:root {
            --primary-dark: #0f2a3d;
            --primary-blue: #153448;
            --accent-orange: #f0a030;
            --accent-teal: #2ec4b6;
            --bg-light: #f5f7fa;
            --bg-white: #ffffff;
            --text-dark: #1a1a2e;
            --text-gray: #6b7280;
            --border-light: #e2e8f0;
            --gradient-line: linear-gradient(90deg, #7c3aed, #3b82f6, #2ec4b6);
            --selected-bg: var(--primary-dark);
            --selected-text: #ffffff;
            --card-shadow: 0 1px 3px rgba(0,0,0,0.08);
            --card-hover: 0 4px 12px rgba(0,0,0,0.12);
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
            background: var(--bg-light);
            color: var(--text-dark);
            line-height: 1.5;
        }

        /* ========== HEADER ========== */
        .header {
            background: var(--bg-white);
            padding: 20px 40px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            position: sticky;
            top: 0;
            z-index: 100;
        }

        .logo {
            display: flex;
            flex-direction: column;
            align-items: flex-start;
        }

        .logo-main {
            font-size: 36px;
            font-weight: 800;
            letter-spacing: 4px;
            color: var(--text-dark);
        }

        .logo-sub {
            font-size: 11px;
            color: var(--text-gray);
            margin-top: -4px;
        }

        .logo-sub span {
            color: var(--accent-teal);
            font-weight: 600;
        }

        .nav-links {
            display: flex;
            gap: 48px;
        }

        .nav-links a {
            text-decoration: none;
            color: var(--text-dark);
            font-size: 16px;
            font-weight: 500;
            transition: color 0.2s;
        }

        .nav-links a:hover {
            color: var(--accent-teal);
        }

        .gradient-line {
            height: 3px;
            background: var(--gradient-line);
        }

        /* ========== STEP PROGRESS ========== */
        .step-progress {
            background: var(--bg-white);
            padding: 16px 40px;
            display: flex;
            align-items: center;
            gap: 8px;
            overflow-x: auto;
            border-bottom: 1px solid var(--border-light);
        }

        .step-dot {
            width: 32px;
            height: 32px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 13px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            flex-shrink: 0;
        }

        .step-dot.active {
            background: var(--primary-dark);
            color: white;
        }

        .step-dot.completed {
            background: var(--accent-orange);
            color: white;
        }

        .step-dot.inactive {
            background: var(--border-light);
            color: var(--text-gray);
        }

        .step-connector {
            flex: 1;
            height: 2px;
            background: var(--border-light);
            min-width: 20px;
        }

        .step-connector.completed {
            background: var(--accent-orange);
        }

        /* ========== SECTION LAYOUT ========== */
        .section {
            display: none;
            min-height: calc(100vh - 120px);
        }

        .section.active {
            display: block;
        }

        .section-inner {
            max-width: 1280px;
            margin: 0 auto;
            padding: 40px;
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 48px;
            align-items: start;
        }

        .section-image {
            border-radius: 16px;
            overflow: hidden;
            position: relative;
            aspect-ratio: 4/3;
        }

        .section-image img {
            width: 100%;
            height: 100%;
            object-fit: cover;
        }

        .section-image .plus-badge {
            position: absolute;
            bottom: 20px;
            left: 50%;
            transform: translateX(-50%);
            width: 56px;
            height: 56px;
            background: var(--accent-orange);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 28px;
            color: white;
            font-weight: 700;
            box-shadow: 0 4px 12px rgba(240, 160, 48, 0.4);
        }

        .section-content {
            padding: 10px 0;
        }

        .section-title {
            font-size: 28px;
            font-weight: 700;
            margin-bottom: 24px;
            line-height: 1.3;
        }

        .section-title .highlight {
            color: var(--accent-orange);
        }

        .section-subtitle {
            font-size: 14px;
            color: var(--text-gray);
            margin-top: -16px;
            margin-bottom: 24px;
        }

        /* ========== OPTION GRID ========== */
        .option-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 12px;
            margin-bottom: 24px;
        }

        .option-grid.three-col {
            grid-template-columns: 1fr 1fr 1fr;
        }

