:root {
    --card-bg-back: #90ee90; /* 黄緑 */
    --card-bg-front: #f0f0f0;
    --primary-color: #333;
    --background-color: #fafafa;
    --accent-color: #4a90e2;
}

body {
  font-family: "RocknRoll One", sans-serif;
  font-weight: 400;
  font-style: normal;
  display: flex;
    flex-direction: column;
    justify-content: flex-start; /* 上から配置 */
    align-items: center;
    min-height: 100vh;
    background-color: var(--background-color);
    color: var(--primary-color);
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

h1 {
        font-weight:bolder;
    margin-bottom: 5px;
}

.game-info {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
    font-size: 1.2em;
}

.game-container {
    perspective: 1000px;
}

.game-board {
    display: grid;
    gap: 10px;
    transition: all 0.5s;
}

.card {
    background-color: transparent;
    cursor: pointer;
    border-radius: 8px;
}

.card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.card.is-flipped .card-inner {
    transform: rotateY(180deg);
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2em;
}

.card-front {
    background-color: var(--card-bg-front);
    color: var(--primary-color);
}

.card-back {
    background-color: var(--card-bg-back);
    transform: rotateY(180deg);
}

.card.matched {
    opacity: 0.4;
    cursor: default;
}

/* --- モード別スタイル --- */

/* Normal (4x3) */
.game-board.mode-normal { grid-template-columns: repeat(4, 1fr); max-width: 500px; }
.game-board.mode-normal .card { width: 100px; height: 150px; }

/* Hard (8x5) */
.game-board.mode-hard { grid-template-columns: repeat(8, 1fr); max-width: 900px; }
.game-board.mode-hard .card { width: 90px; height: 126px; }

/* Katsumura (15x10) */
.game-board.mode-katsusumura { grid-template-columns: repeat(15, 1fr); max-width: 1400px; gap: 5px; }
.game-board.mode-katsusumura .card { width: 70px; height: 100px; border-radius: 5px; }
.game-board.mode-katsusumura .card-face { border-radius: 5px; }

/* モーダル */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
}

.modal-content {
    background: white;
    padding: 30px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

.share-buttons {
    margin: 20px 0;
    display: flex;
    justify-content: center;
    gap: 10px;
}

.share-btn, .restart-btn {
    display: inline-block;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    text-decoration: none;
    font-size: 1em;
    cursor: pointer;
    transition: background-color 0.2s;
    color: white;
}

.share-btn.copy { background-color: #777; }
.share-btn.copy:hover { background-color: #555; }

.restart-btn { background-color: var(--accent-color); }
.restart-btn:hover { background-color: #3a7bc8; }

/* レスポンシブ対応 */
@media (max-width: 920px) {
    .game-board.mode-hard { grid-template-columns: repeat(5, 1fr); max-width: 600px; }
}
@media (max-width: 640px) {
    .game-board.mode-normal { grid-template-columns: repeat(3, 1fr); max-width: 360px; }
    .game-board.mode-hard { grid-template-columns: repeat(4, 1fr); max-width: 420px; }
    .game-board.mode-katsusumura { grid-template-columns: repeat(10, 1fr); gap: 4px; }
    .game-board.mode-katsusumura .card { width: 9vw; height: 12.6vw; } /* 画面幅に追従 */
}