:root {
  --bg: #f6f4ef;
  --ink: #202124;
  --grid: #9aa0a6;
  --fixed: #d5ecff;
  --accepted: #89e59c;
  --page-max-width: 1120px;
  --page-padding: 20px;
  --page-padding-small: 12px;
  --layout-gap: 18px;
  --board-header-gap: 10px;
  --control-radius: 6px;
  --control-gap: 8px;
  --grid-size: 8; /* overridden by GRID_SIZE */
  --board-max-size: calc(var(--page-max-width) / 2);
  --board-min-cell-size: 36px;
  --board-gap: 2px;
  --board-padding: 6px;
  --board-border-width: 2px;
  --board-border-color: #5f6368;
  --board-min-size: calc(
    (var(--grid-size, 8) * var(--board-min-cell-size)) +
    ((var(--grid-size, 8) - 1) * var(--board-gap)) +
    (2 * var(--board-padding)) +
    (2 * var(--board-border-width))
  );
  --board-track-min: min(var(--board-min-size), var(--board-max-size));
  --rack-size: 7;
  --rack-min-tile-size: 34px;
  --rack-gap: 8px;
  --side-min-width: calc(
    (var(--rack-size) * var(--rack-min-tile-size)) +
    ((var(--rack-size) - 1) * var(--rack-gap))
  );
  --cell-font-min: 18px;
  --cell-font-max: 42px;
  --cell-font-scale: 46cqi;
  --rack-font-min: 18px;
  --rack-font-max: 36px;
  --rack-font-scale: 42cqi;
  --rack-tile-texture: repeating-linear-gradient(45deg, rgba(0, 0, 0, 0.03) 0, rgba(0, 0, 0, 0.1) 3px, transparent 2px, transparent 6px);
  --rack-tile-background: var(--rack-tile-texture) #f5cf90;
  --rack-tile-border: 2px solid #8a6d00;
  --rack-tile-border-radius: var(--control-radius);
  --rack-tile-color: var(--ink);
  --rack-tile-box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.6), inset 0 -1px 0 rgba(0, 0, 0, 0.1);
  --rack-tile-active: var(--rack-tile-texture) #ffe59a;
  --score-value-size: 56px;
  --high-score-value-size: 20px;
  --scoreboard-row-gap: 0;
  --scoreboard-padding-block: 0;
  --scoreboard-padding-inline: 0;
  --language-trigger-size: 44px;
  --language-flag-size: 22px;
  --language-screen-gap: 18px;
  --language-option-padding: 16px;
  --score-bounce-scale: 1.7;
  --score-bounce-rise-duration: 50ms;
  --score-bounce-settle-duration: 500ms;
  --celebration-label-duration: 1200ms; /* overridden by CELEBRATION_LABEL_DURATION_MS */
  --celebration-points-duration: 300ms; /* overridden by CELEBRATION_POINTS_DURATION_MS */
  --celebration-points-delay: 240ms; /* overridden by CELEBRATION_POINTS_DELAY_MS */
  --celebration-label-size: 12cqi;
  --celebration-label-color: #6399ff;
  --celebration-points-size: 16cqi;
  --celebration-points-color: #aa5aff;
  --celebration-points-entry-scale: 4;
  --celebration-outline-width: clamp(2px, 0.8cqi, 8px);
  --celebration-outline-color: #ffffff;
  --celebration-text-shadow: 0 0.06em 0.1em rgb(0 0 0 / 0.55);
  --celebration-gap: 12px;
  --game-over-duration: 500ms; /* overridden by GAME_OVER_ANIMATION_DURATION_MS */
  --game-over-entry-scale: 0.7;
  --game-over-overshoot-scale: 1.08;
  --game-over-label-color-1: #5c0a0a;
  --game-over-label-color-2: #bf9a00;
  --game-over-label-color-3: #002e60;
  --game-over-label-color-4: #320000;
  --game-over-color-duration: 7000ms;
  --play-again-width: 46cqi;
  --play-again-height: 14cqi;
  --play-again-background: #20c900;
  --play-again-border: 2px solid #159000;
  --play-again-border-radius: 3cqi;
  --play-again-icon-size: 9cqi;
  --play-again-box-shadow: 0 0.8cqi 1.5cqi rgb(0 0 0 / 0.35), inset 0 0.5cqi 0.8cqi rgb(255 255 255 / 0.35);
  --round-tile-background: var(--rack-tile-background);
  --round-tile-border: var(--rack-tile-border);
  --round-tile-border-radius: var(--control-radius);
  --round-tile-box-shadow: var(--rack-tile-box-shadow);
  --round-tile-color: transparent;
  --rejected-tile-shake-distance: 2%;
  --rejected-tile-shake-rotation: 2deg;
  --rejected-tile-shake-duration: 420ms;
  --rejected-tile-dim: 0.96;
  --drag-target-color: #d5ecff;
  --drag-source-background: linear-gradient(rgb(255 255 255 / 70%), rgb(255 255 255 / 70%)), var(--rack-tile-texture) #f5cf90;
  --drag-source-border-color: #dccfaa;
  --drag-source-color: #bcbcbc;
  --rack-insertion-width: 4px;
  --rack-insertion-offset: -8px;
}

