/* 2315 MOON_2048 — 레이아웃·컴포넌트
 * 극단 미니멀 모노크롬. 순백·헤어라인·여백·그림자 없음. 타일 값=무채 명도 스케일.
 * Inter + JetBrains Mono. 라이트 기본 + 다크 토글. (형제 2311·2312와 통일)
 */
* { box-sizing: border-box; }
/* hidden 속성은 항상 우선 — .overlay/.board-cover/.side-panel 의 display 지정이 [hidden]을 덮지 않도록 */
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color: var(--ink);
  background-color: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { font-weight: 700; line-height: 1.25; letter-spacing: -0.01em; }
.mono, .timer, .score-num, .big-num { font-family: 'JetBrains Mono', ui-monospace, monospace; }

.wrap { width: 100%; max-width: 1040px; margin: 0 auto; padding: 0 18px; }
.sr-title, .sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* ---------- 헤더 ---------- */
.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--surface);
  position: sticky; top: 0; z-index: 30;
}
.header-in { display: flex; align-items: center; gap: 16px; height: 58px; }
.brand { display: flex; align-items: center; gap: 9px; font-weight: 700; font-size: 18px; letter-spacing: -0.02em; }
.brand .mark {
  display: inline-grid; place-items: center; width: 28px; height: 28px;
  border: 1px solid var(--line-strong); border-radius: 6px;
  font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 10px; font-weight: 700;
  color: var(--ink); letter-spacing: -0.5px;
}
.header-nav { display: flex; gap: 4px; margin-left: 10px; flex: 1; }
.header-nav a {
  padding: 7px 11px; font-size: 14px; color: var(--ink-2); border-radius: 6px; font-weight: 600;
}
.header-nav a:hover { color: var(--ink); background: var(--surface-2); }
.header-tools { display: flex; align-items: center; gap: 8px; }
.icon-btn {
  display: inline-grid; place-items: center; width: 36px; height: 36px;
  border: 1px solid var(--line); background: var(--surface); color: var(--ink-2);
  border-radius: 7px; cursor: pointer; font-size: 15px;
}
.icon-btn:hover { color: var(--ink); border-color: var(--line-strong); }
.lang-select {
  height: 36px; border: 1px solid var(--line); background: var(--surface); color: var(--ink-2);
  border-radius: 7px; padding: 0 8px; font-size: 13px; font-family: inherit; cursor: pointer; max-width: 130px;
}

/* ---------- 게임 메인 ---------- */
.play-main { padding: 16px 0 30px; }
.play-area { max-width: 520px; margin: 0 auto; }

/* 점수판 */
.score-bar {
  display: flex; align-items: stretch; gap: 10px; margin-bottom: 14px;
}
.score-box {
  flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center;
  padding: 8px 10px; border: 1px solid var(--line); border-radius: 10px; background: var(--surface);
  min-width: 0;
}
.score-box .lbl {
  font-size: 10px; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-3);
}
.score-box .score-num { font-size: 22px; font-weight: 700; color: var(--ink); font-variant-numeric: tabular-nums; line-height: 1.2; }
.score-box .gain { color: var(--ink-2); font-size: 12px; }
.score-actions { display: flex; gap: 8px; }
.score-actions .icon-btn { width: 42px; height: 100%; }

/* 보드 — 배경 셀(grid) 위에 타일을 절대위치로 얹어 슬라이드 애니메이션 */
.board-wrap { position: relative; margin: 0 auto; }
.board {
  --gap: 8px;
  position: relative;
  display: grid; gap: var(--gap); padding: var(--gap);
  background: var(--board-bg); border: 1px solid var(--line-strong); border-radius: 10px;
  aspect-ratio: 1; width: 100%;
  touch-action: none; user-select: none; -webkit-user-select: none;
}
.cell {
  background: var(--cell-empty); border-radius: 6px; min-width: 0;
}
/* 타일: 보드 기준 절대위치. left/top 트랜지션으로 미끄러지고, transform(scale)은 등장·병합 팝에 독립 사용 */
.tile {
  position: absolute; left: 0; top: 0;
  display: grid; place-items: center;
  font-family: 'JetBrains Mono', ui-monospace, monospace;
  font-weight: 700; font-variant-numeric: tabular-nums; line-height: 1;
  border-radius: 6px; letter-spacing: -0.02em;
  font-size: calc(var(--tile, 80px) * 0.42);   /* 1~2자리 기본 */
  transition: left .12s ease, top .12s ease;
  will-change: left, top;
}
.tile.d2 { font-size: calc(var(--tile, 80px) * 0.32); }   /* 3자리(128·256·512) */
.tile.d3 { font-size: calc(var(--tile, 80px) * 0.24); }   /* 4자리(1024·2048·4096·8192) */
.tile.d4 { font-size: calc(var(--tile, 80px) * 0.19); }   /* 5자리 이상 */
.tile.spawn { animation: pop-in .14s ease; }
.tile.merge { animation: pop-merge .16s ease; }
@keyframes pop-in { 0% { transform: scale(0); } 100% { transform: scale(1); } }
@keyframes pop-merge { 0% { transform: scale(1); } 50% { transform: scale(1.16); } 100% { transform: scale(1); } }
@media (prefers-reduced-motion: reduce) {
  .tile { transition: none; }
  .tile.spawn, .tile.merge { animation: none; }
}

