/* ============================================================
   슬라이드 퍼즐(15퍼즐) 전용 스타일
   - 조각은 절대 배치 + CSS 변수(--r/--c)로 위치를 잡아 transform으로
     미끄러진다. 격자 수 --n으로 조각 크기를 계산해 3~5칸을 한 판에 처리.
   - 색은 사이트 종이 톤을 따르되, 제자리에 들어간 조각만 살짝 초록빛
     신호를 준다(그림 모드에서는 신호 대신 그림이 곧 정답 안내).
   ============================================================ */

:root {
  --sp-board-bg: #d9cdb2;   /* 격자판 바탕(따뜻한 미색) */
  --sp-tile: #fdfbf6;       /* 조각 */
  --sp-tile-fixed: #e7f2e9; /* 제자리에 든 숫자 조각 */
  --sp-tile-fixed-fg: #2f9e52;
  --sp-gap: 6px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --sp-board-bg: #2a231a;
    --sp-tile: #241e17;
    --sp-tile-fixed: #1f3325;
    --sp-tile-fixed-fg: #7fd694;
  }
}
:root[data-theme="dark"] {
  --sp-board-bg: #2a231a;
  --sp-tile: #241e17;
  --sp-tile-fixed: #1f3325;
  --sp-tile-fixed-fg: #7fd694;
}

/* ---- 도입부 ---- */
.tool-intro { padding: clamp(30px, 5vw, 56px) 0 clamp(18px, 3vw, 30px); }
.tool-intro h1 { margin: 0 0 var(--space-4); }
.tool-intro .lead {
  font-size: 1.08rem;
  line-height: 1.75;
  color: var(--color-text-sub);
  max-width: 54ch;
  margin: 0;
}
.tool-intro .lead strong { color: var(--color-text); }
.tool-intro .lead-note {
  margin: var(--space-3) 0 0;
  font-size: .88rem;
  color: var(--color-text-sub);
}

/* ---- 설정 ---- */
.sp-controls {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  margin-bottom: var(--space-4);
}
.sp-field {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
}
.sp-lab {
  font-size: .95rem;
  font-weight: 700;
  color: var(--color-text-sub);
  min-width: 52px;
}
.sp-field-note {
  flex-basis: 100%;
  font-size: .84rem;
  color: var(--color-text-sub);
  padding-left: 52px;
}
.sp-privacy { font-weight: 700; color: var(--color-primary); }
.sp-chips { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.sp-chip {
  font: inherit;
  font-size: 1rem;
  cursor: pointer;
  touch-action: manipulation;
  padding: 9px 18px;
  border-radius: 999px;
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
}
.sp-chip:hover { border-color: var(--color-primary); }
.sp-chip[aria-pressed="true"] {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
  font-weight: 700;
}

/* ---- 그림 선택 ---- */
.sp-pics { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.sp-pic {
  width: 46px;
  height: 46px;
  padding: 0;
  border-radius: 10px;
  border: 2px solid var(--color-border);
  cursor: pointer;
  touch-action: manipulation;
  background-size: cover;
  background-position: center;
  overflow: hidden;
}
.sp-pic[aria-pressed="true"] {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px var(--color-primary);
}
.sp-imgtools {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.sp-upload {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
}
.sp-upload input { position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none; }
.sp-upload span {
  font-size: .95rem;
  font-weight: 700;
  padding: 8px 16px;
  border-radius: 999px;
  border: 1.5px dashed var(--color-primary);
  color: var(--color-primary);
  background: var(--color-surface);
}
.sp-upload:hover span { background: var(--color-primary-weak); }
.sp-numtoggle {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: .92rem;
  color: var(--color-text-sub);
  cursor: pointer;
}

/* ---- 상태 줄 ---- */
.sp-stage { max-width: 520px; margin: 0 auto; }
.sp-status {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}
.sp-stat {
  flex: 1;
  font-size: .95rem;
  color: var(--color-text-sub);
  font-variant-numeric: tabular-nums;
}
.sp-stat-c { text-align: center; }
.sp-stat-r { text-align: right; }
.sp-stat b { font-size: 1.3rem; color: var(--color-text); }
.sp-unit { font-size: .9rem; margin-left: 2px; color: var(--color-text-sub); }

/* ---- 게임판 ---- */
.sp-board-wrap {
  position: relative;
  display: grid;
}
.sp-board {
  --n: 4;
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  padding: var(--sp-gap);
  background: var(--sp-board-bg);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  box-shadow: var(--shadow-sm);
  touch-action: none;   /* 스와이프가 스크롤과 안 섞이도록 */
}
.sp-tile {
  position: absolute;
  top: var(--sp-gap);
  left: var(--sp-gap);
  width: calc((100% - 2 * var(--sp-gap) - (var(--n) - 1) * var(--sp-gap)) / var(--n));
  height: calc((100% - 2 * var(--sp-gap) - (var(--n) - 1) * var(--sp-gap)) / var(--n));
  transform: translate(
    calc(var(--c) * 100% + var(--c) * var(--sp-gap)),
    calc(var(--r) * 100% + var(--r) * var(--sp-gap)));
  transition: transform .13s ease;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  touch-action: none;
  -webkit-tap-highlight-color: transparent;
  -webkit-user-select: none;
  user-select: none;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  background: var(--sp-tile);
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
  font-size: clamp(.9rem, calc(34vw / var(--n)), 2.6rem);
  overflow: hidden;
}
.sp-tile:focus-visible { outline: 3px solid var(--color-text); outline-offset: 2px; z-index: 3; }
/* 제자리에 든 숫자 조각(숫자 모드에서만) */
.sp-tile.is-fixed {
  background: var(--sp-tile-fixed);
  color: var(--sp-tile-fixed-fg);
  border-color: transparent;
}
/* 밀 수 있는 조각(빈 칸과 같은 줄) 살짝 강조 */
.sp-board:not(.is-idle) .sp-tile.can-move {
  box-shadow: inset 0 0 0 2px color-mix(in srgb, var(--color-primary) 45%, transparent);
}
@supports not (background: color-mix(in srgb, red 50%, transparent)) {
  .sp-board:not(.is-idle) .sp-tile.can-move { box-shadow: inset 0 0 0 2px rgba(194,59,48,.45); }
}