html {
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  -ms-text-size-adjust: 100%;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

html,
body {
  touch-action: pan-y;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.35;
}

main {
  max-width: var(--page-max-width);
  margin: 0 auto;
  padding: var(--page-padding);
}

.layout {
  display: grid;
  grid-template-columns: minmax(var(--board-track-min), var(--board-max-size)) minmax(var(--side-min-width), 1fr);
  grid-template-areas:
    "scoreboard ."
    "board side";
  column-gap: var(--layout-gap);
  row-gap: var(--board-header-gap);
  align-items: start;
}

.board-stage {
  grid-area: board;
  position: relative;
  width: min(100%, var(--board-max-size));
  container-type: inline-size;
}

.board {
  display: grid;
  grid-template-columns: repeat(var(--grid-size, 8), 1fr);
  grid-template-rows: repeat(var(--grid-size, 8), 1fr);
  gap: var(--board-gap);
  width: 100%;
  aspect-ratio: 1;
  padding: var(--board-padding);
  background: var(--grid);
  border: var(--board-border-width) solid var(--board-border-color);
  container-type: inline-size;
}

.scoreboard {
  grid-area: scoreboard;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  grid-template-areas:
    "high-score setup"
    "current-score current-score";
  align-items: center;
  row-gap: var(--scoreboard-row-gap);
  padding-block: var(--scoreboard-padding-block);
  padding-inline: var(--scoreboard-padding-inline);
}

.scoreboard b {
  color: var(--ink);
  font-weight: 700;
  line-height: 1;
}

.high-score {
  grid-area: high-score;
  display: flex;
  align-items: center;
  gap: 5px;
  justify-self: start;
  font-size: var(--high-score-value-size);
}

.current-score {
  grid-area: current-score;
  justify-self: center;
  font-size: var(--score-value-size);
}

.language-trigger {
  grid-area: setup;
  justify-self: end;
  display: grid;
  place-items: center;
  min-width: var(--language-trigger-size);
  min-height: var(--language-trigger-size);
  border-radius: var(--control-radius);
  font-size: var(--language-flag-size);
  line-height: 1;
  cursor: pointer;
}

.language-trigger:disabled { cursor: not-allowed; opacity: 0.45; }

.language-screen {
  position: fixed;
  inset: 0;
  z-index: 10;
  overflow-y: auto;
  padding:
    max(var(--page-padding), env(safe-area-inset-top))
    max(var(--page-padding), env(safe-area-inset-right))
    max(var(--page-padding), env(safe-area-inset-bottom))
    max(var(--page-padding), env(safe-area-inset-left));
  background: var(--bg);
}

.language-screen[hidden] { display: none; }

.language-screen-content {
  display: grid;
  gap: var(--language-screen-gap);
  width: min(100%, var(--board-max-size));
  margin: 0 auto;
}

