:root {
    --primary: #4361ee;
    --primary-dark: #3a0ca3;
    --secondary: #4cc9f0;
    --success: #4ade80;
    --danger: #f72585;
    --warning: #f8961e;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --radius: 12px;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: 'Poppins', sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
    padding: 0 20px;
}

header {
    text-align: center;
    padding: 20px 0;
    margin-bottom: 20px;
    animation: fadeIn 1s ease;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 10px;
    gap: 15px;
}

.logo-icon {
    background: var(--primary);
    color: white;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    box-shadow: var(--shadow);
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--primary), var(--primary-dark));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 5px;
}

.subtitle {
    font-size: 1.1rem;
    color: var(--gray);
}

.app-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: 25px;
    margin-bottom: 30px;
}

.card {
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 25px;
    transition: all 0.3s ease;
    animation: slideUp 0.8s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.welcome-content {
    text-align: center;
}

.welcome-icon {
    font-size: 60px;
    color: var(--primary);
    margin-bottom: 20px;
    animation: bounce 2s infinite;
}

.category-section, .difficulty-section, .settings-section {
    margin-bottom: 25px;
    text-align: left;
}

.category-section h3, .difficulty-section h3, .settings-section h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 15px;
    color: var(--primary-dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.quiz-categories {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 12px;
    margin-bottom: 20px;
}

.category {
    background: var(--light);
    border: 2px solid #e9ecef;
    border-radius: 10px;
    padding: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.category:hover {
    border-color: var(--primary);
    background: #f0f4ff;
}

.category.active {
    border-color: var(--primary);
    background: #e8eeff;
}

.category-icon {
    width: 40px;
    height: 40px;
    background: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 18px;
}

.category-name {
    font-weight: 500;
    font-size: 0.9rem;
}

.difficulty-options {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.difficulty-btn {
    flex: 1;
    padding: 12px;
    border: 2px solid #e9ecef;
    border-radius: 10px;
    background: white;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.difficulty-btn:hover {
    border-color: var(--primary);
    background: #f0f4ff;
}

.difficulty-btn.active {
    border-color: var(--primary);
    background: #e8eeff;
    color: var(--primary);
}

.quiz-settings {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.setting-item {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.setting-item label {
    font-weight: 500;
    font-size: 0.9rem;
}

.setting-item select {
    padding: 12px;
    border: 2px solid #e9ecef;
    border-radius: 10px;
    font-family: 'Poppins', sans-serif;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.setting-item select:focus {
    outline: none;
    border-color: var(--primary);
}

.btn {
    padding: 15px 30px;
    border: none;
    border-radius: 10px;
    font-family: 'Poppins', sans-serif;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(67, 97, 238, 0.3);
}

.btn-secondary {
    background: var(--light);
    color: var(--dark);
    border: 2px solid #e9ecef;
}

.btn-secondary:hover {
    background: #e9ecef;
    border-color: var(--gray);
}

.btn-success {
    background: var(--success);
    color: white;
}

.btn-success:hover {
    background: #22c55e;
    transform: translateY(-3px);
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 2px solid #f1f3f5;
}

.quiz-progress {
    display: flex;
    flex-direction: column;
    gap: 5px;
    flex: 1;
}

.progress-text {
    font-weight: 500;
    color: var(--gray);
    font-size: 0.9rem;
}

.progress-bar {
    height: 8px;
    background: #e9ecef;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--primary);
    width: 0%;
    transition: width 0.5s ease;
}

.quiz-timer {
    background: var(--light);
    padding: 8px 15px;
    border-radius: 20px;
    font-weight: 600;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 8px;
}

.quiz-question {
    font-size: 1.3rem;
    font-weight: 500;
    margin-bottom: 25px;
    line-height: 1.5;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 25px;
}

.option {
    padding: 18px 20px;
    border: 2px solid #e9ecef;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 15px;
    font-weight: 500;
}

.option:hover {
    border-color: var(--primary);
    background: #f0f4ff;
}

.option.selected {
    border-color: var(--primary);
    background: #e8eeff;
    color: var(--primary);
}

.option.correct {
    border-color: var(--success);
    background: #dcfce7;
    color: #166534;
}

.option.incorrect {
    border-color: var(--danger);
    background: #fce7f3;
    color: #9d174d;
}

.option-index {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: #e9ecef;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    flex-shrink: 0;
}

.option.selected .option-index {
    background: var(--primary);
    color: white;
}

.quiz-footer {
    display: flex;
    justify-content: space-between;
    gap: 15px;
}

.quiz-footer .btn {
    width: auto;
    min-width: 150px;
}

.results-container {
    text-align: center;
    padding: 20px;
}

.results-icon {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 40px;
    margin: 0 auto 25px;
    animation: bounce 1s ease infinite alternate;
}

.results-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 15px;
    color: var(--primary-dark);
}

.results-score {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    background: linear-gradient(to right, var(--primary), var(--primary-dark));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.results-text {
    font-size: 1.1rem;
    color: var(--gray);
    margin: 0 auto 30px;
    max-width: 500px;
}

.results-details {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    margin-bottom: 30px;
}

.result-stat {
    background: var(--light);
    border-radius: 10px;
    padding: 20px;
}

.result-stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 5px;
}

.result-stat-label {
    font-size: 0.9rem;
    color: var(--gray);
}

.results-actions {
    display: flex;
    justify-content: center;
    gap: 15px;
}

.results-actions .btn {
    width: auto;
    min-width: 150px;
}

footer {
    text-align: center;
    padding: 20px 0;
    color: var(--gray);
    font-size: 0.9rem;
    margin-top: auto;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 10px;
}

.social-link {
    color: var(--gray);
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

.social-link:hover {
    color: var(--primary);
    transform: translateY(-3px);
}

.hidden {
    display: none !important;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

@keyframes bounce {
    from { transform: translateY(0); }
    to { transform: translateY(-10px); }
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    .card {
        padding: 20px;
    }
    
    .quiz-categories {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
    
    .quiz-settings {
        grid-template-columns: 1fr;
    }
    
    .quiz-footer {
        flex-direction: column;
    }
    
    .quiz-footer .btn {
        width: 100%;
    }
    
    .results-actions {
        flex-direction: column;
    }
    
    .results-actions .btn {
        width: 100%;
    }
}

@media (max-width: 480px) {
    body {
        padding: 10px;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    .container {
        padding: 0 10px;
    }
    
    .quiz-categories {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .difficulty-options {
        flex-direction: column;
    }
}