* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        body {
            background-color: #f5f7fa;
            color: #333;
            padding: 20px;
            line-height: 1.6;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
        }

        .converter-card {
            background-color: white;
            border-radius: 12px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            padding: 30px;
            margin-bottom: 30px;
        }

        .converter-header {
            text-align: center;
            margin-bottom: 30px;
        }

        .converter-header h2 {
            color: #2c3e50;
            margin-bottom: 10px;
        }

        .converter-header p {
            color: #7f8c8d;
            font-size: 1.1rem;
        }

        .converter-row {
            display: flex;
            gap: 20px;
            margin-bottom: 30px;
        }

        .converter-column {
            flex: 1;
            display: flex;
            flex-direction: column;
        }

        .converter-column label {
            margin-bottom: 10px;
            font-weight: 600;
            color: #2c3e50;
        }

        input, select {
            width: 100%;
            box-sizing: border-box;
            padding: 12px;
            border: 1px solid #d1d5db;
            border-radius: 6px;
            font-size: 16px;
        }

        input:focus, select:focus {
            outline: none;
            border-color: #3498db;
            box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
        }

        .converter-buttons {
            display: flex;
            gap: 15px;
            justify-content: center;
            margin-top: 20px;
        }

        .btn {
            padding: 12px 24px;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
            font-size: 16px;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
        }

        .btn-primary {
            background-color: #3498db;
            color: white;
        }

        .btn-primary:hover {
            background-color: #2980b9;
        }

        .btn-secondary {
            background-color: #95a5a6;
            color: white;
        }

        .btn-secondary:hover {
            background-color: #7f8c8d;
        }

        .result-display {
            background-color: #f8f9fa;
            border-radius: 10px;
            padding: 25px;
            margin-top: 30px;
            text-align: center;
            border: 1px solid #e5e7eb;
        }

        .result-title {
            color: #2c3e50;
            margin-bottom: 15px;
            font-size: 1.2rem;
        }

        .result-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 15px;
            margin-top: 20px;
        }

        .result-item {
            background-color: white;
            border-radius: 8px;
            padding: 15px;
            text-align: center;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
        }

        .result-label {
            font-size: 0.9rem;
            color: #7f8c8d;
            margin-bottom: 5px;
        }

        .result-value {
            font-size: 1.5rem;
            font-weight: bold;
            color: #2c3e50;
        }

        .gpa-tables {
            background-color: white;
            border-radius: 12px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            padding: 30px;
            margin-top: 40px;
        }

        .gpa-tables h3 {
            color: #2c3e50;
            margin-bottom: 20px;
            text-align: center;
        }

        .tables-container {
            display: flex;
            gap: 30px;
            flex-wrap: wrap;
            justify-content: center;
        }

        .gpa-table {
            flex: 1;
            min-width: 300px;
        }

        .gpa-table h4 {
            color: #3498db;
            margin-bottom: 15px;
            padding-bottom: 10px;
            border-bottom: 2px solid #f1f5f9;
        }

        table {
            width: 100%;
            border-collapse: collapse;
            background: #fff;
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
        }

        th, td {
            padding: 15px;
            border-bottom: 1px solid #e5e7eb;
            text-align: left;
        }

        th {
            background: #f1f5f9;
            font-weight: 600;
            color: #2c3e50;
        }

        tr:last-child td {
            border-bottom: none;
        }

        tr:hover {
            background-color: #f8f9fa;
        }

        .grade-color {
            display: inline-block;
            width: 20px;
            height: 20px;
            border-radius: 4px;
            margin-right: 8px;
            vertical-align: middle;
        }

        /* Mobile responsive: 1-row layout */
        @media(max-width: 768px) {
            .converter-row {
                flex-direction: column;
                gap: 15px;
            }
            
            .converter-column {
                width: 100%;
            }
            
            .result-grid {
                grid-template-columns: repeat(2, 1fr);
            }
            
            .tables-container {
                flex-direction: column;
            }
            
            .gpa-table {
                min-width: 100%;
            }
        }

        /* Small mobile: 1-row layout for result grid */
        @media(max-width: 480px) {
            .result-grid {
                grid-template-columns: 1fr;
            }
            
            .converter-buttons {
                flex-direction: column;
            }
            
            .btn {
                width: 100%;
            }
        }

        /* Mobile responsive for GPA table */
        @media(max-width: 650px) {
            table, thead, tbody, th, td, tr {
                display: block;
                width: 100%;
            }

            thead tr {
                display: none;
            }

            tr {
                margin-bottom: 15px;
                background: #fff;
                padding: 12px;
                border-radius: 10px;
                border: 1px solid #e5e7eb;
                box-sizing: border-box;
                display: grid;
                grid-template-columns: 1fr 1fr 1fr; /* 3 columns */
                grid-gap: 10px;
            }

            td {
                border: 0;
                padding: 0;
                width: 100%;
                box-sizing: border-box;
            }

            td:before {
                content: attr(data-label);
                font-weight: bold;
                display: block;
                margin-bottom: 4px;
                color: #6b7280;
                font-size: 0.9rem;
            }
        }