.language-screen-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.language-screen-header h2 {
  margin: 0;
  font-size: 28px;
}

.language-close {
  display: grid;
  place-items: center;
  width: var(--language-trigger-size);
  height: var(--language-trigger-size);
  border-radius: var(--control-radius);
  font-size: 30px;
  line-height: 1;
  cursor: pointer;
}

.language-close:hover { background: #eef4ff; }

.language-list {
  display: grid;
  border-block: 1px solid #d8dadd;
}

.language-option {
  display: flex;
  align-items: center;
  gap: var(--language-screen-gap);
  width: 100%;
  padding: var(--language-option-padding);
  border-bottom: 1px solid #d8dadd;
  font-size: 22px;
  font-weight: 700;
  cursor: pointer;
}

.language-option:last-child { border-bottom: 0; }
.language-option:hover { background: #eef4ff; }
.language-option-flags { font-size: var(--language-flag-size); }

.current-score b {
  display: inline-block;
  transform-origin: center;
}

#score.score-bounce {
  animation:
    score-bounce-up var(--score-bounce-rise-duration) ease-out forwards,
    score-bounce-down var(--score-bounce-settle-duration) ease-in-out var(--score-bounce-rise-duration) forwards;
}

@keyframes score-bounce-up {
  to { transform: scale(var(--score-bounce-scale)); }
}

@keyframes score-bounce-down {
  from { transform: scale(var(--score-bounce-scale)); }
  to { transform: scale(1); }
}

@media (prefers-reduced-motion: reduce) {
  #score.score-bounce { animation: none; }
}

.celebration {
  position: absolute;
  inset: 0;
  z-index: 5;
  display: grid;
  place-items: center;
  color: var(--celebration-label-color);
  font-weight: 700;
  line-height: 1;
  text-align: center;
  pointer-events: none;
}

.celebration-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--celebration-gap);
  max-width: 90%;
  font-size: var(--celebration-label-size);
}

.celebration-label,
.celebration-points {
  -webkit-text-stroke: var(--celebration-outline-width) var(--celebration-outline-color);
  paint-order: stroke fill;
  text-shadow: var(--celebration-text-shadow);
}

.play-again-button {
  display: grid;
  place-items: center;
  width: var(--play-again-width);
  height: var(--play-again-height);
  border: var(--play-again-border);
  border-radius: var(--play-again-border-radius);
  background: var(--play-again-background);
  box-shadow: var(--play-again-box-shadow);
  color: #fff;
  cursor: pointer;
  pointer-events: auto;
}

.play-again-button[hidden] { display: none; }

.play-again-button:active { transform: translateY(1px); }

.play-again-icon {
  font-size: var(--play-again-icon-size);
  line-height: 1;
}

.celebration[hidden] { display: none; }

.celebration.active {
  animation: celebration-life var(--celebration-label-duration) ease-out both;
}

.celebration-points {
  color: var(--celebration-points-color);
  font-size: var(--celebration-points-size);
}

.celebration.active .celebration-points {
  animation: celebration-points-recede var(--celebration-points-duration) ease-out var(--celebration-points-delay) both;
}

.celebration.game-over {
  color: var(--game-over-label-color-1);
  animation:
    game-over-enter var(--game-over-duration) ease-out both,
    game-over-color-pulse var(--game-over-color-duration) ease-in-out var(--game-over-duration) infinite;
}

@keyframes celebration-life {
  0% { opacity: 0; transform: scale(0.9); }
  12%, 76% { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(1.04); }
}

@keyframes celebration-points-recede {
  0% { opacity: 0; transform: scale(var(--celebration-points-entry-scale)); }
  35% { opacity: 1; }
  100% { opacity: 1; transform: scale(1); }
}

@keyframes game-over-enter {
  0% { opacity: 0; transform: scale(var(--game-over-entry-scale)); }
  70% { opacity: 1; transform: scale(var(--game-over-overshoot-scale)); }
  100% { opacity: 1; transform: scale(1); }
}

