:root {
  --size: 4;
  --cell: 90px;
  --gap: 17px;
  --board: calc(var(--size) * var(--cell) + (var(--size) - 1) * var(--gap));
  --bg: #bbada0;
  --empty: #cdc1b4;
  --tile-2: #eee4da;
  --tile-4: #ede0c8;
  --tile-8: #f2b179;
  --tile-16: #f59563;
  --tile-32: #f67c5f;
  --tile-64: #f65e3b;
  --tile-128: #edcf72;
  --tile-256: #edcc61;
  --tile-512: #edc850;
  --tile-1024: #edc53f;
  --tile-2048: #edc22e;
}
* {
  box-sizing: border-box;
}
html,
body {
  display: grid;
  place-items: center;
  background: #faf8ef;
  color: #776e65;
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  height: 100%;
  overflow: hidden;
  overscroll-behavior-y: none;
}
.container {
  display: grid;
  gap: 12px;
}
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.title {
  font-size: 40px;
  font-weight: 800;
  letter-spacing: 1px;
}
.controls {
  display: flex;
  align-items: center;
  gap: 8px;
}
.score {
  background: #bbada0;
  color: white;
  padding: 6px 10px;
  border-radius: 6px;
  min-width: 64px;
  text-align: center;
  font-weight: 700;
}
.btn {
  appearance: none;
  border: 0;
  background: #8f7a66;
  color: white;
  padding: 8px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 700;
}
.btn:active {
  transform: translateY(1px);
}
.hint {
  text-align: center;
  opacity: 0.6;
  font-size: 12px;
}
.board {
  position: relative;
  width: var(--board);
  height: var(--board);
  background: var(--bg);
  border-radius: 8px;
  padding: var(--gap);
  overflow: hidden;
}

.tile {
  position: absolute;
  left: 0;
  top: 0;
  width: var(--cell);
  height: var(--cell);
  border-radius: 6px;
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 32px;
  color: #776e65;
  transition: transform 120ms ease, left 120ms ease, top 120ms ease, background 120ms ease,
    color 120ms ease;
  will-change: transform, left, top;
}

.tile.moving {
  transition: transform 120ms ease, background 120ms ease, color 120ms ease;
}
.tile.big {
  font-size: 28px;
}
.tile.bigger {
  font-size: 24px;
}
.tile.huge {
  font-size: 20px;
}
.tile.new {
  animation: pop-in 140ms ease;
}
.tile.bump {
  animation: bump 140ms ease;
}
@keyframes pop-in {
  from {
    transform: scale(0.6);
  }
  to {
    transform: scale(1);
  }
}
@keyframes bump {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.08);
  }
  100% {
    transform: scale(1);
  }
}
/* Colors */
.v2 {
  background: var(--tile-2);
}
.v4 {
  background: var(--tile-4);
}
.v8 {
  background: var(--tile-8);
  color: #f9f6f2;
}
.v16 {
  background: var(--tile-16);
  color: #f9f6f2;
}
.v32 {
  background: var(--tile-32);
  color: #f9f6f2;
}
.v64 {
  background: var(--tile-64);
  color: #f9f6f2;
}
.v128 {
  background: var(--tile-128);
  color: #f9f6f2;
}
.v256 {
  background: var(--tile-256);
  color: #f9f6f2;
}
.v512 {
  background: var(--tile-512);
  color: #f9f6f2;
}
.v1024 {
  background: var(--tile-1024);
  color: #f9f6f2;
}
.v2048 {
  background: var(--tile-2048);
  color: #f9f6f2;
}