.container {
  position: relative;
  transition: width 450ms cubic-bezier(0.22, 1, 0.36, 1);
}

.game-container {
  box-sizing: border-box;
  border-radius: 6px;
  transition: width 450ms cubic-bezier(0.22, 1, 0.36, 1),
              height 450ms cubic-bezier(0.22, 1, 0.36, 1),
              padding 450ms cubic-bezier(0.22, 1, 0.36, 1),
              box-shadow 450ms ease;
  overflow: visible;
}

.game-container.is-board-growing {
  overflow: hidden;
}

.game-container .grid-container {
  position: absolute;
  z-index: 1;
  left: var(--grid-spacing, 15px);
  top: var(--grid-spacing, 15px);
  right: var(--grid-spacing, 15px);
  bottom: var(--grid-spacing, 15px);
  display: grid;
  grid-template-columns: repeat(var(--board-cells, 4), 1fr);
  grid-template-rows: repeat(var(--board-cells, 4), 1fr);
  gap: var(--grid-spacing, 15px);
  box-sizing: border-box;
}

/* Kill original float-row clearfix artifacts */
.game-container .grid-row {
  display: contents;
}

.game-container .grid-row:after {
  content: none !important;
  display: none !important;
}

.game-container .grid-cell {
  width: auto;
  height: auto;
  margin: 0 !important;
  float: none !important;
  border-radius: 6px;
  min-width: 0;
  min-height: 0;
  background: var(--cell-bg);
  box-shadow: var(--cell-shadow);
  transition: opacity 420ms ease, transform 420ms ease;
}

.game-container .tile-container {
  left: var(--grid-spacing, 15px);
  top: var(--grid-spacing, 15px);
}

.game-container .tile,
.game-container .tile .tile-inner {
  width: var(--tile-size, 106.25px);
  height: var(--tile-size, 106.25px);
  line-height: var(--tile-size, 106.25px);
  font-size: var(--tile-font-size, 55px);
  box-sizing: border-box;
  border-radius: 6px;
}

.game-container.is-board-growing .tile {
  transition: transform 450ms cubic-bezier(0.22, 1, 0.36, 1),
              width 450ms cubic-bezier(0.22, 1, 0.36, 1),
              height 450ms cubic-bezier(0.22, 1, 0.36, 1);
}

.game-container.is-board-growing .tile .tile-inner {
  transition: width 450ms cubic-bezier(0.22, 1, 0.36, 1),
              height 450ms cubic-bezier(0.22, 1, 0.36, 1),
              line-height 450ms cubic-bezier(0.22, 1, 0.36, 1),
              font-size 450ms cubic-bezier(0.22, 1, 0.36, 1);
}

.game-container .tile.tile-128 .tile-inner,
.game-container .tile.tile-256 .tile-inner,
.game-container .tile.tile-512 .tile-inner {
  font-size: var(--tile-font-size-mid, 45px);
}

.game-container .tile.tile-1024 .tile-inner,
.game-container .tile.tile-2048 .tile-inner {
  font-size: var(--tile-font-size-large, 35px);
}

.game-container .tile.tile-super .tile-inner {
  font-size: var(--tile-font-size-super, 30px);
}

.grid-cell.is-new {
  opacity: 0;
  transform: scale(0.7);
}

.game-container.is-board-growing .grid-cell.is-new,
.game-container.is-board-ready .grid-cell.is-new {
  opacity: 1;
  transform: scale(1);
}

/* Expansion celebration overlay */
.expand-overlay {
  position: fixed;
  inset: 0;
  z-index: 4000;
  pointer-events: none;
  overflow: hidden;
}

.expand-sparkle {
  position: absolute;
  left: var(--x);
  top: var(--y);
  width: var(--size);
  height: var(--size);
  margin-left: calc(var(--size) / -2);
  margin-top: calc(var(--size) / -2);
  border-radius: 50%;
  background: var(--color);
  box-shadow: 0 0 12px var(--color);
  opacity: 0;
  animation: expand-sparkle-burst 1100ms ease-out forwards;
  animation-delay: var(--delay);
}

.expand-sparkle.is-star {
  border-radius: 2px;
  clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}

.expand-flash {
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255, 255, 255, 0.55), transparent 55%);
  animation: expand-flash 900ms ease-out forwards;
}

@keyframes expand-sparkle-burst {
  0% {
    opacity: 0;
    transform: translate(0, 0) scale(0.2);
  }
  20% {
    opacity: 1;
    transform: translate(calc(var(--dx) * 0.2), calc(var(--dy) * 0.2)) scale(1.3);
  }
  100% {
    opacity: 0;
    transform: translate(var(--dx), var(--dy)) scale(0.2);
  }
}

@keyframes expand-flash {
  0% { opacity: 0; }
  25% { opacity: 1; }
  100% { opacity: 0; }
}

@keyframes expand-earthquake {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  10% { transform: translate(-5px, 2px) rotate(-0.35deg); }
  20% { transform: translate(6px, -3px) rotate(0.4deg); }
  30% { transform: translate(-4px, -2px) rotate(-0.25deg); }
  40% { transform: translate(5px, 2px) rotate(0.3deg); }
  50% { transform: translate(-3px, 3px) rotate(-0.35deg); }
  60% { transform: translate(4px, -2px) rotate(0.25deg); }
  70% { transform: translate(-2px, -3px) rotate(-0.15deg); }
  80% { transform: translate(2px, 2px) rotate(0.15deg); }
  90% { transform: translate(-1px, 1px) rotate(-0.08deg); }
}

body.is-expanding .container {
  animation: expand-earthquake 1100ms linear;
}

body.is-expanding .game-container {
  box-shadow: 0 18px 50px rgba(0, 0, 0, 0.22);
}

@media (prefers-reduced-motion: reduce) {
  .container,
  .game-container,
  .game-container .grid-cell,
  .game-container.is-board-growing .tile,
  .game-container.is-board-growing .tile .tile-inner {
    transition: none !important;
  }

  body.is-expanding .container,
  .expand-sparkle,
  .expand-flash {
    animation: none !important;
  }
}

@media screen and (max-width: 520px) {
  body {
    padding-left: 12px;
    padding-right: 12px;
  }
}