* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", "Hiragino Kaku Gothic ProN", "Meiryo", sans-serif;
  background: #eceef1;
  color: #14161a;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app-header {
  background: #14161a;
  color: #fff;
  padding: 18px 24px;
  border-bottom: 3px solid #6366f1;
}

.app-header h1 {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.06em;
}

.container {
  max-width: 560px;
  margin: 0 auto;
  padding: 24px 16px;
}

/* スコアボード */
.scoreboard {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: #d4d8de;
  border: 1px solid #d4d8de;
  margin-bottom: 16px;
}

.stat {
  background: #fff;
  padding: 14px 16px;
  text-align: center;
}

.stat-value {
  font-size: 26px;
  font-weight: 700;
  color: #14161a;
  font-variant-numeric: tabular-nums;
}

.stat-label {
  font-size: 11px;
  color: #6b7280;
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* ツールバー */
.toolbar {
  margin-bottom: 16px;
}

.btn {
  background: #fff;
  border: 1px solid #c4c9d0;
  border-radius: 0;
  padding: 10px 16px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  cursor: pointer;
  color: #14161a;
  transition: background 0.12s;
  width: 100%;
  background: #fff;
  color: #6366f1;
  border-color: #6366f1;
}

.btn:hover {
  background: #f3f4f6;
}

.btn-primary {
  background: #6366f1;
  color: #fff;
  border-color: #6366f1;
}

.btn-primary:hover {
  background: #4f46e5;
}

/* カードを並べる盤面（4×4） */
.board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

/* 1枚のカード */
.card {
  position: relative;
  aspect-ratio: 1 / 1;
  cursor: pointer;
  perspective: 600px;
}

.card-inner {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transition: transform 0.35s;
}

/* めくった状態（180度回転） */
.card.flipped .card-inner,
.card.matched .card-inner {
  transform: rotateY(180deg);
}

/* カードの表と裏の共通スタイル */
.card-front,
.card-back {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  backface-visibility: hidden;
  border: 1px solid #d4d8de;
}

/* 裏面（最初に見えている面） */
.card-front {
  background: #6366f1;
  color: #fff;
  font-size: 24px;
  border-color: #4f46e5;
}

/* 表面（絵柄。回転して見える面） */
.card-back {
  background: #fff;
  transform: rotateY(180deg);
  font-size: 36px;
}

/* そろったカード */
.card.matched .card-back {
  background: #eef2ff;
  border-color: #6366f1;
}

.card.matched {
  cursor: default;
}

/* 入力を一時的に受け付けないとき */
.board.locked .card {
  pointer-events: none;
}

/* クリア画面 */
.win-overlay {
  position: fixed;
  inset: 0;
  background: rgba(20, 22, 26, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.win-overlay[hidden] {
  display: none;
}

.win-card {
  background: #fff;
  border-top: 4px solid #6366f1;
  padding: 32px 28px;
  text-align: center;
  max-width: 320px;
  width: 100%;
}

.win-emoji {
  font-size: 48px;
}

.win-card h2 {
  font-size: 22px;
  margin: 8px 0;
  letter-spacing: 0.04em;
}

.win-card p {
  font-size: 14px;
  color: #4b5563;
  margin-bottom: 20px;
}