:root {
        --primary-color: #2c3e50;
        --secondary-color: #3498db;
        --accent-color: #e74c3c;
    }
    
    .khai-toan-section {
        font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        background-color: #f5f7fa;
        padding: 2rem 0;
    }
    
    .container-khai-toan {
        max-width: 1600px !important;
        margin: 0 auto;
        padding: 2rem;
        background: white;
        border-radius: 15px;
        box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    }
    
    .calculator-header {
        text-align: center;
        margin-bottom: 2rem;
        padding-bottom: 1rem;
        border-bottom: 2px solid var(--secondary-color);
    }
    
    .calculator-header h1 {
        color: var(--primary-color);
        font-weight: 700;
        margin-bottom: 0.5rem;
    }
    
    .calculator-header p {
        color: #7f8c8d;
        margin-bottom: 0;
    }
    
    .input-section {
        background: #f8f9fa;
        padding: 1.5rem;
        border-radius: 10px;
        margin-bottom: 2rem;
    }
    
    .form-label {
        font-weight: 600;
        color: var(--primary-color);
        margin-bottom: 0.5rem;
    }
    
    .form-control, .form-select {
        padding: 0.75rem 1rem;
        border-radius: 8px;
        border: 1px solid #ddd;
        transition: all 0.3s;
    }
    
    .form-control:focus, .form-select:focus {
        border-color: var(--secondary-color);
        box-shadow: 0 0 0 0.25rem rgba(52, 152, 219, 0.25);
    }
    
    .result-section {
        margin-top: 2rem;
    }
    
    .project-info {
        background: white;
        border-radius: 10px;
        padding: 1.5rem;
        margin-bottom: 2rem;
        box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    }
    
    .info-badge {
        display: inline-flex;
        align-items: center;
        background-color: var(--secondary-color);
        color: white;
        padding: 0.5rem 1rem;
        border-radius: 50px;
        font-size: 0.875rem;
        margin-right: 0.75rem;
        margin-bottom: 0.75rem;
    }
    
    .info-badge i {
        margin-right: 0.5rem;
    }
    
    .package-container {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 1.5rem;
        margin-bottom: 2rem;
    }
    
    .package-card {
        border-radius: 10px;
        overflow: hidden;
        transition: transform 0.3s;
        border: none;
        box-shadow: 0 5px 15px rgba(0,0,0,0.1);
        display: flex;
        flex-direction: column;
        height: 100%;
    }
    
    .package-header {
        padding: 1.25rem;
        color: white;
        text-align: center;
    }
    
    .package-basic .package-header {
        background: linear-gradient(135deg, #3498db, #2980b9);
    }
    
    .package-standard .package-header {
        background: linear-gradient(135deg, #2ecc71, #27ae60);
    }
    
    .package-premium .package-header {
        background: linear-gradient(135deg, #e74c3c, #c0392b);
    }
    
    .package-body {
        padding: 1.5rem;
        flex-grow: 1;
        display: flex;
        flex-direction: column;
    }
    
    .package-price {
        font-size: 1.5rem;
        font-weight: 700;
        margin: 1rem 0;
        text-align: center;
    }
    
    .price-per-m2 {
        font-size: 0.875rem;
        color: #6c757d;
        text-align: center;
        margin-bottom: 1.5rem;
    }
    
    .cost-details {
        margin-bottom: 1.5rem;
    }
    
    .cost-item {
        display: flex;
        justify-content: space-between;
        padding: 0.5rem 0;
        border-bottom: 1px solid #eee;
    }
    
    .cost-item:last-child {
        border-bottom: none;
    }
    
    .total-cost {
        font-weight: 700;
        color: var(--primary-color);
        margin-top: 1rem;
        padding-top: 1rem;
        border-top: 2px solid #eee;
    }
    
    .package-features {
        margin-top: auto;
        padding-top: 1.5rem;
    }
    
    .feature-item {
        display: flex;
        align-items: center;
        margin-bottom: 0.75rem;
    }
    
    .feature-item i {
        color: var(--secondary-color);
        margin-right: 0.75rem;
    }
    
    .notes-section {
        background: #f8f9fa;
        border-radius: 10px;
        padding: 1.5rem;
        margin-top: 2rem;
    }
    
    .notes-section ul {
        padding-left: 1.25rem;
    }
    
    .notes-section li {
        margin-bottom: 0.5rem;
    }
    
    .consult-btn {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        padding: 0.75rem 1.5rem;
        margin-top: 1rem;
    }
    
    .consult-btn i {
        margin-right: 0.5rem;
    }
    
    @media (max-width: 768px) {
        .container {
            padding: 1.5rem;
        }
        
        .package-container {
            grid-template-columns: 1fr;
        }
    }

    <style>

        .content-container h2,
        .content-container h3,
        .content-container h4 {
            color: var(--primary-color);
            margin-top: 1.5rem;
            margin-bottom: 1rem;
        }
        
        .content-container h2 {
            font-size: 1.75rem;
            border-bottom: 2px solid var(--secondary-color);
            padding-bottom: 0.5rem;
        }
        
        .content-container h3 {
            font-size: 1.5rem;
        }
        
        .content-container h4 {
            font-size: 1.25rem;
        }
        
        .content-container p {
            line-height: 1.6;
            margin-bottom: 1rem;
            color: #444;
        }
        
        .content-container ul,
        .content-container ol {
            padding-left: 1.5rem;
            margin-bottom: 1.5rem;
        }
        
        .content-container li {
            margin-bottom: 0.5rem;
            line-height: 1.6;
        }
        
        .content-container a {
            color: var(--secondary-color);
            text-decoration: none;
            transition: color 0.3s;
        }
        
        .content-container a:hover {
            color: var(--accent-color);
            text-decoration: underline;
        }
        
        .content-container img {
            max-width: 100%;
            height: auto;
            border-radius: 8px;
            margin: 1rem 0;
            box-shadow: 0 3px 10px rgba(0,0,0,0.1);
        }
        
        .content-container .highlight-box {
            background-color: #f8f9fa;
            border-left: 4px solid var(--secondary-color);
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        
        .content-container table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }
        
        .content-container table th {
            background-color: var(--primary-color);
            color: white;
            padding: 0.75rem;
            text-align: left;
        }
        
        .content-container table td {
            padding: 0.75rem;
            border-bottom: 1px solid #ddd;
        }
        
        .content-container table tr:nth-child(even) {
            background-color: #f9f9f9;
        }
        
        @media (max-width: 768px) {
            .content-container {
                padding: 1.5rem;
                margin-top: 2rem;
            }
            
            .content-container h2 {
                font-size: 1.5rem;
            }
            
            .content-container h3 {
                font-size: 1.3rem;
            }
        }