:root {
  --radius: 6px;
  --bg: #faf8ef;
  --text: #776e65;
  --board-bg: #bbada0;
  --cell-bg: rgba(238, 228, 218, 0.35);
  --p1: #3d7ea6;
  --p2: #c0504d;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: "Clear Sans", "Helvetica Neue", Arial, sans-serif;
  display: flex;
  justify-content: center;
  overscroll-behavior: none; /* no pull-to-refresh / bounce when installed as an app */
  -webkit-tap-highlight-color: transparent;
}

.container {
  width: min(92vw, 480px);
  /* Keep clear of notches and home indicators on phones. */
  padding: max(24px, env(safe-area-inset-top)) 0 max(24px, env(safe-area-inset-bottom));
}

.container.versus {
  width: min(96vw, 860px);
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.title {
  font-size: clamp(48px, 14vw, 72px);
  margin: 0;
  font-weight: bold;
}

.modes {
  display: flex;
  gap: 4px;
  background: #e4dacd;
  padding: 4px;
  border-radius: var(--radius);
}

.mode-btn {
  background: transparent;
  color: var(--text);
  border: none;
  border-radius: 4px;
  padding: 8px 12px;
  font-size: 14px;
  font-weight: bold;
  cursor: pointer;
  font-family: inherit;
}

.mode-btn.active {
  background: #8f7a66;
  color: #f9f6f2;
}

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 16px 0;
  gap: 12px;
}

.intro {
  margin: 0;
  line-height: 1.4;
}

.btn {
  background: #8f7a66;
  color: #f9f6f2;
  border: none;
  border-radius: var(--radius);
  padding: 10px 18px;
  font-size: 16px;
  font-weight: bold;
  cursor: pointer;
  font-family: inherit;
  white-space: nowrap;
}

.btn:hover {
  background: #9f8b77;
}

/* ---------- Arena & panels ---------- */

.arena {
  display: flex;
  justify-content: space-between;
  gap: 24px;
}

.panel {
  --board: min(92vw, 480px);
  --gap: calc(var(--board) * 0.03);
}

/* Online: your board is the big one, the opponent's is a small live view. */
.arena.versus {
  justify-content: center;
  align-items: flex-start;
}

.arena.versus .panel.me {
  --board: min(60vw, 540px);
}

.arena.versus .panel.opponent {
  --board: min(28vw, 260px);
}

.panel.opponent .overlay-buttons {
  display: none;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  gap: 8px;
}

.player-name {
  font-size: clamp(16px, 3vw, 24px);
  font-weight: bold;
}

.panel.me .player-name { color: var(--p1); }
.panel.opponent .player-name { color: var(--p2); }

.scores {
  display: flex;
  gap: 6px;
}

.score-box {
  background: var(--board-bg);
  border-radius: var(--radius);
  padding: 6px 16px;
  min-width: 72px;
  text-align: center;
  color: #fff;
  display: flex;
  flex-direction: column;
}

.score-label {
  font-size: 12px;
  text-transform: uppercase;
  color: #eee4da;
  font-weight: bold;
}

.score-value {
  font-size: 22px;
  font-weight: bold;
}

.keys {
  margin: 12px 0 0;
  text-align: center;
  line-height: 1.5;
}

.keys.away {
  color: var(--p2);
  font-weight: bold;
}

/* ---------- Board ---------- */

.board {
  --size: 4;
  position: relative;
  width: var(--board);
  height: var(--board);
  background: var(--board-bg);
  border-radius: var(--radius);
  padding: var(--gap);
  touch-action: none;
  user-select: none;
}

.grid {
  display: grid;
  grid-template-columns: repeat(var(--size), 1fr);
  grid-template-rows: repeat(var(--size), 1fr);
  gap: var(--gap);
  width: 100%;
  height: 100%;
}

.cell {
  background: var(--cell-bg);
  border-radius: var(--radius);
}

.tiles {
  position: absolute;
  inset: var(--gap);
}

/* Outer element handles position (slide), inner handles pop animations. */
.tile {
  position: absolute;
  top: 0;
  left: 0;
  width: calc((100% - (var(--size) - 1) * var(--gap)) / var(--size));
  height: calc((100% - (var(--size) - 1) * var(--gap)) / var(--size));
  transform: translate(calc(var(--c) * (100% + var(--gap))), calc(var(--r) * (100% + var(--gap))));
  transition: transform 100ms ease-in-out;
  z-index: 2;
}

.tile.dying {
  z-index: 1;
}

.tile-inner {
  width: 100%;
  height: 100%;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  font-size: calc(var(--board) * 0.11);
  background: #eee4da;
  color: var(--text);
}

.tile.new .tile-inner {
  animation: appear 200ms ease 100ms backwards;
}

.tile.merged .tile-inner {
  animation: pop 200ms ease 100ms backwards;
}

.tile.stone.new .tile-inner {
  animation: drop 300ms ease-in 100ms backwards;
}

.tile.stone.dying .tile-inner {
  animation: crumble 200ms ease forwards;
}

@keyframes appear {
  from { opacity: 0; transform: scale(0); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes pop {
  0% { transform: scale(0); }
  50% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