.tile.v2 { background: var(--t2); color: var(--t2f); }
.tile.v4 { background: var(--t4); color: var(--t4f); }
.tile.v8 { background: var(--t8); color: var(--t8f); }
.tile.v16 { background: var(--t16); color: var(--t16f); }
.tile.v32 { background: var(--t32); color: var(--t32f); }
.tile.v64 { background: var(--t64); color: var(--t64f); }
.tile.v128 { background: var(--t128); color: var(--t128f); }
.tile.v256 { background: var(--t256); color: var(--t256f); }
.tile.v512 { background: var(--t512); color: var(--t512f); }
.tile.v1024 { background: var(--t1024); color: var(--t1024f); }
.tile.v2048 { background: var(--t2048); color: var(--t2048f); }
.tile.v4096 { background: var(--t4096); color: var(--t4096f); }
.tile.vbig { background: var(--tbig); color: var(--tbigf); }

/* 오버레이 커버(게임오버·승리·일시정지) */
.board-cover {
  position: absolute; inset: 0; display: grid; place-items: center; gap: 12px;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  border-radius: 10px; z-index: 5; text-align: center; padding: 20px;
}
.board-cover .cover-title { font-size: 26px; font-weight: 800; letter-spacing: -0.02em; }
.board-cover .cover-sub { color: var(--ink-2); font-size: 14px; margin-top: -6px; }
.board-cover .cover-actions { display: flex; gap: 10px; flex-wrap: wrap; justify-content: center; }

/* 힌트(조작 안내) */
.play-hint {
  margin: 14px auto 0; text-align: center; color: var(--ink-3); font-size: 12.5px;
}

/* ---------- 광고 (애드핏 규정: 래퍼 border-radius/overflow 금지) ---------- */
.ad-wrap { margin: 26px auto 4px; display: flex; justify-content: center; }
.ad-grid { display: flex; flex-direction: column; align-items: center; gap: 14px; width: 100%; max-width: 672px; margin: 0 auto; }
.ad-grid[data-ad-layout="mixed"] { max-width: 760px; }
.ad-row { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; width: 100%; }
.ad-cell { min-height: 50px; }

/* ---------- FAB · 패널 ---------- */
.fab-stack { position: fixed; right: 18px; bottom: 18px; display: flex; flex-direction: column; gap: 10px; z-index: 40; }
.fab {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 12px;
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--ink);
  border-radius: 999px; cursor: pointer; font-family: inherit; font-size: 13px; font-weight: 600;
}
.fab svg { width: 18px; height: 18px; }
.fab:hover { border-color: var(--accent-line); }

.side-panel {
  position: fixed; right: 18px; bottom: 84px; width: 300px; max-width: calc(100vw - 36px);
  background: var(--surface); border: 1px solid var(--line-strong); border-radius: 12px;
  z-index: 45; overflow: hidden;
}
.panel-head { display: flex; align-items: center; justify-content: space-between; padding: 13px 15px; border-bottom: 1px solid var(--line); }
.panel-head h3 { margin: 0; font-size: 15px; }
.panel-close { border: 0; background: none; color: var(--ink-3); font-size: 16px; cursor: pointer; }
.panel-body { padding: 15px; }
.set-block { margin-bottom: 16px; }
.set-block:last-child { margin-bottom: 0; }
.set-label { font-size: 12px; color: var(--ink-3); font-weight: 700; margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.04em; }
.seg { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; }
.seg .tab {
  padding: 9px 6px; border: 1px solid var(--line); background: var(--surface); color: var(--ink-2);
  border-radius: 8px; cursor: pointer; font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 12px; font-weight: 600; text-align: center;
}
.seg .tab.active { color: var(--accent-2); border-color: var(--accent-line); background: var(--accent-soft); }
.algo-seg { grid-template-columns: 1fr 1fr; margin-top: 10px; transition: opacity .15s ease; }
.algo-seg.disabled { opacity: 0.4; pointer-events: none; }
.set-inline-label { font-size: 14px; font-weight: 600; color: var(--ink); }
.set-row { display: flex; align-items: center; justify-content: space-between; padding: 6px 0; }
.row-btns { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 14px; }
.ghost-btn { padding: 9px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); border-radius: 8px; cursor: pointer; font-family: inherit; font-size: 13px; font-weight: 600; }
.ghost-btn:hover { border-color: var(--line-strong); }
.panel-backdrop { position: fixed; inset: 0; background: rgba(0,0,0,0.28); z-index: 42; }

.stats { display: flex; flex-direction: column; gap: 2px; }
.stat-row { display: grid; grid-template-columns: 1fr auto; gap: 12px; padding: 9px 4px; border-bottom: 1px solid var(--line); font-size: 14px; }
.stat-row:last-child { border-bottom: 0; }
.stat-row .d { color: var(--ink-2); font-weight: 600; }
.stat-row .n { text-align: right; font-variant-numeric: tabular-nums; font-family: 'JetBrains Mono', ui-monospace, monospace; }

