body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    color: #2b2f33;
}

/* Navbar Layout & Aesthetics */
.navbar {
    padding: 0.8rem 0;
    background-color: #ffffff !important;
    border-bottom: 1px solid #e2e8f0 !important;
}

.navbar-brand img {
    max-height: 36px;
    width: auto;
}

/* Secondary Navigation bar */
.nav-secondary {
    background-color: #ffffff !important;
    border-bottom: 1px solid #e2e8f0 !important;
}

.nav-link {
    font-size: 0.925rem;
    font-weight: 500;
    color: #4a5568 !important;
    padding: 0.5rem 0.85rem !important;
    transition: color 0.2s ease;
}

.nav-link:hover, .nav-link:focus {
    color: #0d6efd !important;
}

/* PC表示時のボタン基本スタイル (768px以上) */
@media (min-width: 768px) {
    .btn-custom-group {
        width: auto !important;
        display: inline-flex;
    }
    .btn-custom-group .btn {
        font-weight: 500;
        font-size: 0.85rem;
        border-color: #e2e8f0;
        color: #4a5568;
        padding: 0.35rem 0.85rem;
        transition: all 0.2s ease;
        white-space: nowrap;
    }
}

.btn-custom-group .btn:hover {
    background-color: #f8fafc;
    border-color: #cbd5e1;
    color: #0f172a;
}

/* スマホ表示時の設定 (767.98px以下) */
@media (max-width: 767.98px) {
    /* スマホ時のみnavbarのボーダー（下線）を非表示にする */
    .navbar {
        border-bottom: none !important;
    }

    .nav-secondary {
        border-bottom: none !important;
        padding-top: 0;
    }
    .nav-secondary .container {
        padding: 0;
    }

    /* ボタン内のテキスト（.btn-text）を非表示にしてアイコンのみにする */
    .btn-custom-group .btn-text {
        display: none !important;
    }

    /* スマホでは1列で均等に広げる */
    .btn-custom-group {
        display: flex !important;
        flex-wrap: nowrap !important;
        width: 100% !important;
    }

    .btn-custom-group .btn, 
    .btn-custom-group .btn-group {
        flex: 1 1 0% !important;
        width: 100%;
    }

    /* アイコン単体表示向けのサイズ・パディング調整 */
    .btn-custom-group .btn {
        padding: 0.5rem 0 !important;
        font-size: 1rem !important;
        text-align: center;
        justify-content: center;
        border-color: #e2e8f0;
        color: #4a5568;
    }

    .btn-custom-group .btn i {
        font-size: 1.1rem;
        margin-right: 0 !important; /* アイコン右側の余白を削除 */
    }
}

/* Dropdown Modernization */
.dropdown-menu {
    border: 1px solid rgba(0, 0, 0, 0.06);
    border-radius: 10px;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.01);
    padding: 0.5rem;
    margin-top: 8px !important;
}

.dropdown-item {
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 6px;
    padding: 0.5rem 0.85rem;
    color: #334155;
    transition: background-color 0.15s ease;
}

.dropdown-item:hover {
    background-color: #f1f5f9;
    color: #0f172a;
}

.dropdown-item-text {
    padding: 0.4rem 0.85rem 0.2rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: 0.725rem !important;
    color: #94a3b8 !important;
}

.dropdown-divider {
    border-top-color: #f1f5f9;
    margin: 0.4rem 0;
}