/* リセット・ベース */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.7;
    color: #333;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

/* コンテナ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
}

/* ヘッダー */
header {
    text-align: center;
    margin-bottom: 50px;
    padding: 30px 0;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1a1a2e;
    letter-spacing: 0.5px;
    margin-bottom: 10px;
}

/* 注意書きボックス */
.notice-box {
    background: #fff;
    border-left: 5px solid #ffc107;
    border-radius: 8px;
    padding: 20px 24px;
    margin-bottom: 40px;
    display: flex;
    align-items: center;
    gap: 16px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.notice-icon {
    font-size: 28px;
    flex-shrink: 0;
}

.notice-content {
    font-size: 1.05rem;
    color: #333;
    line-height: 1.6;
}

.notice-content strong {
    font-weight: 700;
    color: #d97706;
}

/* スプレッドシートグリッド */
.spreadsheet-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}

/* カードスタイル */
.spreadsheet-card {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: flex;
    flex-direction: column;
}

.spreadsheet-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.12);
}

/* カードヘッダー */
.card-header {
    background: linear-gradient(135deg, #0066cc 0%, #004999 100%);
    color: #fff;
    padding: 24px;
    position: relative;
}

.card-header h2 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: 0.3px;
}

/* 更新バッジ */
.update-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    padding: 6px 14px;
    font-size: 0.875rem;
    backdrop-filter: blur(10px);
}

.update-label {
    font-weight: 500;
    opacity: 0.95;
}

.update-date {
    font-weight: 700;
    background: rgba(255, 255, 255, 0.3);
    padding: 2px 10px;
    border-radius: 12px;
}

/* カード本体 */
.card-body {
    padding: 24px;
    flex-grow: 1;
}

.card-description {
    font-size: 0.95rem;
    color: #666;
    line-height: 1.6;
}

/* カードフッター */
.card-footer {
    padding: 0 24px 24px 24px;
}

/* リンクボタン */
.btn-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    padding: 14px 24px;
    background: #0066cc;
    color: #fff;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    transition: background 0.3s ease, transform 0.2s ease;
}

.btn-link:hover {
    background: #0052a3;
    transform: translateX(3px);
}

.btn-link .arrow {
    font-size: 1.2rem;
    transition: transform 0.3s ease;
}

.btn-link:hover .arrow {
    transform: translateX(4px);
}

/* フッター */
footer {
    text-align: center;
    padding: 30px 0;
    color: #666;
    font-size: 0.9rem;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
    margin-top: 40px;
}

/* レスポンシブ */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .spreadsheet-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .notice-box {
        flex-direction: column;
        text-align: center;
    }

    .card-header h2 {
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 20px 15px;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .card-header {
        padding: 20px;
    }

    .card-body {
        padding: 20px;
    }

    .btn-link {
        font-size: 0.95rem;
        padding: 12px 20px;
    }
}