@keyframes game-over-color-pulse {
  0%, 100% { color: var(--game-over-label-color-1); }
  25% { color: var(--game-over-label-color-2); }
  50% { color: var(--game-over-label-color-3); }
  75% { color: var(--game-over-label-color-4); }
}

@media (prefers-reduced-motion: reduce) {
  .celebration.active { animation-name: celebration-fade; }
  .celebration.active .celebration-points { animation-name: celebration-points-fade; }
  .celebration.game-over { animation: none; }
}

@keyframes celebration-fade {
  0% { opacity: 0; }
  12%, 76% { opacity: 1; }
  100% { opacity: 0; }
}

@keyframes celebration-points-fade {
  0%, 20% { opacity: 0; }
  38%, 100% { opacity: 1; }
}

button {
  appearance: none;
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
  color: inherit;
  font: inherit;
  line-height: inherit;
  text-align: inherit;
}

.cell-button {
  display: grid;
  place-items: center;
  border-radius: var(--control-radius);
  cursor: pointer;
  user-select: none;
}

.cell {
  --cell-background: #fbfbfb;
  --cell-border: 0 solid transparent;
  --cell-border-radius: var(--control-radius);
  --cell-box-shadow: none;
  --cell-color: var(--ink);
  display: grid;
  place-items: center;
  min-width: 0;
  min-height: 0;
  padding: 0;
  border: var(--cell-border);
  border-radius: var(--cell-border-radius);
  background: var(--cell-background);
  box-shadow: var(--cell-box-shadow);
  color: var(--cell-color);
  font-weight: 700;
  font-size: clamp(16px, 2vw, 25px);
  font-size: clamp(var(--cell-font-min), calc(var(--cell-font-scale) / var(--grid-size, 8)), var(--cell-font-max));
  line-height: 1;
}

.cell.empty:hover:not(:disabled) { background: #eef4ff; }
.cell.fixed {
  --cell-background: var(--fixed);
  cursor: default;
}
.cell.temp {
  --cell-background: var(--rack-tile-background);
  --cell-border: var(--rack-tile-border);
  --cell-box-shadow: var(--rack-tile-box-shadow);
  touch-action: none;
}

.cell.drag-drop-target {
  background: var(--drag-target-color);
}

.cell.temp.rejected {
  animation: rejected-tile-shake var(--rejected-tile-shake-duration) ease-in-out;
  transform-origin: center;
}

@keyframes rejected-tile-shake {
  0%, 100% {
    filter: grayscale(0) brightness(1);
    transform: translateX(0) rotate(0deg);
  }
  15% {
    filter: grayscale(1) brightness(var(--rejected-tile-dim));
    transform: translateX(calc(0% - var(--rejected-tile-shake-distance))) rotate(calc(0deg - var(--rejected-tile-shake-rotation)));
  }
  30% { transform: translateX(var(--rejected-tile-shake-distance)) rotate(var(--rejected-tile-shake-rotation)); }
  45% { transform: translateX(calc(0% - var(--rejected-tile-shake-distance))) rotate(calc(0deg - var(--rejected-tile-shake-rotation))); }
  60% { transform: translateX(var(--rejected-tile-shake-distance)) rotate(var(--rejected-tile-shake-rotation)); }
  75% {
    filter: grayscale(1) brightness(var(--rejected-tile-dim));
    transform: translateX(calc(0% - var(--rejected-tile-shake-distance))) rotate(calc(0deg - var(--rejected-tile-shake-rotation)));
  }
}

@media (prefers-reduced-motion: reduce) {
  .cell.temp.rejected {
    animation-name: rejected-tile-desaturate;
  }
}

@keyframes rejected-tile-desaturate {
  0%, 100% { filter: grayscale(0) brightness(1); }
  25%, 75% { filter: grayscale(1) brightness(var(--rejected-tile-dim)); }
}

.cell.highlight {
  --cell-background: var(--accepted);
  --cell-border: transparent;
  --cell-box-shadow: none;
}

.cell.round-covered {
  --cell-background: var(--round-tile-background);
  --cell-border: var(--round-tile-border);
  --cell-border-radius: var(--round-tile-border-radius);
  --cell-box-shadow: var(--round-tile-box-shadow);
  --cell-color: var(--round-tile-color);
}

