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

html {
  overflow: hidden;
  height: 100%;
}

body {
  background: #16213e;
  background: radial-gradient(ellipse at top, #1a1a2e 0%, #16213e 100%);
  height: 100%;
  overflow: hidden;
  font-family: "Nunito", "Clear Sans", Arial, sans-serif;
  color: #f0e6d3;
  display: flex;
  justify-content: center;
  padding: max(20px, env(safe-area-inset-top))
           max(16px, env(safe-area-inset-right))
           max(20px, env(safe-area-inset-bottom))
           max(16px, env(safe-area-inset-left));
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.container {
  width: 500px;
  max-width: 100%;
}

/* ── Header ───────────────────────────────────────────────────────── */

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
}

h1 {
  font-size: clamp(48px, 14vw, 76px);
  font-weight: 900;
  line-height: 1;
  background: linear-gradient(135deg, #f67c5f 0%, #edc22e 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  filter: drop-shadow(0 4px 8px rgba(246,124,95,0.4));
}

.scores {
  display: flex;
  gap: 10px;
}

.score-box {
  position: relative;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 16px;
  padding: 10px 18px;
  text-align: center;
  min-width: 84px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.3), inset 0 1px 2px rgba(255,255,255,0.1);
  overflow: visible;
}

.score-label {
  display: block;
  font-size: 11px;
  font-weight: 800;
  color: rgba(255,255,255,0.5);
  letter-spacing: 1.5px;
}

.score-value {
  display: block;
  font-size: clamp(16px, 5vw, 24px);
  font-weight: 900;
  color: #fff;
}

.score-value.score-flash {
  animation: score-pop 0.35s ease-out;
}

@keyframes score-pop {
  0%   { transform: scale(1);    color: #fff; }
  45%  { transform: scale(1.22); color: #edc22e; }
  100% { transform: scale(1);    color: #fff; }
}

.score-delta {
  position: absolute;
  top: -4px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 13px;
  font-weight: 900;
  color: #edc22e;
  text-shadow: 0 2px 10px rgba(237,194,46,0.9);
  pointer-events: none;
  white-space: nowrap;
  z-index: 100;
}

/* ── Subheader ────────────────────────────────────────────────────── */

.subheader {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.subheader p {
  font-size: 15px;
  color: rgba(240,230,211,0.7);
}

#new-game-btn {
  background: linear-gradient(145deg, #f67c5f, #f65e3b);
  color: #fff;
  border: none;
  border-radius: 14px;
  padding: 10px 22px;
  min-height: 44px;
  font-size: 15px;
  font-weight: 800;
  font-family: inherit;
  cursor: pointer;
  box-shadow: 0 5px 0 #b83518, 0 8px 20px rgba(246,94,59,0.4), inset 0 1px 3px rgba(255,255,255,0.3);
  transition: transform 0.08s, box-shadow 0.08s;
}

#new-game-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 0 #b83518, 0 10px 24px rgba(246,94,59,0.45), inset 0 1px 3px rgba(255,255,255,0.3);
}

#new-game-btn:active {
  transform: translateY(4px);
  box-shadow: 0 1px 0 #b83518, 0 4px 12px rgba(246,94,59,0.3), inset 0 1px 3px rgba(255,255,255,0.2);
}

/* ── Grid ─────────────────────────────────────────────────────────── */

.grid-container {
  position: relative;
  background: #1e1e3a;
  border-radius: 20px;
  padding: 14px;
  aspect-ratio: 1;
  box-shadow:
    0 12px 0 #0d0d1e,
    0 20px 50px rgba(0,0,0,0.5),
    inset 0 1px 2px rgba(255,255,255,0.05);
}

.grid-background,
.grid-tiles {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  width: 100%;
  height: 100%;
}

.grid-background {
  position: absolute;
  inset: 14px;
}

.grid-tiles {
  position: absolute;
  inset: 14px;
}

.cell {
  background: rgba(255, 255, 255, 0.04);
  border-radius: 14px;
  border: 1px solid rgba(255,255,255,0.06);
}

/* ── Tiles (Claymorphism) ─────────────────────────────────────────── */

.tile {
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: inherit;
  font-weight: 900;
  font-size: clamp(24px, 7vw, 38px);
  background: transparent;
  color: transparent;
  will-change: transform;
}

/* Font scaling for large numbers */
.tile[data-value="128"],
.tile[data-value="256"],
.tile[data-value="512"] {
  font-size: 28px;
}

