/* ========== Custom Minimalist & Sejuk Styling ========== */
        body.custom-buku-induk-bg {
            background: linear-gradient(135deg, #e3f2fd 0%, #b2ebf2 100%);
            min-height: 100vh;
        }
        .custom-card {
            background: rgba(255,255,255,0.97);
            border-radius: 20px;
            box-shadow: 0 4px 32px 0 rgba(38, 198, 218, 0.09), 0 1.5px 8px 0 rgba(0,0,0,0.04);
        }
        .custom-card .card-body {
            padding: 2.2rem 1.5rem;
        }
        .app-logo-wrapper {
            background: #ffffffcc;
            padding: 16px;
            border-radius: 50%;
            box-shadow: 0 2px 8px 0 rgba(38, 198, 218, 0.08);
        }
        .app-logo {
            width: 58px;
            height: 58px;
            object-fit: contain;
            filter: drop-shadow(0 1px 4px rgba(33,150,243,.08));
        }
        .custom-title {
            font-weight: 700;
            color: #0097a7;
            letter-spacing: 1px;
            margin-bottom: 4px;
        }
        .custom-alert {
            border-radius: 10px;
            font-size: 0.96rem;
            padding: 0.8rem 1.1rem;
            margin-bottom: 1.2rem;
        }
        .custom-input {
            border-radius: 14px;
            border: 1.5px solid #b2ebf2;
            padding: 0.8rem 1.1rem;
            font-size: 1.04rem;
            background: #f6fdff;
            transition: border-color .2s;
        }
        .custom-input:focus {
            border-color: #26c6da;
            box-shadow: 0 0 0 2px #b2ebf288;
        }
        .custom-btn {
            background: linear-gradient(90deg, #26c6da 0%, #1976d2 100%);
            color: #fff;
            border: none;
            border-radius: 13px;
            font-weight: 600;
            font-size: 1.05rem;
            padding: 0.85rem 0;
            box-shadow: 0 1.5px 10px 0 rgba(38, 198, 218, 0.08);
            transition: background .2s, box-shadow .2s;
        }
        .custom-btn:hover, .custom-btn:focus {
            background: linear-gradient(90deg, #1976d2 0%, #26c6da 100%);
            color: #fff;
            box-shadow: 0 3px 16px 0 rgba(38, 198, 218, 0.10);
        }
        .custom-divider {
            border-top: 1px solid #e0f7fa;
            margin: 2.1rem 0 1.1rem 0;
        }
        .custom-footer {
            color: #4dd0e1;
            font-weight: 500;
            font-size: 0.96rem;
            letter-spacing: .5px;
        }
        .animate-fadeIn {
            animation: fadeInUp 0.9s cubic-bezier(.33,.75,.6,1.0);
        }
        @keyframes fadeInUp {
            from { opacity: 0; transform: translate3d(0,32px,0);}
            to { opacity: 1; transform: translate3d(0,0,0);}
        }
        /* Responsive Tweaks */
        @media (max-width: 767px) {
            .custom-card {
                border-radius: 14px;
            }
            .custom-card .card-body {
                padding: 1.6rem 1rem;
            }
            .app-logo-wrapper {
                padding: 11px;
            }
            .app-logo {
                width: 44px;
                height: 44px;
            }
        }
        @media (max-width: 430px) {
            .custom-title {
                font-size: 1.12rem;
            }
            .custom-footer {
                font-size: 0.93rem;
            }
        }