/* 全体スタイルと背景アニメーション */
body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    overflow: hidden;
    font-family: 'Roboto', sans-serif;
}

.background-animation {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(-45deg, #1e3c72, #2a5298, #282c34, #4b6cb7);
    background-size: 400% 400%;
    animation: gradientAnimation 10s ease infinite;
    z-index: -1;
}

@keyframes gradientAnimation {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* ヘッダー */
.header {
    text-align: center;
    color: white;
    padding: 20px;
    animation: fadeInDown 2s ease-out;
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-30px); }
    to { opacity: 1; transform: translateY(0); }
}

/* コンテンツエリア */
.main-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
    margin: 40px auto;
}

.card {
    background: rgba(255, 255, 255, 0.15);
    color: white;
    width: 250px;
    padding: 20px;
    text-align: center;
    border-radius: 10px;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    animation: zoomIn 1s ease-in-out;
}

.card:hover {
    transform: translateY(-10px) scale(1.05);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
    background: rgba(255, 255, 255, 0.3);
}

@keyframes zoomIn {
    from { transform: scale(0.8); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

/* フッター */
.footer {
    text-align: center;
    color: white;
    padding: 10px;
    margin-top: auto;
}

/* スクロールフェードイン効果 */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 1s ease, transform 1s ease;
}