@keyframes drop {
  from { opacity: 0; transform: scale(1.8); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes crumble {
  to { opacity: 0; transform: scale(0.6) rotate(15deg); }
}

/* ---------- Tile colors ---------- */

.tile[data-value="2"] .tile-inner { background: #eee4da; }
.tile[data-value="4"] .tile-inner { background: #ede0c8; }
.tile[data-value="8"] .tile-inner { background: #f2b179; color: #f9f6f2; }
.tile[data-value="16"] .tile-inner { background: #f59563; color: #f9f6f2; }
.tile[data-value="32"] .tile-inner { background: #f67c5f; color: #f9f6f2; }
.tile[data-value="64"] .tile-inner { background: #f65e3b; color: #f9f6f2; }
.tile[data-value="128"] .tile-inner { background: #edcf72; color: #f9f6f2; box-shadow: 0 0 20px 4px rgba(243, 215, 116, 0.3); }
.tile[data-value="256"] .tile-inner { background: #edcc61; color: #f9f6f2; box-shadow: 0 0 20px 4px rgba(243, 215, 116, 0.4); }
.tile[data-value="512"] .tile-inner { background: #edc850; color: #f9f6f2; box-shadow: 0 0 20px 4px rgba(243, 215, 116, 0.5); }
.tile[data-value="1024"] .tile-inner { background: #edc53f; color: #f9f6f2; box-shadow: 0 0 20px 4px rgba(243, 215, 116, 0.6); }
.tile[data-value="2048"] .tile-inner { background: #edc22e; color: #f9f6f2; box-shadow: 0 0 24px 6px rgba(243, 215, 116, 0.7); }
.tile.super .tile-inner { background: #3c3a32; color: #f9f6f2; }

.tile.stone .tile-inner {
  background: repeating-linear-gradient(45deg, #5d5750, #5d5750 6px, #534d47 6px, #534d47 12px);
  color: rgba(249, 246, 242, 0.75);
  font-size: calc(var(--board) * 0.06);
  box-shadow: inset 0 0 0 3px #45403b;
}

.tile.digits-3 .tile-inner { font-size: calc(var(--board) * 0.09); }
.tile.digits-4 .tile-inner { font-size: calc(var(--board) * 0.07); }
.tile.digits-5 .tile-inner { font-size: calc(var(--board) * 0.055); }

/* ---------- Overlay ---------- */

.overlay {
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: rgba(238, 228, 218, 0.73);
  z-index: 10;
  animation: fade-in 600ms ease 400ms backwards;
}

.overlay.visible {
  display: flex;
}

.overlay.won {
  background: rgba(237, 194, 46, 0.5);
  color: #f9f6f2;
}

.overlay-text {
  margin: 0;
  font-size: calc(var(--board) * 0.12);
  font-weight: bold;
  text-align: center;
}

.overlay-sub {
  margin: -8px 16px 0;
  font-size: 16px;
  font-weight: bold;
  text-align: center;
}

.overlay-buttons {
  display: flex;
  gap: 8px;
}

@keyframes fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

.bot-setup {
  grid-template-columns: 1fr;
}

.quick-card {
  grid-column: 1 / -1;
}

.quick-lonely {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px;
  border-radius: var(--radius);
  background: #faf8ef;
  animation: fade-in 300ms ease;
}

.quick-lonely p {
  font-weight: bold;
}

.btn-quiet {
  background: transparent;
  color: #8f7a66;
  box-shadow: inset 0 0 0 2px #8f7a66;
}

.btn-quiet:hover {
  background: #f3ece4;
}

.name-row {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 10px;
}

.name-row .pick-label {
  margin: 0;
  white-space: nowrap;
}

.name-input {
  flex: 1;
  min-width: 0;
  max-width: 260px;
  padding: 8px 10px;
  border: 2px solid #bbada0;
  border-radius: var(--radius);
  background: #faf8ef;
  color: #3c3a32;
  font-family: inherit;
  font-size: 16px; /* 16px+ stops phones zooming in on focus */
  font-weight: bold;
}

.name-input::placeholder {
  color: #c9bdb1;
  font-weight: normal;
}

.name-input:focus {
  outline: none;
  border-color: #8f7a66;
}

.name-input.invalid {
  border-color: var(--p2);
}

.name-warning {
  grid-column: 1 / -1;
  margin: -8px 0 0;
  color: var(--p2);
  font-size: 14px;
  font-weight: bold;
}

/* ---------- QR scanner ---------- */

.scanner {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: #000;
  display: flex;
  flex-direction: column;
}

.scanner video {
  flex: 1;
  width: 100%;
  min-height: 0;
  object-fit: cover;
}

.scanner-frame {
  position: absolute;
  top: 40%;
  left: 50%;
  width: min(65vw, 65vh, 320px);
  aspect-ratio: 1;
  transform: translate(-50%, -50%);
  border: 4px solid rgba(255, 255, 255, 0.9);
  border-radius: 18px;
  box-shadow: 0 0 0 9999px rgba(0, 0, 0, 0.35);
  pointer-events: none;
}

