/* ============================================
   ULTIMATE SAT - PROFESSIONAL STYLES
   Modern, Clean, Distinctive Design
   ============================================ */

:root {
    /* Colors - Professional Palette */
    --primary-500: #2563eb;
    --primary-600: #1d4ed8;
    --primary-700: #1e40af;
    --accent-500: #f97316;
    --accent-600: #ea580c;
    
    --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;
    
    /* Typography */
    --font-heading: 'Manrope', system-ui, sans-serif;
    --font-body: 'Source Sans 3', system-ui, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Animation */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   BASE STYLES
   ============================================ */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.6;
    color: var(--gray-800);
    background: var(--gray-50);
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.2;
    color: var(--gray-900);
}

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ============================================
   NAVIGATION
   ============================================ */

.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    transition: var(--transition-base);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--gray-900);
}

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

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

.nav-link {
    font-weight: 500;
    color: var(--gray-600);
    position: relative;
    padding: 0.5rem 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-500);
    transition: width var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-500);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 0.25rem;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-700);
    transition: var(--transition-base);
}

/* ============================================
   HERO SECTION
   ============================================ */

.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 70px;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 20%, rgba(37, 99, 235, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(249, 115, 22, 0.08) 0%, transparent 50%);
    z-index: -1;
}

.hero-content {
    max-width: 800px;
    animation: fadeInUp 0.8s ease;
}

.hero-title {
    font-size: clamp(2.5rem, 6vw, 4rem);
    margin-bottom: var(--spacing-md);
    font-weight: 800;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-500), var(--accent-500));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.25rem;
    color: var(--gray-600);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    line-height: 1.7;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    gap: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--gray-200);
}

.stat {
    text-align: center;
}

.stat-number {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-500);
    line-height: 1;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

.stat-divider {
    width: 1px;
    background: var(--gray-200);
}

/* ============================================
   BUTTONS
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    font-weight: 600;
    font-size: 1rem;
    border-radius: 0.75rem;
    transition: all var(--transition-base);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background: var(--primary-500);
    color: white;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.btn-primary:hover {
    background: var(--primary-600);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.3);
}

.btn-secondary {
    background: white;
    color: var(--gray-700);
    border-color: var(--gray-300);
}

.btn-secondary:hover {
    border-color: var(--primary-500);
    color: var(--primary-500);
    transform: translateY(-2px);
}

.btn-large {
    padding: 1.125rem 2rem;
    font-size: 1.125rem;
}

.btn-icon {
    width: 18px;
    height: 18px;
}

/* ============================================
   SECTIONS
   ============================================ */

.section-title {
    font-size: clamp(2rem, 4vw, 2.5rem);
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-weight: 800;
}

.section-subtitle {
    text-align: center;
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto var(--spacing-xl);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
}

.view-all {
    color: var(--primary-500);
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.view-all:hover {
    color: var(--primary-600);
    transform: translateX(4px);
}

/* ============================================
   FEATURES SECTION
   ============================================ */

.features {
    padding: var(--spacing-3xl) 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.feature-card {
    background: white;
    padding: var(--spacing-xl);
    border-radius: 1rem;
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.1);
    border-color: var(--primary-500);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    display: inline-block;
    animation: float 3s ease-in-out infinite;
}

.feature-card:nth-child(1) .feature-icon { animation-delay: 0s; }
.feature-card:nth-child(2) .feature-icon { animation-delay: 0.2s; }
.feature-card:nth-child(3) .feature-icon { animation-delay: 0.4s; }
.feature-card:nth-child(4) .feature-icon { animation-delay: 0.6s; }
.feature-card:nth-child(5) .feature-icon { animation-delay: 0.8s; }
.feature-card:nth-child(6) .feature-icon { animation-delay: 1s; }

.feature-title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    font-weight: 700;
}

