/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Light theme variables */
    --primary-color: #4a76a8;
    --primary-hover: #3a6590;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    
    --border-color: #dee2e6;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.15);
    
    --border-radius: 8px;
    --border-radius-lg: 12px;
    
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-size-base: 16px;
    --line-height: 1.6;
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3d3d3d;
    
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --text-muted: #666666;
    
    --border-color: #404040;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.4);
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: all 0.3s ease;
}

.grow{
    flex-grow: 1;
}

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

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    padding: 1rem 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-color);
}

.nav {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: all 0.3s ease;
}

/* Buttons */
.cta-button {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

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

.cta-button.primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.cta-button.secondary {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.cta-button.secondary:hover {
    background: var(--primary-color);
    color: white;
}

.cta-button.large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.cta-button.full-width {
    width: 100%;
}

/* Hero Section */
.hero {
    padding: 120px 0 80px;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-text h1 {
    font-size: 3.5rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
}

.hero-visual {
    display: flex;
    justify-content: center;
}

.chat-demo {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-lg);
    max-width: 400px;
    width: 100%;
}

.message {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1rem;
    align-items: flex-start;
}

.message.user {
    justify-content: flex-end;
}

.message.user .content {
    background: var(--primary-color);
    color: white;
    border-radius: 18px 18px 4px 18px;
}

.message.assistant .content {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border-radius: 18px 18px 18px 4px;
}

.message .content {
    padding: 0.75rem 1rem;
    max-width: 70%;
}

.avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    font-size: 0.875rem;
}

.message.typing .content::after {
    content: '...';
    animation: typing 1.5s infinite;
}

@keyframes typing {
    0%, 20% { content: '.'; }
    40% { content: '..'; }
    60%, 100% { content: '...'; }
}

/* Sections */
section {
    padding: 80px 0;
}

h2 {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

/* Features */
.features-grid {
    display: flex;
    gap: 2rem;
    flex-direction: row;
    justify-content: space-between;
    align-items: stretch;
    flex-wrap: wrap;
}

.feature-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    text-align: center;
    transition: transform 0.3s ease;
    width: calc(50% - 2rem);
}

.feature-card:hover {
    transform: translateY(-5px);
}

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

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* How it works */
.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 3rem;
    text-align: center;
}

.step {
    position: relative;
}

.step-number {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin: 0 auto 1.5rem;
}

.step h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.step p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* CTA Section */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    color: white;
    text-align: center;
    padding: 100px 0;
}

.cta-section h2 {
    color: white;
    margin-bottom: 1rem;
}

.cta-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    opacity: 0.9;
}

/* FAQ */
.faq-items {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
}

.faq-question {
    width: 100%;
    padding: 1.5rem 0;
    background: none;
    border: none;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

.faq-question:hover {
    color: var(--primary-color);
}

.faq-icon {
    font-size: 1.5rem;
    transition: transform 0.3s ease;
}

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

.faq-item.active .faq-answer {
    max-height: 200px;
}

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

.faq-answer p {
    padding: 0 0 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-column h4 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.footer-column a {
    display: block;
    color: var(--text-secondary);
    text-decoration: none;
    margin-bottom: 0.5rem;
    transition: color 0.3s ease;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
}

.modal-content {
    background: var(--bg-primary);
    margin: 5% auto;
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    max-width: 400px;
    width: 90%;
    position: relative;
    box-shadow: var(--shadow-lg);
}

.close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-muted);
}

.close:hover {
    color: var(--text-primary);
}

/* Auth Tabs */
.auth-tabs {
    display: flex;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.tab {
    flex: 1;
    padding: 1rem;
    background: none;
    border: none;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-muted);
    border-bottom: 2px solid transparent;
}

.tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.auth-form {
    display: none;
}

.auth-form.active {
    display: block;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 118, 168, 0.1);
}

.auth-divider {
    text-align: center;
    margin: 1.5rem 0;
    position: relative;
}

.auth-divider::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    height: 1px;
    background: var(--border-color);
}

.auth-divider span {
    background: var(--bg-primary);
    padding: 0 1rem;
    position: relative;
    color: var(--text-muted);
}

.oauth-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.oauth-button {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--bg-primary);
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.oauth-button:hover {
    background: var(--bg-secondary);
    transform: translateY(-1px);
}

.oauth-button.google {
    color: #DB4437;
}

.oauth-button.yandex {
    color: #FFCC00;
}

.auth-link {
    display: block;
    text-align: center;
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9rem;
}

.auth-link:hover {
    text-decoration: underline;
}

h3 sup{
    font-weight: normal;
    font-size: .9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }
    
    .hero-text h1 {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-primary);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow);
    }
    
    .nav.active {
        display: flex;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .steps,
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .feature-card{
        width: 100%;
    }

    section {
        padding: 60px 0;
    }
    
    h2 {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-text h1 {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .cta-button.large {
        padding: 0.875rem 1.5rem;
        font-size: 1rem;
    }
    
    .modal-content {
        margin: 10% auto;
        width: 95%;
        padding: 1.5rem;
    }
}

/* Dark theme support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #1a1a1a;
        --bg-secondary: #2d2d2d;
        --bg-tertiary: #3d3d3d;
        --text-primary: #ffffff;
        --text-secondary: #b3b3b3;
        --text-muted: #666666;
        --border-color: #404040;
        --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.4);
    }
    
    .header {
        background: rgba(26, 26, 26, 0.95);
    }
    
    .chat-demo {
        background: var(--bg-tertiary);
    }
}