vw, 14px);
  --cell-size: calc((var(--grid-size) - (var(--grid-gap) * 5)) / 4);
}

/* ==========================================================================
   Game Page Header & HUD
   ========================================================================== */

.game-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: var(--grid-size);
  margin: 0 auto;
  padding: 16px 0 32px;
}

.game-hud {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  margin-bottom: 16px;
  gap: 12px;
}

.game-title-group {
  display: flex;
  flex-direction: column;
}

.game-title {
  font-size: clamp(2rem, 6vw, 3rem);
  font-weight: 900;
  letter-spacing: -0.04em;
  line-height: 1;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.game-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
  margin-top: 4px;
}

.game-scores {
  display: flex;
  align-items: center;
  gap: 8px;
}

.score-box {
  position: relative;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 8px 14px;
  min-width: 80px;
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.score-box-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.score-box-value {
  font-size: clamp(1.1rem, 3.5vw, 1.45rem);
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.2;
}

/* Score floating increment animation */
.score-addition {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1rem;
  font-weight: 800;
  color: var(--accent-emerald);
  pointer-events: none;
  opacity: 0;
  animation: score-float 600ms ease-out forwards;
}

@keyframes score-float {
  0% {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
  }
  100% {
    opacity: 0;
    transform: translate(-50%, -180%) scale(1.2);
  }
}

/* ==========================================================================
   Game Controls Toolbar
   ========================================================================== */

.game-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  margin-bottom: 16px;
  gap: 10px;
}

.game-toolbar-left,
.game-toolbar-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ==========================================================================
   4x4 Game Board
   ========================================================================== */

.game-board-container {
  position: relative;
  width: var(--grid-size);
  height: var(--grid-size);
  background: var(--bg-board);
  border: 2px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--grid-gap);
  touch-action: none; /* Prevents mobile scroll while swiping */
  user-select: none;
  -webkit-user-select: none;
  box-shadow: var(--shadow-lg), inset 0 2px 6px rgba(0, 0, 0, 0.4);
}

.grid-background {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);
  gap: var(--grid-gap);
  width: 100%;
  height: 100%;
}

.grid-cell {
  background: var(--bg-cell-empty);
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.02);
}

/* ==========================================================================
   Tile Styling & Hardware-Accelerated Animations
   ========================================================================== */

.tile-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.tile {
  position: absolute;
  width: var(--cell-size);
  height: var(--cell-size);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  letter-spacing: -0.02em;
  user-select: none;
  will-change: transform;
  /* Hardware accelerated transform with GPU rasterization */
  transform: translate3d(
    calc(var(--col) * (var(--cell-size) + var(--grid-gap)) + var(--grid-gap)),
    calc(var(--row) * (var(--cell-size) + var(--grid-gap)) + var(--grid-gap)),
    0
  );
  transition: transform 115ms cubic-bezier(0.25, 1, 0.5, 1);
}

.tile-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  border-radius: var(--radius-md);
  font-size: clamp(1.6rem, 5vw, 2.2rem);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.25);
}

/* Font size adjustments for larger digit counts */
.tile[data-digits="3"] .tile-inner {
  font-size: clamp(1.25rem, 4vw, 1.7rem);
}

.tile[data-digits="4"] .tile-inner {
  font-size: clamp(1rem, 3.2vw, 1.35rem);
}

.tile[data-digits="5"] .tile-inner {
  font-size: clamp(0.85rem, 2.6vw, 1.1rem);
}

/* New tile spawn animation */
.tile-new .tile-inner {
  animation: tile-spawn 140ms ease-out forwards;
}

@keyframes tile-spawn {
  0% {
    opacity: 0;
    transform: scale(0);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}

/* Merged tile pop animation */
.tile-merged {
  z-index: 10;
}

.tile-merged .tile-inner {
  animation: tile-pop 160ms cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

@keyframes tile-pop {
  0% {
    transform: scale(0.9);
  }
  50% {
    transform: scale(1.18);
  }
  100% {
    transform: scale(1);
  }
}

/* ==========================================================================
   Tile Color System
   ========================================================================== */

.tile-2 .tile-inner {
  background: var(--tile-2-bg);
  color: var(--tile-2-color);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.tile-4 .tile-inner {
  background: var(--tile-4-bg);
  color: var(--tile-4-color);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.tile-8 .tile-inner {
  background: var(--tile-8-bg);
  color: var(--tile-8-color);
}

.tile-16 .tile-inner {
  background: var(--tile-16-bg);
  color: var(--tile-16-color);
}

.tile-32 .tile-inner {
  background: var(--tile-32-bg);
  color: var(--tile-32-color);
}

.tile-64 .tile-inner {
  background: var(--tile-64-bg);
  color: var(--tile-64-color);
}

.tile-128 .tile-inner {
  background: var(--tile-128-bg);
  color: var(--tile-128-color);
  box-shadow: var(--tile-128-glow);
}

.tile-256 .tile-inner {
  background: var(--tile-256-bg);
  color: var(--tile-256-color);
  box-shadow: var(--tile-256-glow);
}

.tile-512 .tile-inner {
  background: var(--tile-512-bg);
  color: var(--tile-512-color);
  box-shadow: var(--tile-512-glow);
}

.tile-1024 .tile-inner {
  background: var(--tile-1024-bg);
  color: var(--tile-1024-color);
  box-shadow: var(--tile-1024-glow);
}

.tile-2048 .tile-inner {
  background: var(--tile-2048-bg);
  color: var(--tile-2048-color);
  box-shadow: var(--tile-2048-glow);
}

.tile-super .tile-inner {
  background: var(--tile-super-bg);
  color: var(--tile-super-color);
  box-shadow: var(--tile-super-glow);
}

/* ==========================================================================
   Overlay Modals (Game Over & Victory)
   ========================================================================== */

.game-overlay {
  position: absolute;
  inset: 0;
  background: rgba(14, 16, 26, 0.88);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px;
  z-index: 50;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

.game-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.game-overlay-title {
  font-size: clamp(1.8rem, 5vw, 2.4rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.game-overlay-desc {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  text-align: center;
}

.game-overlay-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

/* ==========================================================================
   Instructions & Guide Section
   ========================================================================== */

.game-info-card {
  width: 100%;
  margin-top: 24px;
  padding: 20px;
  background: var(--bg-surface-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
}

.game-info-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.game-info-text {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.controls-badge-grid {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  flex-wrap: wrap;
}

.control-key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 28px;
  height: 28px;
  padding: 0 8px;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-main);
  box-shadow: 0 2px 0 rgba(0, 0, 0, 0.4);
}

/* ==========================================================================
   Reduced Motion Accessibility Preference
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  .tile {
    transition: none !important;
  }
  .tile-new .tile-inner,
  .tile-merged .tile-inner,
  .score-addition {
    animation: none !important;
  }
}