        .option-btn {
            position: relative;
            padding: 16px 20px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            transition: all 0.2s;
            text-align: center;
            font-size: 15px;
            font-weight: 500;
            color: var(--text-dark);
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
        }

        .option-btn:hover {
            border-color: var(--primary-dark);
            box-shadow: var(--card-hover);
        }

        .option-btn.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        .option-btn .info-icon {
            position: absolute;
            right: 12px;
            top: 50%;
            transform: translateY(-50%);
            width: 20px;
            height: 20px;
            border-radius: 50%;
            border: 1.5px solid var(--border-light);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 12px;
            color: var(--text-gray);
        }

        .option-btn.selected .info-icon {
            border-color: rgba(255,255,255,0.3);
            color: rgba(255,255,255,0.7);
        }

        .option-btn .check-icon {
            width: 22px;
            height: 22px;
            background: var(--accent-orange);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 13px;
        }

        /* ========== SUB-OPTIONS ========== */
        .sub-options {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 12px;
            margin-bottom: 24px;
        }

        .sub-option {
            padding: 14px 20px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            transition: all 0.2s;
            text-align: center;
        }

        .sub-option:hover {
            border-color: var(--primary-dark);
        }

        .sub-option.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        .sub-option .sub-title {
            font-weight: 600;
            font-size: 15px;
        }

        .sub-option .sub-desc {
            font-size: 12px;
            opacity: 0.7;
            margin-top: 2px;
        }

        /* ========== INFO BOX ========== */
        .info-box {
            display: flex;
            gap: 16px;
            padding: 16px;
            background: var(--bg-light);
            border-radius: 12px;
            margin-bottom: 24px;
        }

        .info-box img {
            width: 80px;
            height: 60px;
            object-fit: cover;
            border-radius: 8px;
        }

        .info-box-placeholder {
            width: 80px;
            height: 60px;
            background: #ddd;
            border-radius: 8px;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
        }

        .info-box p {
            font-size: 13px;
            color: var(--text-gray);
            line-height: 1.6;
        }

        /* ========== PRODUCT CARD (Panels) ========== */
        .panel-option {
            padding: 16px 20px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            transition: all 0.2s;
            margin-bottom: 10px;
            display: flex;
            align-items: center;
            justify-content: space-between;
        }

        .panel-option:hover {
            border-color: var(--primary-dark);
        }

        .panel-option.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        .panel-option .panel-name {
            font-weight: 600;
            font-size: 15px;
        }

        .panel-option .panel-specs {
            font-size: 12px;
            opacity: 0.6;
            margin-top: 2px;
        }

        .panel-option .panel-info {
            width: 22px;
            height: 22px;
            border-radius: 50%;
            border: 1.5px solid var(--border-light);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 12px;
            color: var(--text-gray);
            flex-shrink: 0;
        }

        .panel-option.selected .panel-info {
            border-color: rgba(255,255,255,0.3);
            color: rgba(255,255,255,0.7);
        }

        /* ========== QUANTITY SELECTOR ========== */
        .quantity-row {
            display: flex;
            gap: 12px;
            margin: 24px 0;
        }

        .qty-btn {
            width: 64px;
            height: 56px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            font-size: 18px;
            font-weight: 600;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 6px;
            transition: all 0.2s;
        }

        .qty-btn:hover {
            border-color: var(--primary-dark);
        }

        .qty-btn.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        /* ========== PRICE BAR ========== */
        .price-bar {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 20px 0;
            border-top: 1px solid var(--border-light);
            margin-top: 12px;
        }

        .price-bar .product-name {
            font-weight: 700;
            font-size: 16px;
        }

        .price-bar .product-tax {
            font-size: 12px;
            color: var(--text-gray);
        }

        .price-bar .price {
            font-size: 32px;
            font-weight: 800;
        }

        /* ========== STORAGE CARD ========== */
        .storage-card {
            border: 2px solid var(--border-light);
            border-radius: 16px;
            overflow: hidden;
            cursor: pointer;
            transition: all 0.2s;
            margin-bottom: 16px;
        }

        .storage-card:hover {
            box-shadow: var(--card-hover);
        }

        .storage-card.selected {
            border-color: var(--primary-dark);
        }

