:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #f97316;
    --accent: #10b981;
    --dark: #1e293b;
    --gray: #64748b;
    --light: #f1f5f9;
    --white: #ffffff;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background: var(--white);
    overflow-x: hidden;
}

h1, h2, h3, h4 {
    font-family: 'Poppins', sans-serif;
    font-weight: 700;
    line-height: 1.2;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    gap: 2rem;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--dark);
}

.logo-icon {
    font-size: 1.75rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0.5rem;
    align-items: center;
}

.nav-link {
    padding: 0.5rem 1rem;
    border-radius: 8px;
    color: var(--dark);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
}

.nav-link:hover, .nav-link.active {
    background: var(--light);
    color: var(--primary);
}

.has-submenu {
    position: relative;
}

.submenu {
    position: absolute;
    top: 100%;
    left: 0;
    background: var(--white);
    min-width: 220px;
    box-shadow: var(--shadow-lg);
    border-radius: var(--radius);
    padding: 0.5rem;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    list-style: none;
}

.has-submenu:hover .submenu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.submenu a {
    display: block;
    padding: 0.6rem 1rem;
    border-radius: 8px;
    color: var(--dark);
    font-size: 0.9rem;
}

.submenu a:hover {
    background: var(--light);
    color: var(--primary);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 24px;
    height: 3px;
    background: var(--dark);
    border-radius: 2px;
    transition: var(--transition);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.search-box {
    display: flex;
    align-items: center;
    background: var(--light);
    border-radius: 8px;
    padding: 0.4rem 0.8rem;
    gap: 0.5rem;
}

.search-box input {
    border: none;
    background: transparent;
    outline: none;
    font-size: 0.9rem;
    width: 180px;
    font-family: inherit;
}

.search-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, #eff6ff 0%, #fef3c7 100%);
    padding: 4rem 0;
    overflow: hidden;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-badge {
    display: inline-block;
    background: var(--white);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    margin-bottom: 1.5rem;
    color: var(--dark);
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.15rem;
    color: var(--gray);
    margin-bottom: 2rem;
    max-width: 540px;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    gap: 2.5rem;
    flex-wrap: wrap;
}

.stat {
    display: flex;
    flex-direction: column;
}

.stat strong {
    font-size: 1.75rem;
    color: var(--primary);
    font-family: 'Poppins', sans-serif;
}

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

.hero-image img {
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-15px); }
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.85rem 1.75rem;
    border-radius: 10px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    font-family: inherit;
    text-align: center;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: var(--white);
}

.btn-secondary {
    background: var(--white);
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-secondary:hover {
    background: var(--primary);
    color: var(--white);
    transform: translateY(-2px);
}

/* Features */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    padding: 4rem 1.5rem;
    margin-top: -3rem;
    position: relative;
    z-index: 10;
}

.feature-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.feature-card p {
    color: var(--gray);
    font-size: 0.95rem;
}

/* Section Header */
.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    margin-bottom: 0.75rem;
    color: var(--dark);
}

.section-header p {
    color: var(--gray);
    font-size: 1.1rem;
}

/* Disciplines */
.disciplines {
    padding: 4rem 1.5rem;
}

.disciplines-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.discipline-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
    border: 2px solid transparent;
    color: var(--dark);
}

.discipline-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
    color: var(--dark);
}

.discipline-icon {
    width: 120px;
    height: 120px;
    margin: 0 auto 1rem;
}

.discipline-icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.discipline-card h3 {
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.discipline-card p {
    color: var(--gray);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.discipline-level {
    display: inline-block;
    background: var(--light);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--primary);
    font-weight: 600;
}

/* Simulados */
.simulados {
    padding: 4rem 1.5rem;
    background: var(--light);
}

.simulados-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.simulado-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.simulado-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.simulado-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.simulado-badge {
    background: var(--primary);
    color: var(--white);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.simulado-time {
    color: var(--gray);
    font-size: 0.9rem;
}

