:root {
            --primary-color: #667eea;
            --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #e9ecef 100%);
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            background: var(--bg-gradient);
            min-height: 100vh;
        }

        /* Header */
        .navbar {
            background: white;
            box-shadow: 0 2px 10px rgba(0,0,0,0.08);
        }

        .navbar-brand {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--primary-color) !important;
        }

        .nav-link {
            color: #4a5568 !important;
            font-weight: 500;
            transition: color 0.3s;
        }

        .nav-link:hover {
            color: var(--primary-color) !important;
        }

        /* Hero Section */
        .hero-section {
            padding: 4rem 0;
            text-align: center;
        }

        .hero-section h1 {
            font-size: 2rem;
            color: #1a202c;
            font-weight: 500;
            margin-bottom: 1rem;
        }

        .hero-section p {
            font-size: 1.3rem;
            color: #718096;
            margin-bottom: 2rem;
        }

        .btn-primary-custom {
            background: var(--primary-gradient);
            color: white;
            padding: 0.9rem 2rem;
            border-radius: 50px;
            font-weight: 600;
            border: none;
            transition: all 0.3s;
            text-decoration: none;
            display: inline-block;
        }

        .btn-primary-custom:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 25px rgba(102, 126, 234, 0.3);
            color: white;
        }

        .btn-secondary-custom {
            background: white;
            color: var(--primary-color);
            padding: 0.9rem 2rem;
            border-radius: 50px;
            font-weight: 600;
            border: 2px solid var(--primary-color);
            transition: all 0.3s;
            text-decoration: none;
            display: inline-block;
        }

        .btn-secondary-custom:hover {
            background: var(--primary-color);
            color: white;
        }

        /* Categories Section */
        .categories-section {
            padding: 3rem 0;
        }

        .section-title {
            text-align: center;
            font-size: 2rem;
            color: #1a202c;
            margin-bottom: 1rem;
            font-weight: 500;
        }

        .section-subtitle {
            text-align: center;
            font-size: 1.1rem;
            color: #718096;
            margin-bottom: 3rem;
        }

        .category-card {
            background: white;
            padding: 2rem;
            border-radius: 20px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.06);
            transition: all 0.3s;
            height: 100%;
            text-decoration: none;
            color: inherit;
            display: block;
        }

        .category-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 40px rgba(0,0,0,0.12);
            text-decoration: none;
            color: inherit;
        }

        .category-icon {
            font-size: 2.5rem;
            margin-bottom: 1rem;
        }

        .category-card h3 {
            font-size: 1.4rem;
            color: #2d3748;
            margin-bottom: 0.8rem;
        }

        .category-card p {
            color: #718096;
            font-size: 1rem;
            margin-bottom: 0;
        }

        /* Advanced Section */
        .advanced-section {
            padding: 3rem 0;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            margin: 4rem 0;
        }

        .advanced-section .section-title {
            color: white;
        }

        .advanced-section .section-subtitle {
            color: rgba(255, 255, 255, 0.9);
        }

        .advanced-card {
            background: white;
            padding: 2rem;
            border-radius: 20px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.15);
            transition: all 0.3s;
            height: 100%;
        }

        .advanced-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 40px rgba(0,0,0,0.25);
        }

        .advanced-badge {
            display: inline-block;
            background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
            color: white;
            padding: 0.3rem 1rem;
            border-radius: 20px;
            font-size: 0.85rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }

        /* Stats Section */
        .stats-section {
            padding: 3rem 2rem;
            background: white;
            border-radius: 20px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.06);
            margin: 4rem 0;
        }

        .stat-item {
            text-align: center;
        }

        .stat-item h3 {
            font-size: 2.5rem;
            color: var(--primary-color);
            font-weight: 800;
            margin-bottom: 0.5rem;
        }

        .stat-item p {
            color: #718096;
            font-size: 1.1rem;
            margin-bottom: 0;
        }

        /* Features Section */
        .features-section {
            padding: 5rem 0;
        }

        .feature-item {
            text-align: center;
            padding: 2rem;
        }

        .feature-icon {
            width: 80px;
            height: 80px;
            background: #667eea;
            border-radius: 20px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 1.5rem;
            font-size: 2rem;
        }

        .feature-item h4 {
            font-size: 1.3rem;
            color: #2d3748;
            margin-bottom: 1rem;
        }

        .feature-item p {
            color: #718096;
            margin-bottom: 0;
        }

        /* Footer */
        footer {
            background: #2d3748;
            color: #e2e8f0;
            padding: 3rem 0 2rem;
            margin-top: 5rem;
        }

        .footer-section h4 {
            color: white;
            margin-bottom: 1rem;
            font-size: 1.2rem;
        }

        .footer-section ul {
            list-style: none;
            padding: 0;
        }

        .footer-section ul li {
            margin-bottom: 0.7rem;
        }

        .footer-section a {
            color: #cbd5e0;
            text-decoration: none;
            transition: color 0.3s;
        }

        .footer-section a:hover {
            color: var(--primary-color);
        }

        .footer-bottom {
            text-align: center;
            margin-top: 3rem;
            padding-top: 2rem;
            border-top: 1px solid #4a5568;
            color: #cbd5e0;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .hero-section h1 {
                font-size: 2rem;
            }

