:root{
  --bg:#f5f4f0; --surface:#fbfbf9; --panel:#ffffff; --panel-soft:#f7f6f2;
  --ink:#1c1c1a; --ink-hover:#3a3935; --ink-2:#55534d; --sub:#7a776f; --muted:#8a877f;
  --line:#e3e1db; --line-2:#dcdad3; --line-3:#efeee9; --hover:#efeee9; --soft:#f3f2ee; --track:#ebe9e3;
  --accent:#1c1c1a;
  --font:"IBM Plex Sans KR",sans-serif; --mono:"JetBrains Mono",monospace;
}
*{box-sizing:border-box}
[hidden]{display:none !important}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font);-webkit-font-smoothing:antialiased}
button{font:inherit;color:inherit}
.mono-label{font-family:var(--mono);font-size:11px;letter-spacing:.12em;color:var(--muted)}
.app{min-height:calc(100vh - 48px);display:flex;flex-direction:column}
.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:16px 28px;border-bottom:1px solid var(--line);background:var(--surface);flex-wrap:wrap}
.brand{display:flex;align-items:baseline;gap:14px;min-width:0;flex-wrap:wrap}
.home{font-size:13px;color:var(--ink-2);text-decoration:none}
.home:hover{color:var(--ink)}
.brand-title{font-size:17px;font-weight:700;letter-spacing:-.01em}
.btn{height:36px;padding:0 14px;background:transparent;border:1px solid var(--line-2);border-radius:999px;font-size:13px;cursor:pointer}
.btn:hover{background:var(--hover)}
.btn:disabled{opacity:.4;cursor:default}
.btn:disabled:hover{background:transparent}
.btn--solid{background:var(--ink);color:#fff;border:none;font-weight:500}
.btn--solid:hover{background:var(--ink-hover)}
.text-input{height:40px;padding:0 12px;background:var(--surface);border:1px solid var(--line-2);border-radius:8px;font:inherit;font-size:14px;color:var(--ink)}
@media (max-width:640px){ .topbar{padding:14px 16px} }

/* ---------- 게임 공통 셸 ---------- */
.actions{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.btn--accent{background:var(--accent);color:#fff;border:none;font-weight:500}
.btn--accent:hover{background:var(--accent);filter:brightness(1.08)}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.game{flex:1;display:flex;flex-wrap:wrap;align-items:stretch;min-height:0}
.stage{flex:999 1 420px;min-width:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:20px;padding:40px 28px}
.side{flex:1 1 300px;min-width:0;max-width:100%;border-left:1px solid var(--line);background:var(--panel);padding:28px 24px 40px;display:flex;flex-direction:column;gap:28px}
.group{display:flex;flex-direction:column;gap:12px}
.group + .group{border-top:1px solid var(--line-3);padding-top:24px}
.rules{margin:0;padding:0;list-style:none;display:flex;flex-direction:column;gap:8px;font-size:13px;color:var(--ink-2);line-height:1.6;counter-reset:rule}
.rules li{display:flex;gap:10px}
.rules li::before{counter-increment:rule;content:counter(rule,decimal-leading-zero);font-family:var(--mono);font-size:11px;color:var(--accent);padding-top:3px;flex-shrink:0}
.keys{display:flex;flex-direction:column;gap:8px;font-size:12px;color:var(--ink-2)}
.keys div{display:flex;justify-content:space-between;align-items:center;gap:12px}
.kbd{display:inline-block;font-family:var(--mono);font-size:11px;line-height:1.4;padding:1px 6px;border:1px solid var(--line-2);border-bottom-width:2px;border-radius:5px;background:var(--surface);color:var(--ink)}
.best-card{display:flex;align-items:baseline;justify-content:space-between;gap:12px;padding:16px;border-radius:12px;background:var(--panel-soft)}
.best-val{font-family:var(--mono);font-size:28px;font-weight:500;letter-spacing:-.02em}
.seg{display:flex;background:var(--soft);border-radius:999px;padding:3px;gap:2px}
.seg-btn{flex:1;height:30px;padding:0 10px;background:transparent;color:var(--sub);border:none;border-radius:999px;font-size:12px;cursor:pointer;white-space:nowrap}
.seg-btn.is-active{background:#fff;color:var(--ink);box-shadow:0 1px 3px rgba(0,0,0,.12)}
.link-btn{padding:0;background:none;border:none;font-size:12px;color:var(--muted);text-decoration:underline;text-underline-offset:3px;cursor:pointer}
@media (max-width:640px){
  .stage{padding:24px 16px}
  .side{border-left:none;border-top:1px solid var(--line);padding:24px 16px 40px}
}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.01ms !important;animation-iteration-count:1 !important;transition-duration:.01ms !important}
}

