* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header Styles */
.header {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

.header-content {
    display: flex;
    align-items: center;
    gap: 30px;
}

.header-image {
    width: 120px;
    height: 120px;
    border-radius: 15px;
    object-fit: cover;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.header-text {
    flex: 1;
}

.title {
    font-size: 2.5rem;
    font-weight: 700;
    color: #2d3748;
    margin-bottom: 10px;
    background: linear-gradient(135deg, #667eea, #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 1.1rem;
    color: #718096;
    font-weight: 400;
}

/* Main Content */
.main-content {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

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

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #e2e8f0;
}

.exercise-counter {
    font-size: 1.2rem;
    font-weight: 600;
    color: #4a5568;
}

.score-display {
    font-size: 1.2rem;
    font-weight: 600;
    color: #667eea;
    background: rgba(102, 126, 234, 0.1);
    padding: 10px 20px;
    border-radius: 25px;
}

/* Exercise Card */
.exercise-card {
    background: #f7fafc;
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 30px;
    border: 2px solid #e2e8f0;
    transition: all 0.3s ease;
}

.exercise-question h3 {
    font-size: 1.3rem;
    color: #2d3748;
    margin-bottom: 20px;
    font-weight: 600;
}

.incorrect-sentence {
    background: #fed7d7;
    border: 2px solid #fc8181;
    border-radius: 10px;
    padding: 20px;
    font-size: 1.2rem;
    font-weight: 500;
    color: #c53030;
    margin-bottom: 25px;
    transition: all 0.3s ease;
    text-align: center;
}

.incorrect-sentence.correct {
    background: #c6f6d5;
    border-color: #68d391;
    color: #2f855a;
}

.answer-section {
    margin-bottom: 25px;
}

.answer-section label {
    display: block;
    font-weight: 600;
    color: #4a5568;
    margin-bottom: 10px;
    font-size: 1.1rem;
}

.answer-input {
    width: 100%;
    padding: 15px 20px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1.1rem;
    margin-bottom: 20px;
    transition: all 0.3s ease;
    font-family: 'Inter', sans-serif;
}

.answer-input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.submit-btn {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 10px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 0 auto;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.submit-btn:disabled {
    background: #a0aec0;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Feedback Section */
.feedback-section {
    background: white;
    border-radius: 15px;
    padding: 25px;
    border: 2px solid #e2e8f0;
    margin-top: 20px;
}

.feedback-content > div {
    margin-bottom: 20px;
}

.feedback-content h4 {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: #2d3748;
}

.correct-answer h4 {
    color: #2f855a;
}

.explanation h4 {
    color: #3182ce;
}

.alternatives h4 {
    color: #805ad5;
}

.feedback-content p {
    color: #4a5568;
    line-height: 1.6;
    font-size: 1rem;
}

.alternatives ul {
    list-style: none;
    padding-left: 0;
}

.alternatives li {
    background: #f7fafc;
    padding: 10px 15px;
    border-radius: 8px;
    margin-bottom: 8px;
    border-left: 4px solid #805ad5;
    color: #4a5568;
}

/* Navigation */
.navigation {
    display: flex;
    justify-content: space-between;
    gap: 20px;
}

.nav-btn {
    background: white;
    border: 2px solid #e2e8f0;
    padding: 12px 25px;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    color: #4a5568;
}

.nav-btn:hover:not(:disabled) {
    background: #667eea;
    color: white;
    border-color: #667eea;
    transform: translateY(-2px);
}

.nav-btn:disabled {
    background: #f7fafc;
    color: #a0aec0;
    cursor: not-allowed;
    transform: none;
}

/* Results Modal */
.results-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-content {
    background: white;
    border-radius: 20px;
    padding: 40px;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.modal-header h2 {
    display: flex;
    align-items: center;
    gap: 15px;
    color: #2d3748;
    margin-bottom: 30px;
    font-size: 1.8rem;
}

.final-score {
    text-align: center;
    margin-bottom: 30px;
}

.final-score h3 {
    color: #2d3748;
    margin-bottom: 15px;
    font-size: 1.5rem;
}

.score-percentage {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(135deg, #667eea, #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.answers-summary h4 {
    color: #4a5568;
    margin-bottom: 15px;
    font-size: 1.2rem;
}

.answer-item {
    background: #f7fafc;
    border-radius: 10px;
    padding: 15px;
    margin-bottom: 10px;
    border-left: 4px solid #e2e8f0;
}

.answer-item.correct {
    border-left-color: #68d391;
    background: #f0fff4;
}

.answer-item.incorrect {
    border-left-color: #fc8181;
    background: #fffaf0;
}

.answer-item-header {
    font-weight: 600;
    margin-bottom: 5px;
    color: #2d3748;
}

.answer-item-content {
    color: #4a5568;
    font-size: 0.9rem;
}

.restart-btn {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 10px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 20px auto 0;
}

.restart-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .header-content {
        flex-direction: column;
        text-align: center;
        gap: 20px;
    }
    
    .header-image {
        width: 100px;
        height: 100px;
    }
    
    .title {
        font-size: 2rem;
    }
    
    .main-content {
        padding: 25px;
    }
    
    .exercise-header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
    
    .navigation {
        flex-direction: column;
    }
    
    .modal-content {
        padding: 25px;
        margin: 20px;
    }
}

@media (max-width: 480px) {
    .title {
        font-size: 1.8rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .main-content {
        padding: 20px;
    }
    
    .exercise-card {
        padding: 20px;
    }
    
    .score-percentage {
        font-size: 2.5rem;
    }
}