.simulado-card h3 {
    margin-bottom: 0.75rem;
    color: var(--dark);
}

.simulado-card > p {
    color: var(--gray);
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.simulado-meta {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--gray);
}

.simulado-card .btn {
    width: 100%;
}

/* Continue Studying */
.continue-studying {
    padding: 4rem 1.5rem;
}

.continue-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

/* Subject Hero */
.subject-hero {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    padding: 3rem 0;
}

.subject-hero-content {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 3rem;
    align-items: center;
}

.subject-icon {
    width: 200px;
    height: 200px;
}

.subject-icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.subject-badge {
    display: inline-block;
    background: var(--primary);
    color: var(--white);
    padding: 0.3rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.subject-title {
    font-size: clamp(2rem, 5vw, 3rem);
    margin-bottom: 1rem;
    color: var(--dark);
}

.subject-description {
    font-size: 1.1rem;
    color: var(--gray);
    margin-bottom: 1.5rem;
    max-width: 600px;
}

.subject-stats {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    font-weight: 500;
    color: var(--dark);
}

/* Breadcrumb */
.breadcrumb {
    padding: 1rem 1.5rem;
    background: var(--light);
}

.breadcrumb ol {
    list-style: none;
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    font-size: 0.9rem;
}

.breadcrumb li:not(:last-child)::after {
    content: '›';
    margin-left: 0.5rem;
    color: var(--gray);
}

.breadcrumb a {
    color: var(--primary);
}

.breadcrumb li[aria-current="page"] {
    color: var(--gray);
}

/* Filters */
.filters {
    display: flex;
    gap: 1rem;
    padding: 2rem 1.5rem;
    flex-wrap: wrap;
    background: var(--white);
    border-bottom: 1px solid var(--light);
}

.filter-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.filter-group label {
    font-weight: 600;
    font-size: 0.9rem;
}

.filter-select {
    padding: 0.5rem 1rem;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    font-family: inherit;
    font-size: 0.9rem;
    background: var(--white);
    cursor: pointer;
}

/* Topics */
.topics {
    padding: 3rem 1.5rem;
}

.topics h2 {
    text-align: center;
    margin-bottom: 2rem;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.topic-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-left: 4px solid var(--primary);
}

.topic-card:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
}

.topic-card h3 {
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.topic-card p {
    color: var(--gray);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.topic-meta {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--gray);
    margin-bottom: 1rem;
}

.difficulty {
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
}

.difficulty.facil { background: #dcfce7; color: #166534; }
.difficulty.medio { background: #fef3c7; color: #92400e; }
.difficulty.dificil { background: #fee2e2; color: #991b1b; }

/* Quiz */
.quiz-section {
    padding: 3rem 1.5rem;
    background: var(--light);
}

.quiz-section h2 {
    text-align: center;
    margin-bottom: 2rem;
}

.quiz-container {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    max-width: 800px;
    margin: 0 auto;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.quiz-progress {
    flex: 1;
    min-width: 200px;
}

.progress-bar {
    height: 8px;
    background: var(--light);
    border-radius: 4px;
    overflow: hidden;
    margin-top: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transition: width 0.3s;
    width: 20%;
}

.quiz-timer, .quiz-score {
    font-weight: 600;
    color: var(--dark);
    font-size: 1rem;
}

.quiz-content {
    margin-bottom: 2rem;
}

.quiz-question {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--dark);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.quiz-option {
    padding: 1rem 1.25rem;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    cursor: pointer;
    transition: var(--transition);
    background: var(--white);
    text-align: left;
    font-family: inherit;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.quiz-option:hover {
    border-color: var(--primary);
    background: #eff6ff;
}

.quiz-option.selected {
    border-color: var(--primary);
    background: #eff6ff;
}

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

.quiz-option.incorrect {
    border-color: var(--error);
    background: #fee2e2;
}

.quiz-option input[type="radio"] {
    margin: 0;
}

.quiz-option-letter {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--light);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    flex-shrink: 0;
}

