:root {
    --primary-color: #1877F2;
    --primary-dark: #166FE5;
    --secondary-color: #42B72A;
    --accent-color: #E7F3FF;
    --background-color: #F0F2F5;
    --text-color: #050505;
    --card-background: #FFFFFF;
    --border-color: #E4E6EB;
    --light-text: #65676B;
    --footer-bg: #F0F2F5;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

.skip-to-content {
    position: absolute;
    left: -9999px;
    top: auto;
    width: 1px;
    height: 1px;
    overflow: hidden;
}

.skip-to-content:focus {
    position: fixed;
    top: 0;
    left: 0;
    width: auto;
    height: auto;
    padding: 10px 15px;
    background: var(--primary-color);
    color: white;
    z-index: 9999;
    font-weight: 600;
    text-decoration: none;
}

/* Navbar styles */
.navbar {
    background-color: var(--card-background);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 15px 0;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

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

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary-color);
    text-decoration: none;
}

.project-tag {
    font-size: 0.9rem;
    background-color: var(--accent-color);
    color: var(--primary-color);
    padding: 4px 8px;
    border-radius: 4px;
    margin-left: 10px;
    font-weight: 500;
}

.nav-links {
    display: flex;
    gap: 20px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.2s;
}

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

.auth-buttons {
    display: flex;
    gap: 12px;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s ease;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

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

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

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

.btn-secondary:hover {
    background-color: #36A420;
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 1px solid var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--accent-color);
}

/* Hero section */
.hero {
    padding: 80px 0;
    text-align: center;
    background: linear-gradient(135deg, var(--accent-color) 0%, var(--background-color) 100%);
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 20px;
    color: var(--text-color);
    line-height: 1.2;
}

.course-info {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 10px 15px;
    border-radius: 4px;
    margin-bottom: 15px;
    font-weight: 500;
}

.project-title {
    font-size: 1.4rem;
    font-weight: 500;
    margin-bottom: 25px;
    color: var(--primary-dark);
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    color: var(--light-text);
}

/* Features section */
.features {
    padding: 80px 0;
    background-color: var(--card-background);
}

.section-title {
    text-align: center;
    margin-bottom: 60px;
}

.section-title h2 {
    font-size: 2.2rem;
    color: var(--text-color);
    margin-bottom: 15px;
}

.section-title p {
    color: var(--light-text);
    max-width: 600px;
    margin: 0 auto;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.feature-card {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 30px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.feature-card h3 {
    font-size: 1.4rem;
    margin-bottom: 15px;
    color: var(--text-color);
}

.feature-card p {
    color: var(--light-text);
}

/* Tech stack section */
.tech-stack {
    padding: 80px 0;
    background-color: var(--background-color);
}

.tech-cards {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
    margin-top: 40px;
}

.tech-card {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    padding: 20px;
    width: 180px;
    text-align: center;
    transition: transform 0.3s ease;
}

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

.tech-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 15px;
}

.tech-card h3 {
    font-size: 1.1rem;
    margin-bottom: 10px;
}

.tech-card p {
    font-size: 0.9rem;
    color: var(--light-text);
}

/* How it works section */
.how-it-works {
    padding: 80px 0;
    background-color: var(--card-background);
}

.knn-explanation {
    background-color: var(--accent-color);
    border-radius: 8px;
    padding: 30px;
    margin-top: 40px;
}

.knn-explanation h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.4rem;
}

.knn-explanation p {
    margin-bottom: 15px;
}

.knn-explanation ul {
    margin-left: 20px;
    margin-bottom: 15px;
}

.knn-explanation li {
    margin-bottom: 8px;
}

.algorithm-highlight {
    background-color: var(--card-background);
    border-radius: 6px;
    padding: 20px;
    margin-top: 20px;
}

.algorithm-highlight h4 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

/* Project docs section */
.project-docs {
    padding: 80px 0;
    background-color: var(--background-color);
}

.docs-container {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    padding: 40px;
    margin-top: 40px;
}

.docs-header {
    text-align: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.docs-header h3 {
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.docs-header p {
    color: var(--light-text);
}

.docs-content h4 {
    font-size: 1.4rem;
    margin: 25px 0 15px;
    color: var(--primary-color);
}

.docs-content h5 {
    font-size: 1.1rem;
    margin: 20px 0 10px;
}

.docs-content p {
    margin-bottom: 15px;
}

.docs-content ul {
    margin-left: 20px;
    margin-bottom: 20px;
}

.docs-content li {
    margin-bottom: 8px;
}

/* Footer */
.footer {
    background-color: var(--footer-bg);
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
}

.footer-logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 15px;
    display: block;
}

.footer-description {
    color: var(--light-text);
    margin-bottom: 20px;
}

.footer-links h4 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: var(--text-color);
}

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

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    text-decoration: none;
    color: var(--light-text);
    transition: color 0.2s;
}

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

.social-links {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

.social-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: var(--card-background);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

.social-icon:hover {
    background-color: var(--primary-color);
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    margin-top: 30px;
    border-top: 1px solid var(--border-color);
    color: var(--light-text);
    font-size: 0.9rem;
}

/* Premium badge */
.premium-badge {
    position: absolute;
    top: 10px;
    right: 10px;
    background: linear-gradient(135deg, #FFD700 0%, #FFA500 100%);
    color: #000;
    padding: 5px 12px;
    border-radius: 20px;
    font-weight: 700;
    font-size: 0.8rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    z-index: 10;
}

/* Mobile responsiveness */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.2rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .nav-links {
        display: none;
    }

    .auth-buttons {
        gap: 8px;
    }

    .btn {
        padding: 8px 16px;
        font-size: 0.9rem;
    }

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

    .docs-container {
        padding: 20px;
    }
}