/* ---------- 완료/게임오버 오버레이 ---------- */
.overlay { position: fixed; inset: 0; display: grid; place-items: center; background: rgba(0,0,0,0.42); z-index: 60; padding: 20px; }
.overlay-card { background: var(--surface); border: 1px solid var(--line-strong); border-radius: 16px; padding: 26px; width: 340px; max-width: 100%; text-align: center; }
.overlay-card .badge { display: inline-grid; place-items: center; width: 46px; height: 46px; margin: 0 auto 12px; border-radius: 50%; background: var(--accent-soft); color: var(--accent-2); font-size: 22px; font-weight: 800; }
.overlay-card h2 { margin: 0 0 4px; font-size: 22px; }
.overlay-card .big-num { font-size: 36px; font-weight: 700; color: var(--ink); margin: 6px 0; font-variant-numeric: tabular-nums; }
.overlay-card .ov-meta { color: var(--ink-2); font-size: 13px; margin-bottom: 16px; }
.btn-primary { display: inline-block; padding: 12px 20px; border: 0; border-radius: 10px; background: var(--accent); color: var(--bg); font-family: inherit; font-size: 15px; font-weight: 700; cursor: pointer; }
.ov-actions { display: flex; gap: 10px; justify-content: center; margin-top: 2px; }
.ov-actions .ghost-btn, .ov-actions .btn-primary { flex: 1; }

/* ---------- 문서 페이지 (about·전략·타일·가이드·모드) ---------- */
main { padding: 26px 0 40px; }
.doc { max-width: 760px; margin: 0 auto; }
.doc h1 { font-size: 30px; margin: 4px 0 10px; }
.doc h2 { font-size: 20px; margin: 30px 0 12px; padding-top: 8px; border-top: 1px solid var(--line); }
.doc p { margin: 0 0 14px; color: var(--ink); }
.doc ul, .doc ol { margin: 0 0 16px; padding-left: 20px; }
.doc li { margin: 6px 0; }
.lead { font-size: 17px; color: var(--ink-2); }
.muted { color: var(--ink-3); font-size: 13px; }
.breadcrumb { font-size: 13px; color: var(--ink-3); margin-bottom: 10px; }
.breadcrumb a { color: var(--ink-2); }
.breadcrumb a:hover { color: var(--accent-2); }
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; margin: 6px 0 18px; }
.card { display: block; padding: 15px; border: 1px solid var(--line); border-radius: 11px; background: var(--surface); }
.card:hover { border-color: var(--accent-line); }
.card .tag { display: inline-block; font-size: 11px; font-weight: 700; color: var(--accent-2); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 6px; }
.card h3 { margin: 0 0 5px; font-size: 16px; }
.card p { margin: 0; font-size: 13px; color: var(--ink-2); }
/* 타일 사전 카드의 미니 타일 미리보기 */
.tile-chip { display: inline-grid; place-items: center; min-width: 44px; height: 34px; padding: 0 8px; border-radius: 7px; font-family: 'JetBrains Mono', ui-monospace, monospace; font-weight: 700; font-size: 14px; margin-bottom: 8px; }
.faq details { border: 1px solid var(--line); border-radius: 10px; padding: 4px 14px; margin-bottom: 8px; background: var(--surface); }
.faq summary { padding: 11px 0; font-weight: 600; cursor: pointer; }
.faq .a { padding: 0 0 12px; color: var(--ink-2); }
.pager { display: flex; justify-content: space-between; gap: 12px; margin: 22px 0; font-size: 14px; }
.pager a { color: var(--accent-2); font-weight: 600; }
.start-link { display: inline-block; margin-top: 6px; padding: 10px 18px; border-radius: 9px; background: var(--accent); color: var(--bg); font-weight: 700; }

/* ---------- 푸터 ---------- */
.site-footer { border-top: 1px solid var(--line); background: var(--surface); margin-top: 20px; }
.site-footer.mini { position: static; }
.footer-in { padding: 26px 0 20px; }
.footer-cols { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; max-width: 760px; }
.footer-cols h4 { margin: 0 0 8px; font-size: 12px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--ink-3); }
.footer-cols a { display: block; padding: 3px 0; font-size: 14px; color: var(--ink-2); }
.footer-cols a:hover { color: var(--accent-2); }
.copyright { margin-top: 18px; padding: 14px 0 0; font-size: 12px; color: var(--ink-3); }
.site-footer.mini .copyright { margin: 0; padding: 14px 0; text-align: center; }

/* ---------- 반응형 ---------- */
@media (max-width: 720px) {
  .header-nav { display: none; }
  .footer-cols { grid-template-columns: 1fr 1fr; }
  .side-panel { right: 12px; left: 12px; width: auto; bottom: 78px; }
  .doc h1 { font-size: 25px; }
  .play-area { max-width: 460px; }
}
@media (max-width: 420px) {
  .footer-cols { grid-template-columns: 1fr; }
}