.quiz-actions {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
}

.quiz-result {
    text-align: center;
    padding: 2rem;
}

.quiz-result h3 {
    font-size: 1.75rem;
    margin-bottom: 1rem;
}

.quiz-result .score-display {
    font-size: 3rem;
    font-weight: 800;
    color: var(--primary);
    margin: 1rem 0;
}

/* Related */
.related {
    padding: 3rem 1.5rem;
}

.related h2 {
    text-align: center;
    margin-bottom: 2rem;
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
}

.related-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
    color: var(--dark);
}

.related-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    color: var(--dark);
}

.related-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
}

.related-card h3 {
    margin-bottom: 0.5rem;
}

.related-card p {
    color: var(--gray);
    font-size: 0.9rem;
}

/* Tips */
.tips {
    padding: 3rem 1.5rem;
    background: var(--light);
}

.tips h2 {
    text-align: center;
    margin-bottom: 2rem;
}

.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.tip-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border-top: 4px solid var(--accent);
}

.tip-card h4 {
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.tip-card p {
    color: var(--gray);
    font-size: 0.95rem;
}

/* Footer */
.footer {
    background: var(--dark);
    color: var(--white);
    padding: 3rem 0 1rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-col h4 {
    margin-bottom: 1rem;
    color: var(--white);
}

.footer-col p {
    color: #cbd5e1;
    font-size: 0.9rem;
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: 0.5rem;
}

.footer-col ul a {
    color: #cbd5e1;
    font-size: 0.9rem;
}

.footer-col ul a:hover {
    color: var(--white);
}

.footer-bottom {
    border-top: 1px solid #334155;
    padding-top: 1.5rem;
    text-align: center;
    color: #94a3b8;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 968px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-lg);
        transform: translateY(-150%);
        transition: var(--transition);
        max-height: calc(100vh - 70px);
        overflow-y: auto;
    }
    
    .nav-menu.active {
        transform: translateY(0);
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
    
    .submenu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        display: none;
    }
    
    .has-submenu.active .submenu {
        display: block;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-description {
        margin-left: auto;
        margin-right: auto;
    }
    
    .hero-cta {
        justify-content: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .subject-hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .subject-icon {
        margin: 0 auto;
    }
    
    .subject-stats {
        justify-content: center;
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
    
    .search-box input {
        width: 120px;
    }
}

@media (max-width: 480px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-stats {
        gap: 1.5rem;
    }
    
    .filters {
        flex-direction: column;
    }
    
    .filter-group {
        width: 100%;
    }
    
    .filter-select {
        flex: 1;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-in {
    animation: fadeInUp 0.6s ease-out forwards;
}

/* Accessibility */
:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 2px;
}

/* Print */
@media print {
    .header, .footer, .nav-toggle, .quiz-actions, .btn {
        display: none !important;
    }
}

/* Topic Content Page */
.content-section {
    padding: 3rem 1.5rem;
}

.content-section h2 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
    color: var(--dark);
    border-bottom: 3px solid var(--primary);
    padding-bottom: 0.5rem;
}

.content-section h3 {
    font-size: 1.25rem;
    margin: 1.5rem 0 0.75rem;
    color: var(--primary);
}

.content-section p {
    color: var(--gray);
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: 1rem;
}

.content-section ul, .content-section ol {
    margin: 1rem 0;
    padding-left: 1.5rem;
}

.content-section li {
    color: var(--gray);
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.content-box {
    background: var(--light);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 1.5rem 0;
    border-left: 4px solid var(--primary);
}

.content-box.highlight {
    border-left-color: var(--secondary);
    background: #fff7ed;
}

.content-box.success {
    border-left-color: var(--success);
    background: #f0fdf4;
}

.content-box.warning {
    border-left-color: var(--warning);
    background: #fffbeb;
}

.formula-box {
    background: var(--white);
    border: 2px solid var(--primary);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 1.5rem 0;
    text-align: center;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--dark);
}

.example-box {
    background: var(--white);
    border: 1px solid #e2e8f0;
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 1rem 0;
}