/* ---------- 2048 ---------- */
:root{--accent:#ff5a1f;--gap:12px;--speed:110ms}
.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.undo-count{display:inline-flex;align-items:center;justify-content:center;min-width:18px;height:18px;margin-left:4px;padding:0 5px;border-radius:999px;background:var(--accent);color:#fff;font-family:var(--mono);font-size:10px}
#undo:disabled .undo-count{background:var(--muted)}

.scorebar{width:100%;max-width:480px;display:flex;align-items:flex-end;justify-content:space-between;gap:12px}
.logo{font-family:var(--mono);font-weight:800;font-size:52px;line-height:.9;letter-spacing:-.06em;color:var(--ink)}
.logo::after{content:"";display:block;width:100%;height:6px;margin-top:8px;border-radius:999px;background:linear-gradient(90deg,#ffd166,#ff8a3d,#ff5a1f,#ff2e6d)}
.scores{display:flex;gap:8px}
.score-box{position:relative;display:flex;flex-direction:column;align-items:flex-end;gap:2px;min-width:92px;padding:10px 14px;border-radius:14px;background:var(--panel);border:1px solid var(--line)}
.score-box--best{background:var(--ink);border-color:var(--ink)}
.score-box--best .mono-label{color:#a8a59c}
.score-box--best .score-val{color:#fff}
.score-val{font-family:var(--mono);font-size:22px;font-weight:700;line-height:1.1;font-variant-numeric:tabular-nums}
.score-plus{position:absolute;right:14px;top:-4px;font-family:var(--mono);font-size:14px;font-weight:700;color:var(--accent);opacity:0;pointer-events:none}
.score-plus.is-on{animation:plus .7s ease-out}

.board{position:relative;width:min(100%,480px);aspect-ratio:1;padding:var(--gap);border-radius:22px;background:#2a2723;box-shadow:0 2px 0 #11100e,0 30px 60px -24px rgba(255,90,31,.45);touch-action:none;user-select:none;-webkit-user-select:none;outline:none}
.board:focus-visible{box-shadow:0 0 0 3px var(--accent),0 30px 60px -24px rgba(255,90,31,.45)}
.grid{position:absolute;inset:var(--gap);display:grid;grid-template-columns:repeat(4,1fr);grid-template-rows:repeat(4,1fr);gap:var(--gap)}
.grid span{border-radius:12px;background:#3a3631}
.tiles{position:absolute;inset:var(--gap)}
.tile{position:absolute;left:0;top:0;width:calc((100% - 3 * var(--gap)) / 4);height:calc((100% - 3 * var(--gap)) / 4);transform:translate(calc(var(--c) * (100% + var(--gap))),calc(var(--r) * (100% + var(--gap))));transition:transform var(--speed) ease-out;z-index:1}
.tile.is-merged{z-index:3}
.tile.is-gone{z-index:0}
.tile-inner{width:100%;height:100%;display:flex;align-items:center;justify-content:center;border-radius:12px;font-family:var(--mono);font-weight:800;letter-spacing:-.04em;font-size:clamp(22px,8vw,44px);background:var(--tb);color:var(--tc);box-shadow:inset 0 -3px 0 rgba(0,0,0,.12)}
.tile.is-new .tile-inner{animation:appear 180ms var(--speed) ease-out backwards}
.tile.is-merged .tile-inner{animation:merge 200ms var(--speed) ease-out backwards}
.tile[data-d="3"] .tile-inner{font-size:clamp(20px,7vw,38px)}
.tile[data-d="4"] .tile-inner{font-size:clamp(16px,5.4vw,30px)}
.tile[data-d="5"] .tile-inner{font-size:clamp(13px,4.2vw,24px)}
.tile[data-d="6"] .tile-inner{font-size:clamp(11px,3.4vw,20px)}

.v2{--tb:#f4efe7;--tc:#3a3631}
.v4{--tb:#f1e2c9;--tc:#3a3631}
.v8{--tb:#ffc58f;--tc:#3a1d08}
.v16{--tb:#ffa25e;--tc:#fff}
.v32{--tb:#ff7d3a;--tc:#fff}
.v64{--tb:#ff5a1f;--tc:#fff}
.v128{--tb:#ffd23f;--tc:#3a2a00}
.v256{--tb:#ffc21a;--tc:#3a2a00}
.v512{--tb:#ff2e6d;--tc:#fff}
.v1024{--tb:#d6146a;--tc:#fff}
.v2048{--tb:#ffffff;--tc:#ff5a1f}
.v2048 .tile-inner{box-shadow:0 0 0 3px #ff5a1f inset,0 0 28px rgba(255,90,31,.8)}
.vbig{--tb:#111;--tc:#ffd23f}

