:root {
  --tile-0: rgba(249, 252, 252, 0.62);
  --tile-2: #e0edef;
  --tile-4: #d3e5e8;
  --tile-8: #b8d6dc;
  --tile-16: #93bec9;
  --tile-32: #6d9eb0;
  --tile-64: #477c91;
  --tile-128: #315d72;
  --tile-strong: #17303d;
}
.game-shell {
  max-width: 1020px;
  margin: auto;
  padding: 58px 42px 82px;
}
.game-intro {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 32px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--line);
}
.game-intro h1 {
  margin: 0;
  font: 600 clamp(3.2rem, 8vw, 6rem)/0.95 var(--serif);
  letter-spacing: -0.06em;
}
.game-intro p:not(.eyebrow) {
  margin: 17px 0 0;
  color: var(--muted);
  font-size: 15px;
}
.record-card,
.score-card {
  min-width: 142px;
  padding: 12px 15px;
  border: 1px solid var(--line);
  background: var(--surface);
  text-align: right;
}
.record-card span,
.score-card span {
  display: block;
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.11em;
}
.record-card b,
.score-card b {
  display: block;
  margin: 1px 0;
  color: var(--ink);
  font: 600 1.85rem/1.2 var(--serif);
}
.record-card small {
  display: block;
  min-height: 1.5em;
  color: var(--accent);
  font-size: 12px;
}
.game-layout {
  display: grid;
  grid-template-columns: minmax(0, 540px) 1fr;
  gap: 50px;
  align-items: start;
  padding-top: 38px;
}
.game-panel {
  min-width: 0;
}
.game-toolbar {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  margin-bottom: 15px;
}
.score-card {
  min-width: 120px;
  text-align: left;
}
.score-card b {
  font-size: 1.55rem;
}
button {
  cursor: pointer;
  border: 1px solid var(--accent);
  padding: 10px 16px;
  background: var(--accent);
  color: var(--on-accent);
  font: 600 13px var(--sans);
  letter-spacing: 0.04em;
}
button:hover {
  background: var(--accent);
}
button:focus-visible,
.board:focus-visible,
input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}
.ghost {
  background: transparent;
  color: var(--accent);
  border-color: var(--line);
}
.ghost:hover {
  background: var(--panel);
  color: var(--ink);
}
.board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 10px;
  aspect-ratio: 1;
  border: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 42%, transparent);
  touch-action: none;
}
.tile {
  display: grid;
  place-items: center;
  min-width: 0;
  border: 1px solid color-mix(in srgb, var(--accent) 12%, transparent);
  background: var(--tile-0);
  color: var(--ink);
  font: 600 clamp(1.65rem, 6.1vw, 3.3rem)/1 var(--serif);
  transition:
    background 0.12s ease,
    transform 0.12s ease;
}
.tile[data-value='2'] {
  background: var(--tile-2);
}
.tile[data-value='4'] {
  background: var(--tile-4);
}
.tile[data-value='8'] {
  background: var(--tile-8);
}
.tile[data-value='16'] {
  background: var(--tile-16);
}
.tile[data-value='32'] {
  background: var(--tile-32);
  color: var(--on-accent);
}
.tile[data-value='64'] {
  background: var(--tile-64);
  color: var(--on-accent);
}
.tile[data-value='128'],
.tile[data-value='256'] {
  background: var(--tile-128);
  color: var(--on-accent);
}
.tile[data-value='512'],
.tile[data-value='1024'],
.tile[data-value='2048'] {
  background: var(--tile-strong);
  color: var(--on-accent);
}
.tile[data-value='1024'],
.tile[data-value='2048'] {
  font-size: clamp(1.2rem, 4.5vw, 2.5rem);
}
.game-message {
  min-height: 1.7em;
  margin: 13px 0 0;
  color: var(--accent);
  font-size: 13px;
}
.game-notes {
  padding: 24px;
  border-left: 2px solid var(--line);
  color: var(--muted);
  font-size: 14px;
  line-height: 1.8;
}
.game-notes p {
  margin: 0 0 16px;
}
.record-dialog {
  width: min(420px, calc(100% - 36px));
  padding: 0;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 16px 42px color-mix(in srgb, var(--ink) 18%, transparent);
}
.record-dialog::backdrop {
  background: color-mix(in srgb, var(--ink) 35%, transparent);
}
.record-dialog form {
  padding: 29px;
}
.record-dialog h2 {
  margin: 0;
  font: 600 2rem/1.2 var(--serif);
}
.record-dialog p:not(.eyebrow):not(.record-error) {
  color: var(--muted);
  font-size: 14px;
}
.record-dialog label {
  display: block;
  margin-top: 21px;
  color: var(--muted);
  font-size: 13px;
}
.record-dialog input {
  display: block;
  width: 100%;
  margin-top: 6px;
  padding: 10px 11px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  font: 16px var(--sans);
}
.record-error {
  min-height: 1.4em;
  margin: 8px 0 0;
  color: var(--danger);
  font-size: 12px;
}
.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 9px;
  margin-top: 16px;
}
@media (max-width: 800px) {
  .game-shell {
    padding: 38px 20px 60px;
  }
  .game-intro {
    align-items: start;
    flex-direction: column;
    gap: 20px;
  }
  .record-card {
    text-align: left;
  }
  .game-layout {
    grid-template-columns: 1fr;
    gap: 28px;
    padding-top: 28px;
  }
  .board {
    gap: 7px;
    padding: 7px;
  }
  .game-notes {
    padding: 18px;
  }
  .record-dialog form {
    padding: 24px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .tile {
    transition: none;
  }
}
:root {
  --game-over-paper: rgba(237, 243, 243, 0.88);
}
.board-wrap {
  position: relative;
}
.game-over {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 20px;
  background: var(--game-over-paper);
}
.game-over[hidden] {
  display: none;
}
.game-over-card {
  width: min(100%, 320px);
  padding: 28px 24px;
  border: 1px solid var(--line);
  background: var(--surface);
  text-align: center;
}
.game-over-card h2 {
  margin: 0;
  font: 600 clamp(1.6rem, 5vw, 2rem)/1.3 var(--serif);
}
.game-over-card p {
  margin: 12px 0;
  color: var(--muted);
  font-size: 14px;
}
.game-over-card .game-over-score {
  margin: 20px 0;
}
.game-over-score b {
  display: block;
  margin-top: 5px;
  color: var(--ink);
  font: 600 2rem/1.2 var(--serif);
}
.game-over-card button {
  min-height: 44px;
}