.side {
  grid-area: side;
}

.ui-button {
  min-height: 38px;
  border: 1px solid #9aa0a6;
  border-radius: var(--control-radius);
  background: #ffffff;
  color: var(--ink);
  font: inherit;
  padding: 8px 10px;
  font-weight: 700;
  text-align: center;
  cursor: pointer;
}

.ui-button:hover:not(:disabled) { background: #eef4ff; }
.ui-button:disabled { cursor: not-allowed; opacity: 0.45; }

.rack-section {
  display: grid;
  gap: 10px;
}

.rack-actions {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--control-gap);
  container-type: inline-size;
}

.rack-actions .ui-button {
  min-width: 0;
  padding-inline: 4px;
  font-size: clamp(12px, 4.5cqi, 16px);
}

.rack {
  display: grid;
  grid-template-columns: repeat(var(--rack-size), minmax(0, 1fr));
  gap: var(--rack-gap);
  container-type: inline-size;
}

.rack:empty::before {
  content: "";
  width: 100%;
  aspect-ratio: 1;
}

.rack-tile {
  --rack-tile-scale: 1;
  width: 100%;
  height: auto;
  min-height: 0;
  aspect-ratio: 1;
  padding: 0;
  border: var(--rack-tile-border);
  border-radius: var(--rack-tile-border-radius);
  background: var(--rack-tile-background);
  color: var(--rack-tile-color);
  box-shadow: var(--rack-tile-box-shadow);
  font-weight: 700;
  font-size: 21px;
  font-size: clamp(var(--rack-font-min), calc(var(--rack-font-scale) / var(--rack-size)), var(--rack-font-max));
  line-height: 1;
  transform: scale(var(--rack-tile-scale));
  transition: transform 0.1s linear;
  touch-action: none;
}

.rack-tile:hover:not(:disabled) {
  --rack-tile-scale: 1.1;
}

.rack.dragging .rack-tile {
  --rack-tile-scale: 1;
  transition: none;
}

.rack-tile[aria-pressed="true"] {
  --rack-tile-background: var(--rack-tile-active);
  --rack-tile-scale: 1.1;
}

.rack-tile:disabled { opacity: 0.45; }

.rack-tile.in-rack-transition {
  position: relative;
  z-index: 2;
  pointer-events: none;
  will-change: transform;
}

.rack-tile.drag-insert-before,
.rack-tile.drag-insert-after {
  position: relative;
}

.rack-tile.drag-insert-before::after,
.rack-tile.drag-insert-after::after {
  content: "";
  position: absolute;
  top: -4px;
  bottom: -4px;
  width: var(--rack-insertion-width);
  border-radius: var(--rack-insertion-width);
  background: var(--drag-target-color);
}

.rack-tile.drag-insert-before::after { left: var(--rack-insertion-offset); }
.rack-tile.drag-insert-after::after { right: var(--rack-insertion-offset); }

.rack-tile.drag-source,
.cell.temp.drag-source {
  background: var(--drag-source-background);
  border-color: var(--drag-source-border-color);
  color: var(--drag-source-color);
  box-shadow: none;
}

.drag-tile {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  margin: 0;
  padding: 0;
  border: var(--rack-tile-border);
  border-radius: var(--rack-tile-border-radius);
  background: var(--rack-tile-background);
  color: var(--rack-tile-color);
  box-shadow: var(--rack-tile-box-shadow);
  font-weight: 700;
  line-height: 1;
  pointer-events: none;
  will-change: transform;
}

.drag-tile[hidden] { display: none; }

@media (max-width: 740px) { /* 740 -> 8x8 grid, adjust when changing GRID_SIZE */
  main { padding: var(--page-padding-small); }
  .layout {
    grid-template-columns: 1fr;
    grid-template-areas:
      "scoreboard"
      "board"
      "side";
  }
  .side { margin-top: calc(var(--layout-gap) - var(--board-header-gap)); }
  .board { width: 100%; }
}