:root { color-scheme: dark; }

* { box-sizing: border-box; touch-action: manipulation; }

html, body {
  margin: 0; padding: 0; height: 100dvh; overflow: hidden;
  background: #0a0a0a; color: #f5f5f5;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Apple SD Gothic Neo", "Noto Sans KR", sans-serif;
  -webkit-font-smoothing: antialiased; -webkit-tap-highlight-color: transparent;
  user-select: none; -webkit-user-select: none; overscroll-behavior: none;
}

main {
  height: 100%; max-width: 480px; margin: 0 auto;
  display: flex; flex-direction: column;
  padding: max(60px, env(safe-area-inset-top)) 16px max(20px, env(safe-area-inset-bottom));
  gap: 16px;
}

/* 점수바 */
.score-bar { display: flex; gap: 8px; align-items: stretch; }
.score-box { flex: 1; background: #161616; border: 1px solid #2a2a2a; border-radius: 12px; padding: 8px 12px; text-align: center; min-width: 0; }
.score-label { display: block; font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: #a0a0a0; }
.score-val, .best-val { display: block; font-size: 22px; font-weight: 800; font-variant-numeric: tabular-nums; letter-spacing: -0.02em; color: #f5f5f5; margin-top: 2px; line-height: 1.1; }
.time-val { font-size: 22px; font-weight: 800; font-variant-numeric: tabular-nums; }
.new-btn { flex: 0 0 auto; font: inherit; color: #fff; background: #4f9eff; border: none; border-radius: 12px; padding: 0 18px; min-height: 56px; cursor: pointer; font-weight: 700; font-size: 14px; -webkit-tap-highlight-color: transparent; }
.new-btn:active { background: #3d8ae8; }
.time-unit { font-size: 13px; font-weight: 700; color: #a0a0a0; }
.score-box.low .time-val, .score-box.low .time-unit { color: #ff5d5d; }

/* 게임 영역 — N×N 타일 */
#game { flex: 1; display: flex; align-items: center; justify-content: center; min-height: 0; }
.ct {
  display: grid;
  grid-template-columns: repeat(var(--n, 5), 1fr);
  width: min(94vw, 66vh, 430px);
  aspect-ratio: 1;
  gap: 3px;
  background: #11151d;
  padding: 3px;
  border-radius: 10px;
}

/* 타일 */
.ct-cell {
  position: relative;
  margin: 0; padding: 0;
  background: #1a1f2b; border: 1px solid #262d3b; border-radius: 7px;
  cursor: pointer; -webkit-tap-highlight-color: transparent; font: inherit;
  overflow: hidden;
}
.ct-cell:active { filter: brightness(1.25); }

/* 중앙 노드 */
.node {
  position: absolute; top: 50%; left: 50%;
  width: 30%; height: 30%; transform: translate(-50%, -50%);
  border-radius: 50%;
  background: #39424f;
  transition: background 0.12s ease, box-shadow 0.12s ease;
}
/* 전선 막대 — 중앙에서 각 변까지. 기본 숨김, .show 일 때 표시 */
.w { position: absolute; background: #39424f; display: none; transition: background 0.12s ease; }
.w.show { display: block; }
.w.up    { left: 50%; top: 0;    width: 16%; height: 52%; transform: translateX(-50%); }
.w.down  { left: 50%; bottom: 0; width: 16%; height: 52%; transform: translateX(-50%); }
.w.left  { top: 50%; left: 0;    height: 16%; width: 52%; transform: translateY(-50%); }
.w.right { top: 50%; right: 0;   height: 16%; width: 52%; transform: translateY(-50%); }

/* 전원 연결됨(점등) */
.ct-cell.on { background: #16263a; border-color: #2f5e8f; }
.ct-cell.on .w { background: #4fd0ff; box-shadow: 0 0 6px rgba(79, 208, 255, 0.55); }
.ct-cell.on .node { background: #6fe0ff; box-shadow: 0 0 8px rgba(79, 208, 255, 0.7); }

/* 전원 타일 */
.ct-cell.src .node {
  width: 42%; height: 42%; border-radius: 5px;
  background: #ffce4f; box-shadow: 0 0 10px rgba(255, 206, 79, 0.7);
}
.ct-cell.src.on .node { background: #ffd95e; box-shadow: 0 0 14px rgba(255, 206, 79, 0.9); }

.ct.solved-flash .ct-cell { border-color: #46c982; }
.ct.solved-flash .ct-cell .w { background: #46e08c; box-shadow: 0 0 8px rgba(70, 224, 140, 0.7); }
.ct.solved-flash .ct-cell .node { background: #6cf0a6; }

.overlay-sub { margin: -4px 0 4px; font-size: 14px; font-weight: 600; color: #a0a0a0; }
.overlay-howto { margin: 0 0 4px; font-size: 13px; line-height: 1.45; color: #b8b8b8; }
.overlay-card .start-btn { background: #4f9eff; border-color: #4f9eff; }

/* 공통 chrome */
.home-link, .hof-link {
  position: fixed; top: max(12px, env(safe-area-inset-top)); z-index: 10;
  width: 40px; height: 40px; display: inline-flex; align-items: center; justify-content: center;
  border-radius: 999px; background: rgba(0, 0, 0, 0.35); color: #fff; text-decoration: none;
  font-size: 20px; font-weight: 600; line-height: 1; -webkit-tap-highlight-color: transparent;
  touch-action: manipulation; backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px);
  transition: background 0.15s ease; border: none; cursor: pointer; font-family: inherit;
}
.home-link { left: max(12px, env(safe-area-inset-left)); }
.hof-link { right: max(12px, env(safe-area-inset-right)); }
@media (hover: hover) { .home-link:hover, .hof-link:hover { background: rgba(0, 0, 0, 0.55); } }

/* 오버레이 */
.overlay { position: fixed; inset: 0; background: rgba(0, 0, 0, 0.55); display: flex; align-items: center; justify-content: center; z-index: 20; padding: 20px; backdrop-filter: blur(2px); -webkit-backdrop-filter: blur(2px); }
.overlay[hidden] { display: none; }
.overlay-card { background: #161616; border: 1px solid #2a2a2a; border-radius: 18px; padding: 24px 22px; display: flex; flex-direction: column; gap: 12px; align-items: center; text-align: center; min-width: 240px; max-width: 320px; width: 100%; }
.overlay-card h2 { margin: 0; font-size: 22px; font-weight: 800; letter-spacing: -0.02em; }
.overlay-score { margin: 0; font-size: 56px; font-weight: 800; font-variant-numeric: tabular-nums; letter-spacing: -0.04em; line-height: 1; }
.overlay-card button { font: inherit; color: #fff; background: rgba(255, 255, 255, 0.10); border: 1px solid rgba(255, 255, 255, 0.22); border-radius: 999px; padding: 12px 20px; min-height: 44px; cursor: pointer; font-weight: 600; font-size: 14px; width: 100%; -webkit-tap-highlight-color: transparent; }
.overlay-card button:active { background: rgba(255, 255, 255, 0.18); }
.overlay-card .save-btn { background: #4f9eff; border-color: #4f9eff; }
.overlay-card .save-btn:active { background: #3d8ae8; }