/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette */
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --success-color: #059669;
    --warning-color: #d97706;
    --error-color: #dc2626;
    
    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    --gradient-secondary: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
    --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-card: linear-gradient(145deg, var(--white) 0%, var(--gray-50) 100%);
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Typography */
    --font-family: 'Cairo', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 0.15s ease-in-out;
    --transition-normal: 0.3s ease-in-out;
    --transition-slow: 0.5s ease-in-out;
    
    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal: 1040;
    --z-popover: 1050;
    --z-tooltip: 1060;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--gray-800);
    background-color: var(--white);
    overflow-x: hidden;
    direction: rtl;
    text-align: right;
}

/* Loading Screen */
#loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--gradient-primary);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    transition: opacity 0.5s ease-in-out;
}

.loader {
    text-align: center;
    color: var(--white);
}

.book {
    width: 60px;
    height: 40px;
    position: relative;
    margin: 0 auto 20px;
    transform-style: preserve-3d;
    animation: bookFlip 2s infinite;
}

.page {
    position: absolute;
    width: 100%;
    height: 100%;
    background: var(--white);
    border-radius: 3px;
    box-shadow: var(--shadow-md);
}

.page:nth-child(1) {
    transform: rotateY(0deg);
    animation: page1 2s infinite;
}

.page:nth-child(2) {
    transform: rotateY(30deg);
    animation: page2 2s infinite;
}

.page:nth-child(3) {
    transform: rotateY(60deg);
    animation: page3 2s infinite;
}

@keyframes bookFlip {
    0%, 100% { transform: rotateY(0deg); }
    50% { transform: rotateY(180deg); }
}

@keyframes page1 {
    0%, 100% { transform: rotateY(0deg); }
    50% { transform: rotateY(-30deg); }
}

@keyframes page2 {
    0%, 100% { transform: rotateY(30deg); }
    50% { transform: rotateY(-60deg); }
}

@keyframes page3 {
    0%, 100% { transform: rotateY(60deg); }
    50% { transform: rotateY(-90deg); }
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    z-index: var(--z-fixed);
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-lg);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-4);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-logo i {
    font-size: var(--font-size-2xl);
}

.nav-menu {
    display: flex;
    gap: var(--spacing-8);
    list-style: none;
}

.nav-link {
    color: var(--gray-700);
    text-decoration: none;
    font-weight: 500;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    background: var(--gray-50);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: all var(--transition-normal);
    transform: translateX(-50%);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 80%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--gray-700);
    border-radius: var(--radius-full);
    transition: all var(--transition-normal);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    background: var(--gradient-hero);
    position: relative;
    display: flex;
    align-items: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.1;
}

.floating-elements {
    position: absolute;
    width: 100%;
    height: 100%;
}

.floating-book,
.floating-pencil,
.floating-lightbulb,
.floating-star {
    position: absolute;
    font-size: 2rem;
    color: var(--white);
    animation: float 6s ease-in-out infinite;
}

.floating-book {
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.floating-pencil {
    top: 60%;
    left: 80%;
    animation-delay: 1s;
}

.floating-lightbulb {
    top: 30%;
    left: 85%;
    animation-delay: 2s;
}

.floating-star {
    top: 70%;
    left: 15%;
    animation-delay: 3s;
}

@keyframes float {
    0%, 100% { transform: translateY(0px) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(10deg); }
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-4);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-16);
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-text {
    color: var(--white);
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    margin-bottom: var(--spacing-6);
    line-height: 1.2;
}

.gradient-text {
    background: linear-gradient(45deg, #fff, #e0e7ff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: block;
}

.subtitle {
    display: block;
    font-size: var(--font-size-2xl);
    font-weight: 600;
    margin-top: var(--spacing-2);
    opacity: 0.9;
}

.hero-description {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-8);
    opacity: 0.9;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-4);
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-4) var(--spacing-6);
    border: none;
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

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

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

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.study-illustration {
    position: relative;
    width: 300px;
    height: 300px;
}

.student-avatar {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 80px;
    background: var(--white);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: var(--primary-color);
    box-shadow: var(--shadow-xl);
    z-index: 3;
}

.books-stack {
    position: absolute;
    bottom: 20%;
    left: 50%;
    transform: translateX(-50%);
}

.book {
    width: 60px;
    height: 8px;
    border-radius: var(--radius-sm);
    margin-bottom: 4px;
    box-shadow: var(--shadow-md);
}

.book-1 {
    background: var(--accent-color);
    transform: rotate(-5deg);
}

.book-2 {
    background: var(--secondary-color);
    transform: rotate(2deg);
}

.book-3 {
    background: var(--error-color);
    transform: rotate(-3deg);
}

.scroll-indicator {
    position: absolute;
    bottom: var(--spacing-8);
    left: 50%;
    transform: translateX(-50%);
    color: var(--white);
    animation: bounce 2s infinite;
}

