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

:root {
    /* Black and Blue Color Scheme */
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #1e293b;
    --secondary-dark: #0f172a;
    --accent-color: #60a5fa;
    --error-color: #ef4444;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    
    /* Dark Theme */
    --black: #0f172a;
    --black-light: #1e293b;
    --black-medium: #334155;
    --black-soft: #475569;
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    
    /* Glassmorphism Colors */
    --glass-black: rgba(0, 0, 0, 0.3);
    --glass-black-strong: rgba(0, 0, 0, 0.5);
    --glass-black-light: rgba(0, 0, 0, 0.2);
    --glass-white: rgba(255, 255, 255, 0.1);
    --glass-white-strong: rgba(255, 255, 255, 0.15);
    --glass-blue: rgba(37, 99, 235, 0.1);
    --glass-blue-strong: rgba(37, 99, 235, 0.2);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;
    
    /* Glassmorphism 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 -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --shadow-glass: 0 8px 32px 0 rgba(31, 38, 135, 0.37);
    --shadow-glass-light: 0 4px 16px 0 rgba(31, 38, 135, 0.2);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    
    /* Backdrop blur values */
    --blur-sm: blur(4px);
    --blur-md: blur(8px);
    --blur-lg: blur(16px);
    --blur-xl: blur(24px);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--white);
    background: var(--black);
    min-height: 100vh;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 50%, rgba(37, 99, 235, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(37, 99, 235, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 50% 80%, rgba(37, 99, 235, 0.03) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-2) var(--spacing-4);
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-xl);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    backdrop-filter: var(--blur-sm);
    border: 1px solid rgba(255, 255, 255, 0.2);
    position: relative;
    overflow: hidden;
    color: rgba(255, 255, 255, 1) !important;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

.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-large {
    padding: var(--spacing-3) var(--spacing-6);
    font-size: var(--font-size-base);
}

.btn-primary {
    background: var(--primary-color);
    color: rgba(255, 255, 255, 1) !important;
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
    font-weight: 600;
}

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

.btn-secondary {
    background-color: var(--gray-600);
    color: white;
}

.btn-secondary:hover {
    background-color: var(--gray-700);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: rgba(0, 0, 0, 0.6);
    color: rgba(255, 255, 255, 1) !important;
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(12px) saturate(150%);
    font-weight: 500;
}

.btn-outline:hover {
    background: rgba(0, 0, 0, 0.8);
    color: rgba(255, 255, 255, 1);
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
    border-color: rgba(37, 99, 235, 0.6);
}

/* Navigation */
.navbar {
    background: var(--glass-black);
    backdrop-filter: var(--blur-lg);
    border-bottom: 1px solid var(--gray-700);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    box-shadow: var(--shadow-md);
}

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

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

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

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-8);
}

.nav-link {
    color: var(--gray-300);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-fast);
}

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

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

.bar {
    width: 25px;
    height: 3px;
    background-color: var(--white);
    margin: 3px 0;
    transition: var(--transition-fast);
}

/* Hero Section */
.hero {
    padding: 8rem 0 6rem;
    position: relative;
    overflow: hidden;
    background: transparent;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 50%;
    height: 100%;
    background: radial-gradient(circle at center, var(--glass-primary) 0%, transparent 70%);
    z-index: 1;
}

.hero-container {
    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-title {
    font-size: var(--font-size-5xl);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-6);
    color: var(--white);
}

.highlight {
    color: var(--primary-color);
    position: relative;
}

.highlight::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 0.5rem;
    background: linear-gradient(90deg, var(--primary-light) 0%, var(--secondary-color) 100%);
    opacity: 0.3;
    z-index: -1;
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--gray-300);
    margin-bottom: var(--spacing-8);
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-12);
}

.hero-stats {
    display: flex;
    gap: var(--spacing-8);
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--gray-300);
}

/* Hero Visual */
.hero-visual {
    position: relative;
}

.demo-preview {
    background: var(--white);
    backdrop-filter: var(--blur-md);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-6);
    box-shadow: var(--shadow-xl);
    transform: rotate(2deg);
    transition: transform var(--transition-slow);
}

.demo-preview:hover {
    transform: rotate(0deg) scale(1.02);
}

.worksheet-stack {
    position: relative;
    margin-bottom: var(--spacing-4);
}

.worksheet {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: var(--spacing-4);
    position: relative;
    margin-bottom: var(--spacing-2);
    box-shadow: var(--shadow-sm);
}

.worksheet-1 {
    z-index: 3;
    transform: translateY(0);
}

.worksheet-2 {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 2;
    transform: translateY(8px) translateX(8px);
    opacity: 0.8;
}

.worksheet-3 {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1;
    transform: translateY(16px) translateX(16px);
    opacity: 0.6;
}

.worksheet-header {
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: var(--spacing-3);
    border-bottom: 1px solid var(--gray-200);
    padding-bottom: var(--spacing-2);
}

.problem {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    margin-bottom: var(--spacing-2);
    font-family: 'Courier New', monospace;
}

.answer.correct {
    color: var(--success-color);
    font-weight: 600;
}

.answer.incorrect {
    color: var(--error-color);
    font-weight: 600;
    text-decoration: line-through;
}

.problem i.fa-check-circle {
    color: var(--success-color);
}

.problem i.fa-times-circle {
    color: var(--error-color);
}

.feedback-bubble {
    background: var(--primary-color);
    color: white;
    padding: var(--spacing-3);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-4);
    position: relative;
}