/* 그림 모드 조각 */
.sp-tile.is-img {
  border-color: rgba(0,0,0,.14);
  background-image: var(--pic);
  background-repeat: no-repeat;
}
.sp-tile.is-img .sp-num {
  position: absolute;
  top: 3px;
  left: 5px;
  font-size: clamp(.7rem, calc(20vw / var(--n)), 1.1rem);
  color: #fff;
  text-shadow: 0 1px 2px rgba(0,0,0,.7);
  pointer-events: none;
}
/* 시작 전에는 조각을 살짝 죽여 둔다 */
.sp-board.is-idle .sp-tile { opacity: .55; cursor: default; }
.sp-board.is-idle .sp-tile.can-move { box-shadow: none; }
/* 완성 순간 빈 칸까지 채운 마지막 조각 */
.sp-tile.is-final { opacity: 1 !important; }

/* ---- 오버레이(시작·완성) ---- */
.sp-board-wrap > .sp-overlay,
.sp-board-wrap > .sp-board { grid-area: 1 / 1; }
.sp-overlay {
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 16px;
  z-index: 5;
  background: color-mix(in srgb, var(--color-bg) 84%, transparent);
  -webkit-backdrop-filter: blur(3px);
          backdrop-filter: blur(3px);
}
@supports not (background: color-mix(in srgb, red 50%, transparent)) {
  .sp-overlay { background: rgba(243, 240, 232, .9); }
  :root[data-theme="dark"] .sp-overlay { background: rgba(23, 19, 14, .9); }
}
.sp-overlay-panel {
  text-align: center;
  padding: var(--space-4) var(--space-5);
  max-width: 100%;
}
.sp-ov-title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
}
.sp-ov-sub { margin: 0 0 var(--space-4); font-size: .95rem; color: var(--color-text-sub); }
.sp-ov-label {
  margin: 0 0 var(--space-1);
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-primary);
}
.sp-ov-result {
  margin: 0 0 var(--space-2);
  font-size: 1.15rem;
  color: var(--color-text);
}
.sp-ov-result b { font-size: 1.5rem; color: var(--color-text); font-variant-numeric: tabular-nums; }
.sp-ov-line { margin: 0 0 var(--space-4); font-size: .95rem; color: var(--color-text-sub); }
.sp-ov-line b { color: var(--color-text); }
.sp-new { color: var(--color-primary); font-weight: 700; }

.sp-btn-big {
  font: inherit;
  font-size: 1.3rem;
  font-weight: 700;
  cursor: pointer;
  touch-action: manipulation;
  padding: 15px 40px;
  border-radius: 999px;
  border: 0;
  background: var(--color-primary);
  color: #fff;
  box-shadow: var(--shadow);
}
.sp-btn-big:hover { filter: brightness(1.06); }
.sp-btn-big:active { transform: scale(.97); }

/* ---- 아래 버튼 ---- */
.sp-actions {
  display: flex;
  justify-content: center;
  gap: var(--space-2);
  margin-top: var(--space-4);
  flex-wrap: wrap;
}
.sp-btn {
  font: inherit;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  touch-action: manipulation;
  padding: 11px 24px;
  border-radius: 999px;
  border: 1.5px solid var(--color-primary);
  background: var(--color-primary);
  color: #fff;
}
.sp-btn:hover { filter: brightness(1.06); }
.sp-btn-ghost {
  background: var(--color-surface);
  color: var(--color-primary);
}
.sp-btn-ghost:hover { background: var(--color-primary-weak); filter: none; }
.sp-btn-ghost[aria-pressed="true"] { background: var(--color-primary); color: #fff; }

/* ---- 안내 문구 ---- */
.sp-msg {
  min-height: 1.7em;
  margin: var(--space-3) 0 0;
  text-align: center;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
}

/* ---- 본문 ---- */
.prose { max-width: 720px; margin: clamp(40px, 6vw, 64px) auto 0; }
.prose h2 { margin: 0 0 var(--space-3); }
.prose p { margin: 0 0 var(--space-3); color: var(--color-text); }
.prose ul { margin: 0; padding-left: 1.2em; }
.prose li { margin-bottom: var(--space-2); }
.prose li strong { color: var(--color-text); }

@media (prefers-reduced-motion: reduce) {
  .sp-tile { transition: none; }
}

@media (max-width: 420px) {
  .sp-lab { min-width: 100%; }
  .sp-field-note { padding-left: 0; }
  .sp-stat { font-size: .86rem; }
  .sp-stat b { font-size: 1.15rem; }
}