* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background: linear-gradient(135deg, #f5f7fa 0%, #e4e7f1 100%);
            color: #333;
            line-height: 1.6;
            padding: 20px;
            min-height: 100vh;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
        }
        
        header {
            text-align: center;
            padding: 30px 0;
            background: linear-gradient(135deg, #1a5276, #3498db);
            color: white;
            border-radius: 15px;
            margin-bottom: 25px;
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
            position: relative;
            overflow: hidden;
        }
        
        header::before {
            content: "";
            position: absolute;
            top: -50%;
            left: -50%;
            width: 200%;
            height: 200%;
            background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0) 70%);
            transform: rotate(30deg);
        }
        
        header h1 {
            font-size: 2.8rem;
            margin-bottom: 10px;
            text-shadow: 0 2px 4px rgba(0,0,0,0.2);
            position: relative;
        }
        
        header p {
            font-size: 1.3rem;
            opacity: 0.9;
            max-width: 700px;
            margin: 0 auto;
            position: relative;
        }
        
        .upload-section {
            background: white;
            border-radius: 15px;
            padding: 30px;
            margin-bottom: 30px;
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
            text-align: center;
            border: 3px dashed #3498db;
            transition: all 0.3s ease;
        }
        
        .upload-section:hover {
            transform: translateY(-5px);
            box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
            border-color: #2ecc71;
        }
        
        .upload-icon {
            font-size: 4rem;
            color: #3498db;
            margin-bottom: 20px;
        }
        
        .upload-title {
            font-size: 1.8rem;
            margin-bottom: 15px;
            color: #2c3e50;
        }
        
        .upload-desc {
            color: #7f8c8d;
            margin-bottom: 25px;
            font-size: 1.1rem;
            max-width: 700px;
            margin-left: auto;
            margin-right: auto;
        }
        
        .file-input-wrapper {
            position: relative;
            display: inline-block;
            margin-bottom: 20px;
        }
        
        .file-input-wrapper input[type="file"] {
            position: absolute;
            left: 0;
            top: 0;
            opacity: 0;
            width: 100%;
            height: 100%;
            cursor: pointer;
        }
        
        .file-input-label {
            display: inline-block;
            padding: 15px 40px;
            background: linear-gradient(135deg, #3498db, #2980b9);
            color: white;
            border-radius: 50px;
            font-size: 1.2rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: 0 6px 15px rgba(52, 152, 219, 0.4);
        }
        
        .file-input-label:hover {
            background: linear-gradient(135deg, #2980b9, #1a5276);
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(52, 152, 219, 0.6);
        }
        
        .file-name {
            margin-top: 15px;
            font-size: 1rem;
            color: #3498db;
            font-weight: 500;
        }
        
        .controls {
            display: flex;
            justify-content: space-between;
            margin-bottom: 25px;
            flex-wrap: wrap;
            gap: 15px;
        }
        
        .btn {
            padding: 14px 30px;
            background: linear-gradient(135deg, #2ecc71, #27ae60);
            color: white;
            border: none;
            border-radius: 50px;
            cursor: pointer;
            font-size: 1.1rem;
            font-weight: 600;
            transition: all 0.3s ease;
            display: inline-flex;
            align-items: center;
            gap: 10px;
            box-shadow: 0 6px 15px rgba(46, 204, 113, 0.4);
        }
        
        .btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(46, 204, 113, 0.6);
        }
        
        .btn-download {
            background: linear-gradient(135deg, #e74c3c, #c0392b);
            box-shadow: 0 6px 15px rgba(231, 76, 60, 0.4);
        }
        
        .btn-download:hover {
            box-shadow: 0 8px 20px rgba(231, 76, 60, 0.6);
        }
        
        .btn-upload {
            background: linear-gradient(135deg, #3498db, #2980b9);
            box-shadow: 0 6px 15px rgba(52, 152, 219, 0.4);
        }
        
        .dashboard {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 30px;
            margin-bottom: 35px;
        }
        
        .card {
            background: white;
            border-radius: 15px;
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.08);
            padding: 25px;
            transition: transform 0.4s ease, box-shadow 0.4s ease;
            overflow: hidden;
            position: relative;
        }
        