.tile[data-value="1024"],
.tile[data-value="2048"] {
  font-size: 21px;
}

/* ── Tile colors + clay shadows ───────────────────────────────────── */

.tile[data-value="2"] {
  background: linear-gradient(145deg, #f5ede3, #eee4da);
  color: #776e65;
  box-shadow: 0 6px 0 #c4b8a8, 0 10px 24px rgba(0,0,0,0.25), inset 0 2px 4px rgba(255,255,255,0.7);
}
.tile[data-value="4"] {
  background: linear-gradient(145deg, #f5e5ca, #ede0c8);
  color: #776e65;
  box-shadow: 0 6px 0 #c4b090, 0 10px 24px rgba(0,0,0,0.25), inset 0 2px 4px rgba(255,255,255,0.7);
}
.tile[data-value="8"] {
  background: linear-gradient(145deg, #f7c090, #f2b179);
  color: #fff;
  box-shadow: 0 6px 0 #c47d40, 0 10px 24px rgba(242,177,121,0.4), inset 0 2px 4px rgba(255,255,255,0.5);
}
.tile[data-value="16"] {
  background: linear-gradient(145deg, #f8a87a, #f59563);
  color: #fff;
  box-shadow: 0 6px 0 #c46030, 0 10px 24px rgba(245,149,99,0.45), inset 0 2px 4px rgba(255,255,255,0.4);
}
.tile[data-value="32"] {
  background: linear-gradient(145deg, #f89074, #f67c5f);
  color: #fff;
  box-shadow: 0 6px 0 #c04428, 0 10px 24px rgba(246,124,95,0.5), inset 0 2px 4px rgba(255,255,255,0.4);
}
.tile[data-value="64"] {
  background: linear-gradient(145deg, #f87558, #f65e3b);
  color: #fff;
  box-shadow: 0 6px 0 #bc2a10, 0 10px 24px rgba(246,94,59,0.55), inset 0 2px 4px rgba(255,255,255,0.35);
}
.tile[data-value="128"] {
  background: linear-gradient(145deg, #f2da88, #edcf72);
  color: #fff;
  box-shadow: 0 6px 0 #c4a030, 0 10px 24px rgba(237,207,114,0.5), inset 0 2px 4px rgba(255,255,255,0.5);
}
.tile[data-value="256"] {
  background: linear-gradient(145deg, #f2d778, #edcc61);
  color: #fff;
  box-shadow: 0 6px 0 #c49d25, 0 10px 24px rgba(237,204,97,0.5), inset 0 2px 4px rgba(255,255,255,0.5);
}
.tile[data-value="512"] {
  background: linear-gradient(145deg, #f2d368, #edc850);
  color: #fff;
  box-shadow: 0 6px 0 #c49a10, 0 10px 24px rgba(237,200,80,0.5), inset 0 2px 4px rgba(255,255,255,0.5);
}
.tile[data-value="1024"] {
  background: linear-gradient(145deg, #f2cf55, #edc53f);
  color: #fff;
  box-shadow: 0 6px 0 #c49700, 0 10px 24px rgba(237,197,63,0.55), inset 0 2px 4px rgba(255,255,255,0.5);
}
.tile[data-value="2048"] {
  background: linear-gradient(145deg, #f2cc44, #edc22e);
  color: #fff;
  box-shadow: 0 6px 0 #c49500, 0 10px 30px rgba(237,194,46,0.65), inset 0 2px 4px rgba(255,255,255,0.55);
  animation: glow-pulse 1.8s ease-in-out infinite;
}

@keyframes glow-pulse {
  0%, 100% { filter: drop-shadow(0 0 8px rgba(237,194,46,0.6)); }
  50%       { filter: drop-shadow(0 0 18px rgba(237,194,46,0.9)); }
}

/* ── Overlays (Glassmorphism) ─────────────────────────────────────── */

.overlay {
  display: none;
  position: absolute;
  inset: 0;
  border-radius: 20px;
  background: rgba(22, 33, 62, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border: 1px solid rgba(255,255,255,0.1);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
  z-index: 10;
}

.overlay.visible {
  display: flex;
}

.overlay p {
  font-size: clamp(32px, 10vw, 52px);
  font-weight: 900;
  color: #fff;
  text-shadow: 0 4px 20px rgba(0,0,0,0.4);
}

.overlay-actions {
  display: flex;
  gap: 14px;
}

.overlay-btn {
  background: linear-gradient(145deg, rgba(255,255,255,0.18), rgba(255,255,255,0.08));
  color: #fff;
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: 14px;
  padding: 12px 26px;
  min-height: 44px;
  font-size: 17px;
  font-weight: 800;
  font-family: inherit;
  cursor: pointer;
  backdrop-filter: blur(8px);
  box-shadow: 0 4px 0 rgba(0,0,0,0.3), 0 8px 20px rgba(0,0,0,0.2), inset 0 1px 2px rgba(255,255,255,0.2);
  transition: transform 0.08s, box-shadow 0.08s;
}

.overlay-btn:hover {
  transform: translateY(-1px);
  background: linear-gradient(145deg, rgba(255,255,255,0.24), rgba(255,255,255,0.12));
}

.overlay-btn:active {
  transform: translateY(3px);
  box-shadow: 0 1px 0 rgba(0,0,0,0.3), 0 4px 10px rgba(0,0,0,0.2), inset 0 1px 2px rgba(255,255,255,0.1);
}

/* ── Instructions ─────────────────────────────────────────────────── */

.instructions {
  margin-top: 18px;
  font-size: 13px;
  text-align: center;
  color: rgba(240,230,211,0.45);
  font-weight: 700;
}

/* ── TV / large screen (PS5 browser: 1920×1080) ──────────────────── */

@media (min-width: 1200px) {
  body {
    padding: 60px 96px;
    align-items: center;
  }
  .container {
    width: min(680px, 80vh);
  }
}

/* ── Small screen (iPhone SE, 375px) ─────────────────────────────── */

@media (max-width: 400px) {
  .header { margin-bottom: 8px; }
  .subheader { margin-bottom: 12px; }
  .grid-container { padding: 10px; }
  .grid-background, .grid-tiles { gap: 10px; }
  .grid-background { inset: 10px; }
  .grid-tiles { inset: 10px; }
}