            .hero-section p {
                font-size: 1.1rem;
            }
        }
        
        .hero
 {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url(data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="2" fill="rgba(255,255,255,0.1)"/></svg>);
    opacity: 0.3;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

/* -- */

.content-area {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 30px;
    min-height: 80vh;
}

.sidebar {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
    padding: 0;
    max-height: 80vh;
    overflow-y: auto;
}

.sidebar-header {
    background: linear-gradient(180deg, #edb056 0%, #e9b76c 42%);
    color: white;
    padding: 20px;
    border-radius: 15px 15px 0 0;
    text-align: center;
}

 .test-item {
            padding: 15px 30px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    margin: 11px 5px;
    border-radius: 10px;
			background: linear-gradient(135deg, #f5f6f8 0%, #eaeaea 100%);
        }

        .test-item:hover {
            background: rgba(102, 126, 234, 0.1);
            transform: translateX(5px);
        }

        .test-item.active {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
        }

        .test-item:last-child {
            border-bottom: none;
            border-radius: 0 0 15px 15px;
        }

        .test-title {
            font-weight: 600;
            margin-bottom: 5px;
        }

        .test-info {
            font-size: 0.85em;
            opacity: 0.7;
        }

        .test-status {
            position: absolute;
            right: 20px;
            top: 50%;
            transform: translateY(-50%);
        }

        .status-badge {
            padding: 5px 8px;
    border-radius: 5px;
    font-size: 0.75em;
    font-weight: 600;
        }

        .status-new {
           background: #2892a0;
    color: #fffafa;
        }

        .status-completed {
            background: #e8f5e8;
            color: #2e7d32;
        }

        .status-in-progress {
            background: #fff3e0;
            color: #f57c00;
        }

        .welcome-message {
            text-align: center;
            color: #666;
            margin-top: 50px;
        }

        .question-card {
            background: #f8f9fa;   
            /*border-radius: 10px;*/
            padding: 20px;
            margin-bottom: 20px;
            border-left: 4px solid #667eea;  
        }

        .option-item {
            padding: 10px 15px;
            margin: 10px 0;
            border: 2px solid #e9ecef;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .option-item:hover {
            border-color: #667eea;
            background: rgba(102, 126, 234, 0.05);
        }

        .option-item.selected {
            border-color: #667eea;
            background: rgba(102, 126, 234, 0.1);
        }

        .test-header {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 20px;
            border-radius: 10px;
            margin-bottom: 30px;
        }

        .progress-info {
            display: flex;
            justify-content: space-between;
            margin-bottom: 20px;
        }

        .btn-primary {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border: none;
            border-radius: 25px;
            padding: 10px 30px;
            font-weight: 600;
            transition: all 0.3s ease;
        }

        .btn-primary:hover {
            transform: translateY(-2px);
            box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
        }

        .question-result {
            background: #f8f9fa;
            transition: all 0.3s ease;
        }

        .question-result:hover {
            background: #e9ecef;
            transform: translateX(5px);
        }

        .results-container {
            border: 1px solid #e9ecef;
            border-radius: 10px;
            padding: 15px;
            background: white;
        }

        .results-container::-webkit-scrollbar {
            width: 8px;
        }

        .results-container::-webkit-scrollbar-track {
            background: #f1f1f1;
            border-radius: 4px;
        }

        .results-container::-webkit-scrollbar-thumb {
            background: #888;
            border-radius: 4px;
        }

        .results-container::-webkit-scrollbar-thumb:hover {
            background: #555;
        }

        @media (max-width: 768px) {
            .sidebar {
                margin-bottom: 20px;
                max-height: 300px;
            }
        }
        
        .badge-warning {color: red;}
         .badge-danger {color: red;}
          .badge-success {color: #198754;}
          
          math {font-size: 20px;}
          
          
    .faq{
    max-width: 1000px;
    margin: 3rem auto;
    padding: 0 1rem;
  }
  .faq__title{
    margin: 0 0 .5rem;
    /*font-size: 1.8rem;*/
    line-height: 1.2;
    text-align: center;
  }
  .faq__desc{
    margin: 0 0 1.2rem;
    text-align: center;
    color: #6b7280;
  }
  .faq__list{
    display: grid;
    gap: 12px;
  }
  .faq__item{
    background: #fff;
    border: 1px solid rgba(0,0,0,.08);
    border-radius: 14px;
    box-shadow: 0 10px 28px rgba(0,0,0,.06);
    overflow: hidden;
  }
  .faq__question{
    cursor: pointer;
    list-style: none;
    padding: 14px 16px;
    font-weight: 700;
    position: relative;
    padding-right: 42px;
  }
  .faq__question::-webkit-details-marker{ display: none; }
  .faq__question::after{
    content: "▾";
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    transition: transform .15s ease;
    opacity: .75;
  }
  .faq__item[open] .faq__question::after{
    transform: translateY(-50%) rotate(180deg);
  }
  .faq__answer{
    padding: 0 16px 14px;
    color: #374151;
  }
  .faq__answer p{ margin: 10px 0; }
  .faq__answer ul{ margin: 10px 0 0; padding-left: 18px; }
  .faq__answer li{ margin: 6px 0; }
  .faq__note{
    margin: 12px 0 0;
    color: #6b7280;
    font-size: .95rem;
  }