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

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --gray: #7f8c8d;
    --light-gray: #ecf0f1;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header and Navigation */
header {
    background-color: var(--white);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

nav .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
}

.logo {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 700;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

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

.nav-links a:hover {
    color: var(--secondary-color);
}

/* Hero Section */
#hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--white);
    padding: 6rem 0;
    text-align: center;
}

.hero-content h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.tagline {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 0.75rem 2rem;
    text-decoration: none;
    border-radius: 5px;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

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

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

/* Sections */
section {
    padding: var(--spacing-lg) 0;
}

section:nth-child(even) {
    background-color: var(--light-bg);
}

section h2 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    text-align: center;
}

/* About Section */
.about-content {
    max-width: 900px;
    margin: 0 auto;
}

.about-text p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    line-height: 1.8;
}

.interests {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--white);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.interests h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.interests ul {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 0.75rem;
}

.interests li {
    padding: 0.5rem;
    background-color: var(--light-gray);
    border-radius: 4px;
    padding-left: 1.5rem;
    position: relative;
}

.interests li::before {
    content: "▹";
    position: absolute;
    left: 0.5rem;
    color: var(--secondary-color);
    font-weight: bold;
}

/* Experience Timeline */
.timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    padding-left: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: var(--secondary-color);
}

.timeline-item {
    margin-bottom: var(--spacing-md);
    position: relative;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -2.5rem;
    top: 0.5rem;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--secondary-color);
    border: 3px solid var(--white);
}

.timeline-year {
    color: var(--secondary-color);
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.timeline-content h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.timeline-content p {
    color: var(--gray);
}

/* Projects Grid */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.project-card {
    background-color: var(--white);
    padding: var(--spacing-md);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 20px rgba(0,0,0,0.15);
}

.project-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.project-card p {
    color: var(--gray);
    margin-bottom: 1rem;
    flex-grow: 1;
}

.tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tech-tags span {
    background-color: var(--light-gray);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 500;
}

/* Teaching Section */
.teaching-content {
    max-width: 900px;
    margin: 0 auto;
}

.course {
    background-color: var(--white);
    padding: var(--spacing-md);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.course h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.course h4 {
    color: var(--secondary-color);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.course p {
    margin-bottom: 1rem;
    line-height: 1.8;
}

.course ul {
    margin-left: 2rem;
    margin-bottom: 1rem;
}

.course li {
    margin-bottom: 0.5rem;
}

.teaching-philosophy {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--light-bg);
    border-left: 4px solid var(--secondary-color);
    border-radius: 4px;
}

.teaching-philosophy h4 {
    margin-top: 0;
}

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

.contact-content > p {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-md);
}

.contact-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.contact-item {
    background-color: var(--white);
    padding: var(--spacing-md);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.contact-item h3 {
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.contact-item a {
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
}

.contact-item a:hover {
    text-decoration: underline;
}

/* Footer */
footer {
    background-color: var(--primary-color);
    color: var(--white);
    text-align: center;
    padding: 2rem 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    nav .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
    
    .hero-content h2 {
        font-size: 2rem;
    }
    
    .tagline {
        font-size: 1.1rem;
    }
    
    section h2 {
        font-size: 1.75rem;
    }
    
    .timeline {
        padding-left: 1.5rem;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .hero-content h2 {
        font-size: 1.5rem;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .interests ul {
        grid-template-columns: 1fr;
    }
}