.scanner-bar {
  position: relative;
  padding: 16px 20px max(20px, env(safe-area-inset-bottom));
  background: var(--bg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  text-align: center;
}

.scanner-bar p {
  margin: 0;
  font-weight: bold;
  line-height: 1.4;
}

.pick-label {
  font-size: 12px;
  font-weight: bold;
  text-transform: uppercase;
  margin-bottom: -6px;
}

.lobby-privacy {
  grid-column: 1 / -1;
  margin: 0;
  text-align: center;
  font-size: 13px;
}

.lobby-privacy a {
  color: #a39588;
}

/* ---------- Online lobby ---------- */

.lobby {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.lobby-card {
  background: #eee4da;
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.lobby-card h2 {
  margin: 0;
  font-size: 22px;
}

.lobby-card p {
  margin: 0;
  line-height: 1.4;
}

.rules-pick {
  display: flex;
  gap: 4px;
  background: #e4dacd;
  padding: 4px;
  border-radius: var(--radius);
}

.rules-pick input {
  position: absolute;
  opacity: 0;
}

.rules-pick span {
  display: block;
  padding: 6px 14px;
  border-radius: 4px;
  font-weight: bold;
  cursor: pointer;
}

.rules-pick input:checked + span {
  background: #8f7a66;
  color: #f9f6f2;
}

.rules-pick input:focus-visible + span {
  outline: 2px solid var(--p1);
}

.create-controls {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.room-info {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  width: 100%;
}

.room-code-row {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.room-qr {
  width: 180px;
  background: #fff;
  border-radius: var(--radius);
  padding: 6px;
  line-height: 0;
}

.room-qr svg {
  width: 100%;
  height: auto;
}

.room-qr-hint {
  font-size: 14px;
  text-align: center;
}

.invite-link {
  width: 100%;
  padding: 6px 8px;
  border: 2px solid #bbada0;
  border-radius: var(--radius);
  background: #faf8ef;
  color: var(--text);
  font-family: inherit;
  font-size: 13px;
}

.invite-link:focus {
  outline: none;
  border-color: #8f7a66;
}

.share-buttons {
  display: flex;
  gap: 8px;
}

.room-label {
  font-size: 12px;
  text-transform: uppercase;
  font-weight: bold;
}

.room-code,
.code-input {
  font-family: "Consolas", "Courier New", monospace;
  font-size: 28px;
  font-weight: bold;
  letter-spacing: 4px;
  color: #3c3a32;
}

.code-input {
  width: 100%;
  max-width: 200px;
  padding: 6px 10px;
  border: 2px solid #bbada0;
  border-radius: var(--radius);
  background: #faf8ef;
  text-transform: uppercase;
}

.code-input::placeholder {
  color: #d6cdc4;
}

.code-input:focus {
  outline: none;
  border-color: #8f7a66;
}

.btn:disabled {
  opacity: 0.5;
  cursor: default;
}

.btn-small {
  padding: 6px 12px;
  font-size: 14px;
}

.lobby-status {
  grid-column: 1 / -1;
  margin: 0;
  min-height: 1.4em;
  font-weight: bold;
  text-align: center;
}

.room-tag {
  display: inline-block;
  margin-left: 6px;
  padding: 1px 8px;
  border-radius: 4px;
  background: #e4dacd;
  font-family: "Consolas", "Courier New", monospace;
  font-weight: bold;
  white-space: nowrap;
}

@media (max-width: 640px) {
  .lobby {
    grid-template-columns: 1fr;
  }
  /* Phones: opponent becomes a compact strip above your full-width board,
     and the page chrome is tightened so the board gets as much height as possible. */
  .container.versus .title {
    font-size: 40px;
  }
  .container.versus .toolbar {
    margin: 10px 0;
  }
  .container.versus .intro {
    font-size: 14px;
  }
  .arena.versus {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
  }
  .arena.versus .panel.me {
    --board: 96vw; /* full width of the versus container; fitBoard() may shrink it */
  }
  .arena.versus .panel.me .board {
    margin: 0 auto;
  }
  .arena.versus .panel.me .panel-header {
    margin-bottom: 6px;
  }
  .arena.versus .panel.me .keys {
    margin-top: 6px;
    font-size: 13px;
  }
  .arena.versus .panel.opponent {
    --board: 26vw;
    order: -1;
    display: grid;
    grid-template-columns: auto 1fr;
    grid-template-areas: "board header" "board keys";
    column-gap: 12px;
    align-items: center;
  }
  .panel.opponent .board {
    grid-area: board;
  }
  .panel.opponent .panel-header {
    grid-area: header;
    flex-direction: column;
    align-items: flex-start;
    align-self: end;
    margin: 0;
  }
  .panel.opponent .keys {
    grid-area: keys;
    align-self: start;
    text-align: left;
    margin: 4px 0 0;
    font-size: 13px;
  }
}