.scroll-arrow {
    font-size: var(--font-size-2xl);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
    40% { transform: translateX(-50%) translateY(-10px); }
    60% { transform: translateX(-50%) translateY(-5px); }
}

/* Font Controls */
.font-controls {
    position: fixed;
    left: var(--spacing-4);
    top: 50%;
    transform: translateY(-50%);
    z-index: var(--z-fixed);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

.font-btn {
    width: 40px;
    height: 40px;
    border: none;
    border-radius: var(--radius-full);
    background: var(--white);
    color: var(--primary-color);
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
}

.font-btn:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-xl);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-4);
}

/* Section Styles */
section {
    padding: var(--spacing-20) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-16);
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--spacing-4);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--gradient-primary);
    border-radius: var(--radius-full);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

/* Topics Section */
.topics-section {
    background: var(--gray-50);
}

.search-container {
    margin-bottom: var(--spacing-12);
    display: flex;
    justify-content: center;
}

.search-box {
    position: relative;
    max-width: 500px;
    width: 100%;
}

.search-box i {
    position: absolute;
    right: var(--spacing-4);
    top: 50%;
    transform: translateY(-50%);
    color: var(--gray-400);
    font-size: var(--font-size-lg);
}

.search-box input {
    width: 100%;
    padding: var(--spacing-4) var(--spacing-12) var(--spacing-4) var(--spacing-4);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-xl);
    font-size: var(--font-size-base);
    background: var(--white);
    transition: all var(--transition-normal);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-8);
}

.topic-card {
    background: var(--white);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.topic-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.topic-card:hover::before {
    transform: scaleX(1);
}

.topic-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.special-card {
    background: var(--gradient-secondary);
    color: var(--white);
}

.special-card .card-icon {
    color: var(--white);
}

.card-icon {
    width: 60px;
    height: 60px;
    background: var(--gradient-primary);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-6);
    color: var(--white);
    font-size: var(--font-size-2xl);
}

.special-card .card-icon {
    background: rgba(255, 255, 255, 0.2);
}

.topic-card h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-4);
    color: var(--gray-900);
}

.special-card h3 {
    color: var(--white);
}

.topic-card p {
    color: var(--gray-600);
    margin-bottom: var(--spacing-6);
    line-height: 1.6;
}

.special-card p {
    color: rgba(255, 255, 255, 0.9);
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.read-time {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    color: var(--gray-500);
    font-size: var(--font-size-sm);
}

.special-card .read-time {
    color: rgba(255, 255, 255, 0.8);
}

.read-more-btn {
    background: var(--primary-color);
    color: var(--white);
    border: none;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.read-more-btn:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.special-card .read-more-btn {
    background: var(--white);
    color: var(--primary-color);
}

.special-card .read-more-btn:hover {
    background: var(--gray-100);
}

/* About Section */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-16);
    align-items: center;
}

.about-text .section-title {
    text-align: right;
    margin-bottom: var(--spacing-6);
}

.about-description {
    font-size: var(--font-size-lg);
    color: var(--gray-600);
    margin-bottom: var(--spacing-8);
    line-height: 1.8;
}

.features-list {
    margin-bottom: var(--spacing-8);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    margin-bottom: var(--spacing-4);
    font-size: var(--font-size-base);
}

.feature-item i {
    color: var(--success-color);
    font-size: var(--font-size-lg);
}

.phone-mockup {
    width: 250px;
    height: 500px;
    background: var(--gray-900);
    border-radius: 30px;
    padding: 20px;
    position: relative;
    margin: 0 auto;
    box-shadow: var(--shadow-2xl);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: var(--white);
    border-radius: 20px;
    overflow: hidden;
    position: relative;
}

.app-interface {
    padding: var(--spacing-4);
    height: 100%;
}

.app-header {
    background: var(--gradient-primary);
    color: var(--white);
    padding: var(--spacing-4);
    text-align: center;
    font-weight: 600;
    margin: calc(-1 * var(--spacing-4)) calc(-1 * var(--spacing-4)) var(--spacing-6);
}

.app-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    padding: var(--spacing-4);
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-3);
}

.app-item i {
    color: var(--primary-color);
    font-size: var(--font-size-lg);
}

/* Contact Section */
.contact-content {
    max-width: 800px;
    margin: 0 auto;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-6);
    padding: var(--spacing-6);
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-6);
    transition: all var(--transition-normal);
}

.contact-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.contact-icon {
    width: 60px;
    height: 60px;
    background: var(--gradient-primary);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    font-size: var(--font-size-xl);
}

.contact-details h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--spacing-2);
}

.contact-details p {
    color: var(--gray-600);
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--white);
    padding: var(--spacing-16) 0 var(--spacing-8);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-12);
    margin-bottom: var(--spacing-12);
}

.footer-section h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-6);
    color: var(--white);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-4);
}

.footer-logo i {
    font-size: var(--font-size-2xl);
    color: var(--primary-light);
}

.footer-description {
    color: var(--gray-300);
    margin-bottom: var(--spacing-6);
    line-height: 1.6;
}