.example-box .example-title {
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 0.75rem;
    font-size: 0.9rem;
    text-transform: uppercase;
}

/* Exercises Section */
.exercises-section {
    padding: 3rem 1.5rem;
    background: var(--light);
}

.exercise-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.exercise-card .exercise-number {
    display: inline-block;
    background: var(--primary);
    color: var(--white);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    text-align: center;
    line-height: 32px;
    font-weight: 600;
    font-size: 0.85rem;
    margin-right: 0.75rem;
}

.exercise-card .exercise-question {
    font-weight: 500;
    color: var(--dark);
    margin-bottom: 1rem;
}

.exercise-card .exercise-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.exercise-card .exercise-option {
    padding: 0.75rem 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    font-size: 0.95rem;
    text-align: left;
    background: var(--white);
}

.exercise-card .exercise-option:hover {
    border-color: var(--primary);
    background: #eff6ff;
}

.exercise-card .exercise-option.selected {
    border-color: var(--primary);
    background: #eff6ff;
}

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

.exercise-card .exercise-option.incorrect {
    border-color: var(--error);
    background: #fee2e2;
}

.exercise-card .exercise-explanation {
    display: none;
    margin-top: 1rem;
    padding: 1rem;
    background: #f0fdf4;
    border-radius: 8px;
    font-size: 0.9rem;
    color: var(--dark);
}

.exercise-card .exercise-explanation.show {
    display: block;
}

.exercise-difficulty {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 0.5rem;
}

/* Simulado Section */
.simulado-section {
    padding: 3rem 1.5rem;
}

.simulado-container {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    max-width: 900px;
    margin: 0 auto;
}

.simulado-header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 2px solid var(--light);
}

.simulado-header h2 {
    border: none;
    padding: 0;
    margin-bottom: 0.5rem;
}

.simulado-info {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    color: var(--gray);
    font-size: 0.9rem;
}

.simulado-question {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--light);
}

.simulado-question:last-child {
    border-bottom: none;
}

.simulado-question .question-text {
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.simulado-question .question-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.simulado-question .question-option {
    padding: 0.75rem 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    font-size: 0.95rem;
    text-align: left;
    background: var(--white);
}

.simulado-question .question-option:hover {
    border-color: var(--primary);
    background: #eff6ff;
}

.simulado-question .question-option.selected {
    border-color: var(--primary);
    background: #eff6ff;
}

.simulado-result {
    display: none;
    text-align: center;
    padding: 2rem;
}

.simulado-result .result-score {
    font-size: 3rem;
    font-weight: 800;
    color: var(--primary);
    margin: 1rem 0;
}

.simulado-result .result-message {
    font-size: 1.25rem;
    color: var(--dark);
    margin-bottom: 1.5rem;
}

/* FAQ Section */
.faq-section {
    padding: 3rem 1.5rem;
    background: var(--light);
}

.faq-item {
    background: var(--white);
    border-radius: var(--radius);
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-question {
    padding: 1.25rem 1.5rem;
    font-weight: 600;
    color: var(--dark);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--light);
}

.faq-question::after {
    content: '+';
    font-size: 1.5rem;
    color: var(--primary);
    transition: var(--transition);
}

.faq-item.active .faq-question::after {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 1.5rem;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-item.active .faq-answer {
    padding: 0 1.5rem 1.25rem;
    max-height: 500px;
}

.faq-answer p {
    color: var(--gray);
    line-height: 1.7;
}

/* Back to topic link */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary);
    font-weight: 500;
    margin-bottom: 1.5rem;
    transition: var(--transition);
}

.back-link:hover {
    color: var(--primary-dark);
}

/* Tabs for difficulty levels */
.difficulty-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.difficulty-tab {
    padding: 0.75rem 1.5rem;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    background: var(--white);
    cursor: pointer;
    font-family: inherit;
    font-weight: 500;
    transition: var(--transition);
}

.difficulty-tab:hover {
    border-color: var(--primary);
}

.difficulty-tab.active {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
}