        .storage-card-inner {
            padding: 20px;
            background: var(--bg-white);
            display: flex;
            gap: 16px;
        }

        .storage-card.selected .storage-card-inner {
            background: var(--primary-dark);
            color: white;
        }

        .storage-img-placeholder {
            width: 100px;
            height: 80px;
            background: #374151;
            border-radius: 8px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 10px;
            text-align: center;
            flex-shrink: 0;
        }

        .storage-card .storage-details {
            flex: 1;
        }

        .storage-card .storage-name {
            font-weight: 700;
            font-size: 16px;
            display: flex;
            align-items: center;
            justify-content: space-between;
        }

        .storage-card .storage-specs {
            font-size: 13px;
            opacity: 0.8;
            margin-top: 6px;
        }

        .storage-card .storage-specs li {
            margin-bottom: 2px;
        }

        .storage-card .storage-footer {
            display: flex;
            align-items: center;
            justify-content: space-between;
            margin-top: 10px;
        }

        .storage-badge {
            display: inline-flex;
            align-items: center;
            gap: 4px;
            padding: 4px 10px;
            border-radius: 20px;
            font-size: 12px;
            font-weight: 600;
        }

        .storage-card.selected .storage-badge {
            background: rgba(255,255,255,0.15);
            color: white;
        }

        .storage-card:not(.selected) .storage-badge {
            background: var(--bg-light);
            color: var(--text-dark);
        }

        .storage-price {
            font-size: 18px;
            font-weight: 700;
        }

        /* ========== CABLE SECTION ========== */
        .cable-group {
            margin-bottom: 28px;
        }

        .cable-group h3 {
            font-size: 17px;
            font-weight: 700;
            margin-bottom: 4px;
        }

        .cable-group .cable-desc {
            font-size: 13px;
            color: var(--text-gray);
            margin-bottom: 14px;
        }

        .cable-options {
            display: flex;
            gap: 10px;
            flex-wrap: wrap;
        }

        .cable-btn {
            min-width: 64px;
            padding: 14px 20px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            text-align: center;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.2s;
        }

        .cable-btn:hover {
            border-color: var(--primary-dark);
        }

        .cable-btn.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        .cable-ohne {
            width: 100%;
            padding: 14px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            background: var(--bg-white);
            cursor: pointer;
            text-align: center;
            font-size: 15px;
            font-weight: 500;
            transition: all 0.2s;
            margin-top: 10px;
        }

        .cable-ohne:hover {
            border-color: var(--primary-dark);
        }

        /* ========== ETAGEN (Building Floors) ========== */
        .etagen-grid {
            display: grid;
            grid-template-columns: 1fr 1fr 1fr;
            gap: 14px;
            margin-bottom: 24px;
        }

        .etage-card {
            padding: 20px 16px;
            border: 2px solid var(--border-light);
            border-radius: 14px;
            background: var(--bg-white);
            cursor: pointer;
            text-align: center;
            transition: all 0.2s;
        }

        .etage-card:hover {
            border-color: var(--primary-dark);
            box-shadow: var(--card-hover);
        }

        .etage-card.selected {
            background: var(--primary-dark);
            color: white;
            border-color: var(--primary-dark);
        }

        .etage-icon {
            font-size: 40px;
            margin-bottom: 8px;
        }

        .etage-card .etage-label {
            font-size: 13px;
            font-weight: 500;
        }

        /* ========== SUMMARY ========== */
        .summary-card {
            background: var(--bg-white);
            border-radius: 16px;
            padding: 28px;
            border: 2px solid var(--border-light);
        }

        .summary-card h3 {
            font-size: 20px;
            font-weight: 700;
            margin-bottom: 20px;
        }

        .summary-line {
            display: flex;
            justify-content: space-between;
            padding: 10px 0;
            border-bottom: 1px solid var(--border-light);
            font-size: 14px;
        }

        .summary-line .label {
            color: var(--text-gray);
        }

        .summary-line .value {
            font-weight: 600;
        }

        .summary-total {
            display: flex;
            justify-content: space-between;
            padding: 16px 0 0;
            font-size: 20px;
            font-weight: 800;
        }

