.form-section {
            background-color: #f8f9fa;
            border-radius: 10px;
            padding: 25px;
            margin-bottom: 25px;
            box-shadow: 0 0 15px rgba(0,0,0,0.1);
            display: none;
        }
        .form-section.active {
            display: block;
        }
        .section-title {
            color: #0d6efd;
            border-bottom: 2px solid #0d6efd;
            padding-bottom: 10px;
            margin-bottom: 20px;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        .required-field::after {
            content: " *";
            color: red;
        }
        .step-indicator {
            display: flex;
            justify-content: space-between;
            margin-bottom: 30px;
            position: relative;
        }
        .step-indicator::before {
            content: '';
            position: absolute;
            top: 25px;
            left: 0;
            right: 0;
            height: 3px;
            background-color: #e9ecef;
            z-index: 1;
        }
        .step {
            display: flex;
            flex-direction: column;
            align-items: center;
            position: relative;
            z-index: 2;
            cursor: pointer;
            flex: 1;
        }
        .step-icon {
            width: 50px;
            height: 50px;
            border-radius: 50%;
            background-color: #e9ecef;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 8px;
            font-size: 1.2rem;
            color: #6c757d;
            transition: all 0.3s ease;
        }
        .step.active .step-icon {
            background-color: #0d6efd;
            color: white;
        }
        .step.completed .step-icon {
            background-color: #198754;
            color: white;
        }
        .step-label {
            font-size: 0.85rem;
            text-align: center;
            color: #6c757d;
            font-weight: 500;
        }
        .step.active .step-label {
            color: #0d6efd;
            font-weight: 600;
        }
        .step.completed .step-label {
            color: #198754;
        }
        .navigation-buttons {
            display: flex;
            justify-content: space-between;
            margin-top: 25px;
        }
        .material-section {
            background-color: #e9ecef;
            border-radius: 8px;
            padding: 15px;
            margin-bottom: 15px;
        }
        .door-window-section {
            background-color: #e9ecef;
            border-radius: 8px;
            padding: 15px;
            margin-bottom: 15px;
            border: 1px solid #ffeaa7;
        }
        .add-btn {
            margin-top: 10px;
        }
        .door-window-item {
            border-bottom: 1px dashed #dee2e6;
            padding-bottom: 15px;
            margin-bottom: 15px;
        }
        .door-window-item:last-child {
            border-bottom: none;
            margin-bottom: 0;
        }
        .remove-btn {
            margin-top: 25px;
        }
        .area-display {
            background-color: #d1edff;
            border-radius: 8px;
            padding: 15px;
            margin-top: 15px;
            border-left: 4px solid #0d6efd;
        }
        .area-value {
            font-weight: bold;
            color: #198754;
            font-size: 1.1em;
        }
        .calculated-area {
            background-color: #e7f7ef;
            border-radius: 6px;
            padding: 10px;
            margin-top: 10px;
            border-left: 3px solid #198754;
        }
        .layer-table {
            margin-top: 15px;
            display: none;
        }
        .layer-row {
            border-bottom: 1px solid #dee2e6;
            padding: 8px 0;
        }
        .layer-row:last-child {
            border-bottom: none;
        }
        .material-modal .modal-body {
            max-height: 400px;
            overflow-y: auto;
        }
        .material-item {
            padding: 10px;
            border-bottom: 1px solid #eee;
            cursor: pointer;
        }
        .material-item:hover {
            background-color: #f8f9fa;
        }
        .material-item.selected {
            background-color: #e3f2fd;
            border-left: 4px solid #0d6efd;
        }
        .total-thickness {
            font-weight: bold;
            color: #198754;
            margin-top: 10px;
        }
        .material-input-group {
            display: flex;
            gap: 10px;
        }
        .material-input-group input {
            flex: 1;
        }
        .counter-input {
            display: flex;
            align-items: center;
        }
        .counter-btn {
            width: 40px;
            height: 40px;
            border: 1px solid #ced4da;
            background-color: #f8f9fa;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
        }
        .counter-btn:hover {
            background-color: #e9ecef;
        }
        .counter-value {
            width: 60px;
            text-align: center;
            border: 1px solid #ced4da;
            border-left: none;
            border-right: none;
            height: 40px;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .resistance-display {
            background-color: #fff3cd;
            border-radius: 6px;
            padding: 10px;
            margin-top: 10px;
            border-left: 3px solid #ffc107;
        }
        .volume-display {
            background-color: #e7f7ef;
            border-radius: 8px;
            padding: 15px;
            margin-top: 15px;
            border-left: 4px solid #198754;
        }
        .result-box {
            background-color: #f8f9fa;
            border-radius: 8px;
            padding: 15px;
            margin-bottom: 15px;
            border-left: 4px solid #0d6efd;
        }
        .q-value {
            font-size: 1.2em;
            font-weight: bold;
            color: #198754;
        }
        .r-subscript {
            font-size: 0.8em;
            vertical-align: sub;
        }
        .q-ha {
            background-color: #e7f7ef;
            border-radius: 8px;
            padding: 15px;
            margin-top: 15px;
            border-left: 4px solid #198754;
        }
        .heater-type {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border-radius: 8px;
            padding: 15px;
            margin-bottom: 15px;
        }
        .heater-type h6 {
            color: white;
            margin-bottom: 10px;
        }
        .heater-count {
            font-size: 1.3em;
            font-weight: bold;
            color: #fff3cd;
        }
        .alert-warning {
            font-size: 0.85em;
            padding: 10px;
            border-radius: 5px;
            margin-top: 10px;
        }
        #logo {
            display: flex;
            align-items: center;
            gap: 15px;
            padding: 12px 20px;
            border-radius: 12px;
            box-shadow: 0 4px 15px rgba(0,0,0,0.15);
            max-width: 500px;
            margin: 10px auto;
        }
        #logo a {
            display: flex;
            align-items: center;
            gap: 15px;
            text-decoration: none;
            color: inherit;
            width: 100%;
        }
        .logo-main {
            width: 50px;
            height: 50px;
            padding: 6px;
            background: white;
            border-radius: 50%;
            box-shadow: 0 2px 8px rgba(0,0,0,0.25);
            flex-shrink: 0;
        }
        #logo h6 {
            color: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
            font-size: 13px;
            font-weight: 600;
            line-height: 1.3;
            margin: 0;
            text-align: left;
            flex: 1;
        }
        @media (max-width: 768px) {
            #logo {
                padding: 10px 15px;
                max-width: 90%;
            }
            .logo-main {
                width: 45px;
                height: 45px;
            }
            #logo h6 {
                font-size: 12px;
                line-height: 1.2;
            }
        }