.feature-description {
    color: var(--gray-600);
    line-height: 1.7;
}

/* ============================================
   POPULAR RESOURCES
   ============================================ */

.popular-resources {
    padding: var(--spacing-3xl) 0;
    background: white;
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.resource-card {
    background: var(--gray-50);
    border-radius: 1rem;
    overflow: hidden;
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
    cursor: pointer;
}

.resource-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
}

.resource-card-header {
    background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
    padding: var(--spacing-lg);
    color: white;
}

.resource-category {
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    opacity: 0.9;
    margin-bottom: 0.5rem;
}

.resource-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0;
}

.resource-card-body {
    padding: var(--spacing-lg);
}

.resource-description {
    color: var(--gray-600);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.resource-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.875rem;
    color: var(--gray-500);
    margin-bottom: var(--spacing-md);
}

.download-btn {
    width: 100%;
    justify-content: center;
    background: var(--primary-500);
    color: white;
    padding: 0.75rem;
    border-radius: 0.5rem;
}

.download-btn:hover {
    background: var(--primary-600);
}

.resource-card-skeleton {
    background: var(--gray-100);
    border-radius: 1rem;
    height: 300px;
    animation: pulse 2s ease-in-out infinite;
}

/* ============================================
   ABOUT SECTION
   ============================================ */

.about {
    padding: var(--spacing-3xl) 0;
    background: var(--gray-900);
    color: white;
}

.about .section-title,
.about .about-description {
    color: white;
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.about-description {
    font-size: 1.125rem;
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
    opacity: 0.9;
}

.about-cta {
    margin-top: var(--spacing-xl);
}

.about-stats {
    display: grid;
    gap: var(--spacing-md);
}

.about-stat-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: var(--spacing-xl);
    border-radius: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.2);
    text-align: center;
}

.about-stat-number {
    font-size: 3rem;
    font-weight: 800;
    color: var(--accent-500);
    margin-bottom: 0.5rem;
}

.about-stat-label {
    font-size: 1rem;
    opacity: 0.8;
}

/* ============================================
   CTA SECTION
   ============================================ */

.cta {
    padding: var(--spacing-3xl) 0;
    background: linear-gradient(135deg, var(--primary-500), var(--primary-700));
    color: white;
    text-align: center;
}

.cta-title {
    font-size: clamp(2rem, 4vw, 3rem);
    color: white;
    margin-bottom: var(--spacing-md);
}

.cta-description {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
}

.cta-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

.cta .btn-secondary {
    background: white;
    border-color: white;
}

/* ============================================
   FOOTER
   ============================================ */

.footer {
    background: var(--gray-900);
    color: white;
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-tagline {
    opacity: 0.7;
    margin-top: var(--spacing-sm);
}

.footer-column h4 {
    color: white;
    margin-bottom: var(--spacing-md);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-column a {
    display: block;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 0.5rem;
}

.footer-column a:hover {
    color: white;
    transform: translateX(4px);
}

.footer-bottom {
    text-align: center;
    opacity: 0.5;
    font-size: 0.875rem;
}

.footer-bottom p {
    margin-bottom: 0.5rem;
}

/* ============================================
   ANIMATIONS
   ============================================ */

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

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

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-stats {
        gap: var(--spacing-md);
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .cta-buttons {
        flex-direction: column;
    }
    
    .btn-large {
        width: 100%;
    }
}

@media (max-width: 480px) {
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   MOBILE NAV FIX - Added for toggle functionality
   ============================================ */

/* Make mobile menu work when toggled */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
        z-index: 999;
        max-height: calc(100vh - 60px);
        overflow-y: auto;
    }
    
    .nav-links.active {
        display: flex !important;
        animation: slideDown 0.3s ease;
    }
    
    .nav-link {
        padding: 0.75rem 0;
        font-size: 1.1rem;
        border-bottom: 1px solid var(--gray-100);
    }
    
    .nav-link:last-child {
        border-bottom: none;
    }
    
    /* Hamburger animation */
    .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);
    }
}