:root {
            --primary-color: #2c3e50;
            --secondary-color: #3498db;
            --background-color: #f5f7fa;
            --card-color: #ffffff;
            --text-color: #2c3e50;
            --border-radius: 8px;
            --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }

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

        body {
            background-color: var(--background-color);
            color: var(--text-color);
            line-height: 1.6;
            padding: 20px;
        }

        .container {
            max-width: 800px;
            margin: 0 auto;
        }

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

        .logo {
            margin-bottom: 15px;
        }

        .logo h1 {
            color: var(--primary-color);
            font-size: 32px;
            font-weight: 700;
        }

        .logo span {
            color: var(--secondary-color);
        }

        .tabs {
            display: flex;
            margin-bottom: 20px;
            background-color: var(--card-color);
            border-radius: var(--border-radius);
            overflow: hidden;
            box-shadow: var(--box-shadow);
        }

        .tab-btn {
            flex: 1;
            padding: 15px;
            border: none;
            background-color: var(--card-color);
            color: var(--text-color);
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .tab-btn.active {
            background-color: var(--secondary-color);
            color: white;
        }

        .tab-content {
            display: none;
            background-color: var(--card-color);
            border-radius: var(--border-radius);
            padding: 20px;
            box-shadow: var(--box-shadow);
            margin-bottom: 20px;
        }

        .tab-content.active {
            display: block;
        }

        .form-group {
            margin-bottom: 15px;
        }

        .form-group label {
            display: block;
            margin-bottom: 5px;
            font-weight: 600;
        }

        .form-control {
            width: 100%;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: var(--border-radius);
            font-size: 16px;
        }

        .btn {
            background-color: var(--secondary-color);
            color: white;
            border: none;
            padding: 12px 20px;
            border-radius: var(--border-radius);
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
        }

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

        .result-card {
            background-color: var(--card-color);
            border-radius: var(--border-radius);
            padding: 20px;
            box-shadow: var(--box-shadow);
            margin-top: 20px;
            text-align: center;
        }

        .result-card h3 {
            margin-bottom: 10px;
            color: var(--primary-color);
        }

        .result-value {
            font-size: 36px;
            font-weight: 700;
            color: var(--secondary-color);
        }

        table {
            width: 100%;
            border-collapse: collapse;
            margin-bottom: 15px;
        }

        th, td {
            padding: 12px;
            text-align: left;
            border-bottom: 1px solid #ddd;
        }

        th {
            background-color: #f2f2f2;
            font-weight: 600;
        }

        .course-row {
            margin-bottom: 10px;
            display: flex;
            gap: 10px;
        }

        .course-row input, .course-row select {
            flex: 1;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: var(--border-radius);
        }

        .btn-small {
            padding: 5px 10px;
            font-size: 14px;
        }

        .btn-danger {
            background-color: #e74c3c;
        }

        .btn-danger:hover {
            background-color: #c0392b;
        }

        .btn-add {
            margin-top: 10px;
            background-color: #2ecc71;
        }

        .btn-add:hover {
            background-color: #27ae60;
        }

        .semester-card {
            background-color: var(--card-color);
            border-radius: var(--border-radius);
            padding: 15px;
            margin-bottom: 15px;
            box-shadow: var(--box-shadow);
        }

        .semester-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 10px;
        }

        .semester-info {
            display: flex;
            justify-content: space-between;
            margin-top: 10px;
            padding-top: 10px;
            border-top: 1px solid #ddd;
        }

        footer {
            text-align: center;
            margin-top: 30px;
            color: #7f8c8d;
            font-size: 14px;
        }

        @media (max-width: 768px) {
            .course-row {
                flex-direction: column;
                gap: 5px;
            }
        }