.overlay{position:absolute;inset:0;z-index:10;display:flex;align-items:center;justify-content:center;padding:16px;border-radius:22px;background:rgba(42,39,35,.72);backdrop-filter:blur(3px);-webkit-backdrop-filter:blur(3px);animation:fadeIn .3s ease-out}
.overlay.is-win{background:rgba(255,90,31,.78)}
.overlay-card{display:flex;flex-direction:column;align-items:center;gap:8px;padding:24px 26px;max-width:100%;background:var(--panel);border-radius:18px;text-align:center;box-shadow:0 24px 60px rgba(0,0,0,.3);animation:rise .35s cubic-bezier(.2,1.2,.4,1)}
.overlay-title{font-size:20px;letter-spacing:-.01em}
.overlay-sub{margin:0;font-size:13px;color:var(--sub)}
.overlay-actions{display:flex;gap:8px;margin-top:8px;flex-wrap:wrap;justify-content:center}
.overlay-actions .btn{height:40px;padding:0 18px}
.stage-hint{margin:0;font-size:13px;color:var(--muted)}

.ladder{display:flex;flex-wrap:wrap;gap:4px}
.ladder span{display:flex;align-items:center;justify-content:center;height:28px;padding:0 8px;border-radius:7px;font-family:var(--mono);font-size:11px;font-weight:700;background:var(--tb);color:var(--tc);opacity:.35;transition:opacity .2s}
.ladder span.is-reached{opacity:1}
.ladder .v2048{box-shadow:inset 0 0 0 1.5px var(--accent)}
.side-note{margin:0;font-size:12px;color:var(--muted);line-height:1.6}

@keyframes appear{from{transform:scale(0);opacity:0}to{transform:scale(1);opacity:1}}
@keyframes merge{0%{opacity:0;transform:scale(.6)}45%{opacity:1;transform:scale(1.18)}100%{opacity:1;transform:scale(1)}}
@keyframes plus{0%{opacity:1;transform:translateY(0)}100%{opacity:0;transform:translateY(-26px)}}
@keyframes fadeIn{from{opacity:0}to{opacity:1}}
@keyframes rise{from{opacity:0;transform:translateY(16px) scale(.96)}to{opacity:1;transform:none}}
@media (max-width:640px){
  :root{--gap:8px}
  .board{border-radius:18px}
  .tile-inner,.grid span{border-radius:9px}
  .logo{font-size:40px}
  .score-box{min-width:76px;padding:8px 10px}
  .score-val{font-size:18px}
}

/* 다크 모드 (인쇄는 라이트 그대로) */
@media screen{
  :root[data-theme="dark"]{
    color-scheme:dark;
    --bg:#141318; --surface:#1a1920; --panel:#1f1e26; --panel-soft:#24232c;
    --ink:#ecebf0; --ink-hover:#ffffff; --ink-2:#c9c7d1; --sub:#a09eab; --muted:#8a8895;
    --line:#2e2d36; --line-2:#393843; --line-3:#26252d; --hover:#2a2932; --soft:#26252d; --track:#34333d;
    --accent:#ff6a33; --accent-soft:rgba(255,106,51,.16);
  }
  :root[data-theme="dark"] .btn--solid{color:var(--bg)}
  :root[data-theme="dark"] .seg-btn.is-active{background:var(--track);color:var(--ink);box-shadow:0 1px 3px rgba(0,0,0,.4)}
  :root[data-theme="dark"] .score-box--best{background:var(--panel-soft);border-color:var(--accent)}
  :root[data-theme="dark"] .score-box--best .mono-label{color:var(--accent)}
  :root[data-theme="dark"] .score-box--best .score-val{color:var(--ink)}
  :root[data-theme="dark"] .board{box-shadow:0 0 0 1px #3a3631,0 2px 0 #0b0a09,0 30px 60px -24px rgba(255,90,31,.35)}
  :root[data-theme="dark"] .board:focus-visible{box-shadow:0 0 0 3px var(--accent),0 30px 60px -24px rgba(255,90,31,.35)}
  :root[data-theme="dark"] .overlay-card{box-shadow:0 24px 60px rgba(0,0,0,.5)}
  :root[data-theme="dark"] .ladder span{opacity:.3}
  :root[data-theme="dark"] .ladder span.is-reached{opacity:1}
}