:root {
            --primary: #4f46e5;
            --success: #10b981;
            --danger: #ef4444;
            --background: #f3f4f6;
            --card-bg: #ffffff;
            --text: #1f2937;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background-color: var(--background);
            color: var(--text);
            margin: 0;
            padding: 20px;
            display: flex;
            justify-content: center;
        }

        .container {
            max-width: 800px;
            width: 100%;
        }

        header {
            text-align: center;
            background: var(--card-bg);
            padding: 20px;
            border-radius: 12px;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
            margin-bottom: 20px;
        }

        h1 {
            margin: 0 0 10px 0;
            color: var(--primary);
            font-size: 1.5rem;
        }

        .score-board {
            font-size: 1.2rem;
            font-weight: bold;
            color: var(--primary);
        }

        .question-card {
            background: var(--card-bg);
            border-radius: 12px;
            padding: 20px;
            margin-bottom: 20px;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
            position: relative;
            transition: border 0.3s ease;
        }

        .question-card.correct {
            border: 3px solid var(--success);
        }

        .question-card.incorrect {
            border: 3px solid var(--danger);
        }

        .question-title {
            font-weight: 600;
            font-size: 1.1rem;
            margin-bottom: 15px;
        }

        .options-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 10px;
        }

        @media (max-width: 600px) {
            .options-grid {
                grid-template-columns: 1fr;
            }
        }

        .option-btn {
            background: #f9fafb;
            border: 2px solid #e5e7eb;
            border-radius: 8px;
            padding: 12px 15px;
            text-align: left;
            font-size: 1rem;
            cursor: pointer;
            transition: all 0.2s ease;
            width: 100%;
        }

        .option-btn:hover:not([disabled]) {
            background: #edf2f7;
            border-color: var(--primary);
        }

        .option-btn.correct-choice {
            background-color: #d1fae5;
            border-color: var(--success);
            color: #065f46;
            font-weight: bold;
        }

        .option-btn.wrong-choice {
            background-color: #fee2e2;
            border-color: var(--danger);
            color: #991b1b;
        }

        /* Banner de Felicitaciones e Iconos */
        .feedback-banner {
            display: none;
            align-items: center;
            gap: 10px;
            margin-top: 15px;
            padding: 10px;
            border-radius: 8px;
            background-color: #ecfdf5;
            color: #065f46;
            font-weight: bold;
            animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
        }

        .star-icon {
            font-size: 1.5rem;
            animation: spin 0.6s ease;
        }

        @keyframes popIn {
            0% { transform: scale(0.8); opacity: 0; }
            100% { transform: scale(1); opacity: 1; }
        }

        @keyframes spin {
            0% { transform: rotate(0deg) scale(0); }
            100% { transform: rotate(360deg) scale(1); }
        }

        /* Modal / Ventana Emergente */
        .modal-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.5);
            display: none;
            justify-content: center;
            align-items: center;
            z-index: 1000;
            padding: 15px;
            box-sizing: border-box;
        }

        .modal-content {
            background: white;
            border-radius: 12px;
            padding: 25px;
            max-width: 500px;
            width: 100%;
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
            animation: slideDown 0.3s ease;
        }

        @keyframes slideDown {
            from { transform: translateY(-30px); opacity: 0; }
            to { transform: translateY(0); opacity: 1; }
        }

        .modal-title {
            color: var(--danger);
            font-size: 1.3rem;
            margin-top: 0;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .modal-body {
            margin: 15px 0;
            line-height: 1.6;
        }

        .modal-btn {
            background: var(--primary);
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 6px;
            cursor: pointer;
            font-size: 1rem;
            width: 100%;
        }

        .modal-btn:hover {
            opacity: 0.9;
        }