.feedback-bubble::before {
    content: '';
    position: absolute;
    top: -8px;
    left: var(--spacing-4);
    width: 0;
    height: 0;
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-bottom: 8px solid var(--primary-color);
}

.grading-progress {
    text-align: center;
}

.progress-bar {
    background: var(--gray-200);
    border-radius: var(--radius-lg);
    height: 8px;
    overflow: hidden;
    margin-bottom: var(--spacing-2);
}

.progress-fill {
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    height: 100%;
    width: 75%;
    border-radius: var(--radius-lg);
    animation: progress 3s ease-in-out infinite;
}

@keyframes progress {
    0% { width: 0%; }
    50% { width: 75%; }
    100% { width: 100%; }
}

.progress-text {
    font-size: var(--font-size-sm);
    color: var(--gray-600);
}

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

.section-header h2 {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-4);
    color: var(--white);
}

.section-header p {
    font-size: var(--font-size-xl);
    color: var(--gray-300);
    max-width: 600px;
    margin: 0 auto;
}

/* Features Section */
.features {
    padding: 6rem 0;
    background: transparent;
}

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

.feature-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-8);
    text-align: center;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-color);
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    background: var(--gray-50);
}

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

.feature-icon {
    width: 80px;
    height: 80px;
    background: var(--gray-800);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-6);
    color: var(--white);
    font-size: var(--font-size-2xl);
    box-shadow: var(--shadow-md);
}

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

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

.feature-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-size: var(--font-size-sm);
    color: var(--gray-600);
}

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

/* How It Works Section */
.how-it-works {
    padding: 6rem 0;
    background: transparent;
    position: relative;
}

.how-it-works::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gray-50);
    z-index: -1;
}

.workflow-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-8);
    position: relative;
}

.workflow-steps::before {
    content: '';
    position: absolute;
    top: 50px;
    left: 10%;
    right: 10%;
    height: 2px;
    background: var(--gray-400);
    z-index: 1;
}

.step {
    text-align: center;
    position: relative;
    z-index: 2;
}

.step-number {
    width: 60px;
    height: 60px;
    background: var(--gray-900);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin: 0 auto var(--spacing-4);
    box-shadow: var(--shadow-lg);
}

.step-content h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-3);
    color: var(--gray-900);
}

.step-content p {
    color: var(--gray-600);
    line-height: 1.6;
    margin-bottom: var(--spacing-4);
}

.step-icon {
    color: var(--primary-color);
    font-size: var(--font-size-2xl);
}

/* Pricing Section */
.pricing {
    padding: 6rem 0;
    background: transparent;
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-8);
    max-width: 1000px;
    margin: 0 auto;
}

.pricing-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-8);
    text-align: center;
    position: relative;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
}

.pricing-card.featured {
    background: var(--gray-50);
    border: 2px solid var(--primary-color);
    transform: scale(1.05);
    box-shadow: var(--shadow-xl);
}

.pricing-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    background: var(--gray-50);
}

.pricing-card.featured:hover {
    transform: scale(1.05) translateY(-4px);
}

.pricing-badge {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--primary-color);
    color: white;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    font-weight: 600;
}

.pricing-header h3 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-4);
    color: var(--gray-900);
}

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

.price-amount {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--primary-color);
}

.price-period {
    font-size: var(--font-size-lg);
    color: var(--gray-500);
}

.pricing-features {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-3);
    margin-bottom: var(--spacing-8);
}

.pricing-features .feature {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    font-size: var(--font-size-base);
    color: var(--gray-700);
}

.pricing-features .feature i {
    color: var(--success-color);
    font-size: var(--font-size-sm);
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 3fr;
    gap: var(--spacing-16);
    margin-bottom: var(--spacing-12);
}

.footer-brand .nav-brand {
    color: white;
    margin-bottom: var(--spacing-4);
}

.footer-brand p {
    line-height: 1.6;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-8);
}

.footer-column h4 {
    color: white;
    font-weight: 600;
    margin-bottom: var(--spacing-4);
}

.footer-column a {
    display: block;
    color: var(--gray-400);
    text-decoration: none;
    margin-bottom: var(--spacing-2);
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-8);
    border-top: 1px solid var(--gray-700);
}

.social-links {
    display: flex;
    gap: var(--spacing-4);
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--gray-800);
    color: var(--gray-400);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    transition: all var(--transition-fast);
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 4rem;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: var(--spacing-8) 0;
        gap: var(--spacing-4);
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active .bar:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active .bar:nth-child(1) {
        transform: translateY(6px) rotate(45deg);
    }

    .nav-toggle.active .bar:nth-child(3) {
        transform: translateY(-6px) rotate(-45deg);
    }

    .hero-container {
        grid-template-columns: 1fr;
        gap: var(--spacing-8);
        text-align: center;
    }

    .hero-title {
        font-size: var(--font-size-3xl);
    }

    .hero-actions {
        flex-direction: column;
        align-items: center;
    }

    .hero-stats {
        justify-content: center;
        gap: var(--spacing-6);
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .workflow-steps {
        grid-template-columns: 1fr;
    }

    .workflow-steps::before {
        display: none;
    }

    .pricing-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-8);
    }

    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-4);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-3);
    }

    .hero {
        padding: 6rem 0 4rem;
    }

    .hero-title {
        font-size: var(--font-size-2xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-lg);
    }

    .section-header h2 {
        font-size: var(--font-size-3xl);
    }

    .section-header p {
        font-size: var(--font-size-lg);
    }

    .footer-links {
        grid-template-columns: 1fr;
    }
}