.social-links {
    display: flex;
    gap: var(--spacing-3);
}

.social-link {
    width: 40px;
    height: 40px;
    background: var(--gray-800);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    text-decoration: none;
    transition: all var(--transition-normal);
}

.social-link:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-3);
}

.footer-links a {
    color: var(--gray-300);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.footer-links a:hover {
    color: var(--primary-light);
}

.app-download-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    background: var(--gray-800);
    color: var(--white);
    text-decoration: none;
    padding: var(--spacing-3) var(--spacing-4);
    border-radius: var(--radius-lg);
    transition: all var(--transition-normal);
    margin-top: var(--spacing-4);
}

.app-download-btn:hover {
    background: var(--gray-700);
    transform: translateY(-2px);
}

.app-download-btn i {
    font-size: var(--font-size-2xl);
    color: var(--primary-light);
}

.footer-bottom {
    border-top: 1px solid var(--gray-800);
    padding-top: var(--spacing-8);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-4);
}

.copyright {
    color: var(--gray-400);
}

.footer-links-bottom {
    display: flex;
    gap: var(--spacing-6);
}

.footer-links-bottom a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.footer-links-bottom a:hover {
    color: var(--primary-light);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: var(--z-modal);
    backdrop-filter: blur(5px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease-in-out;
}

.modal-content {
    background: var(--white);
    border-radius: var(--radius-2xl);
    max-width: 800px;
    max-height: 90vh;
    width: 90%;
    overflow: hidden;
    box-shadow: var(--shadow-2xl);
    animation: slideUp 0.3s ease-in-out;
}

.modal-header {
    background: var(--gradient-primary);
    color: var(--white);
    padding: var(--spacing-6);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 {
    font-size: var(--font-size-2xl);
    font-weight: 600;
}

.close-btn {
    background: none;
    border: none;
    color: var(--white);
    font-size: var(--font-size-xl);
    cursor: pointer;
    padding: var(--spacing-2);
    border-radius: var(--radius-md);
    transition: background var(--transition-normal);
}

.close-btn:hover {
    background: rgba(255, 255, 255, 0.1);
}

.modal-body {
    padding: var(--spacing-8);
    max-height: 60vh;
    overflow-y: auto;
    line-height: 1.8;
}

.modal-body h3 {
    color: var(--gray-900);
    margin-bottom: var(--spacing-6);
    font-size: var(--font-size-xl);
}

.modal-body p {
    margin-bottom: var(--spacing-4);
    color: var(--gray-700);
}

.modal-body .highlight {
    color: var(--primary-color);
    font-weight: 600;
}

.modal-body .important {
    background: var(--accent-color);
    color: var(--white);
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--radius-md);
    display: inline-block;
    margin: var(--spacing-2) 0;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: var(--spacing-8);
    right: var(--spacing-8);
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    opacity: 0;
    visibility: hidden;
    z-index: var(--z-fixed);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

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

@keyframes slideUp {
    from { transform: translateY(50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

@keyframes slideInRight {
    from { transform: translateX(50px); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

@keyframes slideInLeft {
    from { transform: translateX(-50px); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-12);
        text-align: center;
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-12);
    }
    
    .topics-grid {
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        right: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--white);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: var(--spacing-8);
        transition: right var(--transition-normal);
        box-shadow: var(--shadow-lg);
    }
    
    .nav-menu.active {
        right: 0;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-toggle.active .bar:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .nav-toggle.active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active .bar:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
    
    .hero-title {
        font-size: var(--font-size-4xl);
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .font-controls {
        left: var(--spacing-2);
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
    
    .modal-content {
        width: 95%;
        margin: var(--spacing-4);
    }
    
    .modal-body {
        padding: var(--spacing-6);
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .section-title {
        font-size: var(--font-size-3xl);
    }
    
    .btn {
        padding: var(--spacing-3) var(--spacing-5);
        font-size: var(--font-size-sm);
    }
    
    .topic-card {
        padding: var(--spacing-6);
    }
    
    .contact-item {
        flex-direction: column;
        text-align: center;
    }
    
    .phone-mockup {
        width: 200px;
        height: 400px;
    }
}

/* Print Styles */
@media print {
    .navbar,
    .font-controls,
    .back-to-top,
    .modal {
        display: none !important;
    }
    
    .hero {
        min-height: auto;
        padding: var(--spacing-8) 0;
    }
    
    section {
        padding: var(--spacing-8) 0;
    }
    
    .topic-card {
        break-inside: avoid;
        margin-bottom: var(--spacing-4);
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --gray-600: #000000;
        --gray-700: #000000;
        --gray-800: #000000;
        --gray-900: #000000;
    }
    
    .btn {
        border: 2px solid currentColor;
    }
    
    .topic-card {
        border: 2px solid var(--gray-300);
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .floating-elements {
        display: none;
    }
    
    .scroll-indicator {
        animation: none;
    }
}