        .summary-note {
            font-size: 12px;
            color: var(--text-gray);
            margin-top: 4px;
            text-align: right;
        }

        /* ========== DATE PICKER ========== */
        .date-section {
            margin-top: 24px;
        }

        .date-section label {
            font-weight: 600;
            font-size: 14px;
            display: block;
            margin-bottom: 8px;
        }

        .date-input {
            width: 100%;
            padding: 14px 16px;
            border: 2px solid var(--border-light);
            border-radius: 12px;
            font-size: 15px;
            font-family: inherit;
            outline: none;
            transition: border-color 0.2s;
        }

        .date-input:focus {
            border-color: var(--primary-dark);
        }

        /* ========== BUTTONS ========== */
        .btn-row {
            display: flex;
            gap: 12px;
            margin-top: 32px;
        }

        .btn-primary {
            flex: 1;
            padding: 16px 32px;
            background: var(--primary-dark);
            color: white;
            border: none;
            border-radius: 12px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            font-family: inherit;
        }

        .btn-primary:hover {
            background: #1a3a52;
            box-shadow: var(--card-hover);
        }

        .btn-secondary {
            padding: 16px 32px;
            background: transparent;
            color: var(--text-dark);
            border: 2px solid var(--border-light);
            border-radius: 12px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            font-family: inherit;
        }

        .btn-secondary:hover {
            border-color: var(--primary-dark);
        }

        .btn-submit {
            flex: 1;
            padding: 16px 32px;
            background: #16a34a;
            color: white;
            border: none;
            border-radius: 12px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            font-family: inherit;
        }

        .btn-submit:hover {
            background: #15803d;
        }

        /* ========== BOTTOM NAV ========== */
        .bottom-nav {
            position: fixed;
            bottom: 0;
            left: 0;
            right: 0;
            background: var(--bg-white);
            border-top: 1px solid var(--border-light);
            padding: 12px 40px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            z-index: 100;
        }

        .bottom-nav-left {
            display: flex;
            align-items: center;
            gap: 24px;
        }

        .bottom-nav-icon {
            font-size: 22px;
            cursor: pointer;
            color: var(--text-gray);
            transition: color 0.2s;
        }

        .bottom-nav-icon:hover {
            color: var(--text-dark);
        }

        .bottom-nav-link {
            font-weight: 600;
            font-size: 15px;
            color: var(--text-dark);
            text-decoration: none;
        }

        .bottom-nav-right {
            display: flex;
            align-items: center;
            gap: 16px;
        }

        .bottom-price-tag {
            font-size: 20px;
            font-weight: 800;
        }

        /* ========== PLACEHOLDER IMAGES ========== */
        .img-placeholder {
            width: 100%;
            height: 100%;
            background: linear-gradient(135deg, #2d5016 0%, #4a7c23 30%, #1a3a1a 60%, #3d6b3d 100%);
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            color: rgba(255,255,255,0.6);
            font-size: 14px;
            position: relative;
            overflow: hidden;
        }

        .img-placeholder::before {
            content: '';
            position: absolute;
            top: 10%;
            right: 10%;
            width: 30%;
            height: 40%;
            background: rgba(74, 124, 35, 0.5);
            transform: skewY(-5deg);
            border-radius: 4px;
        }

        .img-placeholder::after {
            content: '🏠 ☀️';
            font-size: 48px;
            z-index: 1;
        }

        /* ========== RESPONSIVE ========== */
        @media (max-width: 768px) {
            .section-inner {
                grid-template-columns: 1fr;
                padding: 20px;
                gap: 24px;
            }

            .header {
                padding: 16px 20px;
            }

            .nav-links {
                gap: 24px;
                font-size: 14px;
            }

            .section-title {
                font-size: 22px;
            }

            .option-grid.three-col {
                grid-template-columns: 1fr 1fr;
            }

            .etagen-grid {
                grid-template-columns: 1fr;
            }

            .cable-options {
                flex-wrap: wrap;
            }

            .bottom-nav {
                padding: 10px 20px;
            }
        }

        /* padding for bottom nav */
        .section {
            padding-bottom: 80px;
        }