/**
 * 15 Puzzle - スタイル定義
 * 
 * CSS変数によるテーマ管理、可変サイズ対応、モバイルファーストのレスポンシブデザイン
 */

/* カスタムプロパティ（テーマカラー） */
:root {
  --color-bg: #f8faf8;
  --color-tile: #ffffff;
  --color-accent: #6b8f71;
  --color-accent-hover: #5a7a5f;
  --color-text: #1f2421;
  --color-text-light: #4a5548;
  --color-shadow: rgba(31, 36, 33, 0.12);
  --color-shadow-strong: rgba(31, 36, 33, 0.2);
  --color-gold: #c9a227;
  
  --font-family: 'Outfit', sans-serif;
  --border-radius: 12px;
  --border-radius-sm: 8px;
  
  --tile-gap: 8px;
  --board-padding: 12px;
  --grid-size: 4;
  
  --transition-fast: 120ms ease-out;
  --transition-normal: 200ms ease-out;
}

/* リセット */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  min-height: 100dvh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 16px;
  overflow: hidden;
  touch-action: none;
  user-select: none;
}

/* コンテナ */
.container {
  width: 100%;
  max-width: 400px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ヘッダー */
.header {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* サイズ選択 */
.size-selector {
  display: flex;
  justify-content: center;
  gap: 8px;
}

.size-btn {
  padding: 8px 16px;
  border: 2px solid var(--color-accent);
  border-radius: var(--border-radius-sm);
  background: transparent;
  color: var(--color-accent);
  font-family: var(--font-family);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.size-btn:hover {
  background-color: rgba(107, 143, 113, 0.1);
}

.size-btn.active {
  background-color: var(--color-accent);
  color: white;
}

/* タイマー行 */
.timer-row {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 24px;
}

.timer {
  font-size: 2rem;
  font-weight: 600;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
}

.best-time {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--color-gold);
  font-size: 1rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.best-time .material-icons {
  font-size: 1.25rem;
}

/* ゲームエリア */
.game-area {
  display: flex;
  justify-content: center;
}

/* ボード */
.board {
  --grid-size: 4;
  display: grid;
  grid-template-columns: repeat(var(--grid-size), 1fr);
  grid-template-rows: repeat(var(--grid-size), 1fr);
  gap: var(--tile-gap);
  padding: var(--board-padding);
  background-color: var(--color-accent);
  border-radius: var(--border-radius);
  box-shadow: 0 8px 32px var(--color-shadow-strong);
  aspect-ratio: 1;
  width: min(calc(100vw - 32px), 360px);
  touch-action: none;
}

/* タイル */
.tile {
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: var(--color-tile);
  border-radius: var(--border-radius-sm);
  font-size: clamp(1rem, calc(2rem - var(--grid-size) * 0.15rem), 2rem);
  font-weight: 600;
  color: var(--color-text);
  box-shadow: 0 2px 8px var(--color-shadow);
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  will-change: transform;
}

.tile:hover {
  box-shadow: 0 4px 12px var(--color-shadow-strong);
}

.tile.empty {
  background-color: transparent;
  box-shadow: none;
  cursor: default;
}

.tile.moving {
  z-index: 10;
}

/* コントロール */
.controls {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.stats {
  font-size: 1rem;
  color: var(--color-text-light);
  font-variant-numeric: tabular-nums;
}

.buttons {
  display: flex;
  gap: 12px;
}

.btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--border-radius-sm);
  font-family: var(--font-family);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color var(--transition-normal), transform var(--transition-fast);
}

.btn:active {
  transform: scale(0.96);
}

.btn .material-icons {
  font-size: 1.25rem;
}

.btn-reset {
  background-color: var(--color-tile);
  color: var(--color-text);
  box-shadow: 0 2px 8px var(--color-shadow);
}

.btn-reset:hover {
  background-color: #f0f2f0;
}

.btn-primary {
  background-color: var(--color-accent);
  color: white;
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
}

/* モーダル */
.modal {
  position: fixed;
  inset: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: rgba(31, 36, 33, 0.5);
  backdrop-filter: blur(4px);
  z-index: 100;
  animation: fadeIn 300ms ease-out;
}

.modal[hidden] {
  display: none;
}

.modal-content {
  background-color: var(--color-tile);
  padding: 32px 48px;
  border-radius: var(--border-radius);
  box-shadow: 0 16px 64px var(--color-shadow-strong);
  text-align: center;
  animation: scaleIn 300ms ease-out;
}

.modal-content h2 {
  font-size: 1.75rem;
  color: var(--color-accent);
  margin-bottom: 16px;
}

.result-time {
  font-size: 2.5rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.result-moves {
  font-size: 1rem;
  color: var(--color-text-light);
  margin-bottom: 24px;
}

/* アニメーション */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes scaleIn {
  from { transform: scale(0.9); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

/* 完成時のパルス演出 */
.board.solved {
  animation: pulse 600ms ease-in-out;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

/* レスポンシブ */
@media (min-width: 480px) {
  .timer {
    font-size: 2.5rem;
  }
}