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

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

        .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;
                padding-top: 0;
            }
            .nav-secondary .container {
                padding: 0;
            }

            /* 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%;
            }

            .btn-custom-group .btn {
                padding: 0.35rem 0.25rem !important;
                font-size: 0.75rem !important;
                text-align: center;
                justify-content: center;
                border-color: #e2e8f0;
                color: #4a5568;
            }

            .btn-custom-group .btn i {
                font-size: 0.8rem;
                margin-right: 2px !important;
            }
        }

        /* 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;
        }