        .card::before {
            content: "";
            position: absolute;
            top: 0;
            left: 0;
            width: 5px;
            height: 100%;
            background: linear-gradient(to bottom, #3498db, #2ecc71);
        }
        
        .card:hover {
            transform: translateY(-8px);
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.15);
        }
        
        .card-header {
            padding-bottom: 18px;
            margin-bottom: 18px;
            border-bottom: 2px solid #f1f2f6;
            display: flex;
            align-items: center;
            gap: 15px;
        }
        
        .card-header h2 {
            font-size: 1.6rem;
            color: #2c3e50;
            font-weight: 700;
        }
        
        .card-header i {
            font-size: 1.8rem;
            color: #3498db;
        }
        
        .card-content {
            min-height: 250px;
        }
        
        .table-container {
            overflow-x: auto;
            margin-bottom: 25px;
            border-radius: 10px;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
        }
        
        table {
            width: 100%;
            border-collapse: separate;
            border-spacing: 0;
            margin: 20px 0;
            font-size: 1rem;
            border-radius: 10px;
            overflow: hidden;
        }
        
        th {
            background: linear-gradient(to bottom, #3498db, #2980b9);
            color: white;
            text-align: left;
            padding: 16px;
            font-weight: 600;
            cursor: pointer;
            position: relative;
        }
        
        th:hover {
            background: linear-gradient(to bottom, #2980b9, #1a5276);
        }
        
        th::after {
            content: '↕';
            position: absolute;
            right: 15px;
            opacity: 0.8;
        }
        
        td {
            padding: 14px 16px;
            border-bottom: 1px solid #ecf0f1;
        }
        
        tr {
            transition: background 0.3s ease;
        }
        
        tr:hover {
            background-color: #f8f9fa;
        }
        
        .subject-row td {
            font-weight: 600;
            background-color: #f1f8ff;
        }
        
        .top-student {
            background-color: #e8f5e9;
        }
        
        .bottom-student {
            background-color: #ffebee;
        }
        
        .chart-container {
            height: 280px;
            position: relative;
            margin-top: 20px;
        }
        
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 20px;
        }
        
        .stat-item {
            background: linear-gradient(135deg, #f8f9fa, #e9ecef);
            padding: 20px;
            border-radius: 12px;
            text-align: center;
            transition: all 0.4s ease;
            box-shadow: 0 4px 10px rgba(0,0,0,0.05);
        }
        
        .stat-item:hover {
            background: linear-gradient(135deg, #e3f2fd, #bbdefb);
            transform: translateY(-5px);
            box-shadow: 0 8px 20px rgba(0,0,0,0.08);
        }
        
        .stat-value {
            font-size: 2.2rem;
            font-weight: 800;
            color: #3498db;
            margin: 15px 0;
            text-shadow: 0 2px 3px rgba(0,0,0,0.1);
        }
        
        .stat-label {
            font-size: 1.1rem;
            color: #5a6268;
            font-weight: 500;
        }
        
        .highlight {
            color: #e74c3c;
            font-weight: 700;
        }
        
        .good-score {
            color: #27ae60;
            font-weight: 700;
        }
        
        .avg-score {
            color: #f39c12;
            font-weight: 700;
        }
        
        .low-score {
            color: #e74c3c;
            font-weight: 700;
        }
        
        .analysis-section {
            display: none;
            opacity: 0;
            transform: translateY(20px);
            transition: opacity 0.6s ease, transform 0.6s ease;
        }
        
        .show-analysis {
            display: block;
            opacity: 1;
            transform: translateY(0);
        }
        
        footer {
            text-align: center;
            padding: 30px 0;
            color: #5a6268;
            font-size: 1rem;
            margin-top: 40px;
            border-top: 1px solid #dae0e5;
        }
        
        .copyright {
            font-size: 1.1rem;
            font-weight: 600;
            margin-top: 10px;
            color: #2c3e50;
        }
        
        @media (max-width: 768px) {
            .dashboard {
                grid-template-columns: 1fr;
            }
            
            .controls {
                flex-direction: column;
            }
            
            .btn {
                width: 100%;
                justify-content: center;
                margin-bottom: 10px;
            }
            
            .stats-grid {
                grid-template-columns: 1fr;
            }
            
            header h1 {
                font-size: 2.2rem;
            }
            
            header p {
                font-size: 1.1rem;
            }
        }