/* ============================================
   PERSONAL WEBSITE STYLESHEET
   A clean, modern design inspired by academic websites
   ============================================ */

/* ============================================
   CSS VARIABLES
   Change these to customize your site's colors and fonts
   ============================================ */
:root {
    /* Primary Colors - Change these to match your brand */
    --primary-color: #2c5f7c;      /* Main brand color */
    --primary-dark: #1e4156;       /* Darker shade for hover states */
    --primary-light: #4a8fb9;      /* Lighter shade for accents */
    
    /* Secondary Colors */
    --secondary-color: #e67e22;    /* Accent color for buttons/highlights */
    --secondary-dark: #d35400;     /* Darker accent */
    
    /* Neutral Colors */
    --text-primary: #2c3e50;       /* Main text color */
    --text-secondary: #7f8c8d;     /* Secondary text (descriptions, etc) */
    --background: #ffffff;         /* Page background */
    --background-alt: #f8f9fa;     /* Alternate background for sections */
    --border-color: #e0e0e0;       /* Borders and dividers */
    
    /* Fonts - Change these to your preferred fonts */
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-heading: 'Georgia', 'Times New Roman', serif;
    
    /* Spacing */
    --section-padding: 80px;
    --container-width: 1200px;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 20px rgba(0,0,0,0.1);
    
    /* Transitions */
    --transition: all 0.3s ease;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    color: var(--text-primary);
    line-height: 1.6;
    background-color: var(--background);
}

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

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

a:hover {
    color: var(--primary-dark);
}

/* ============================================
   NAVIGATION BAR
   ============================================ */
.navbar {
    background-color: var(--background);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

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

.nav-link {
    color: var(--text-primary);
    font-weight: 500;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

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

/* Mobile Menu Toggle */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

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

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 120px 2rem;
    text-align: center;
}

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

.hero-title {
    font-size: 3rem;
    font-family: var(--font-heading);
    margin-bottom: 1rem;
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    opacity: 0.9;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-description {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    opacity: 0.85;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.6s both;
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 5px;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
}

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

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

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

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

/* ============================================
   SECTION LAYOUTS
   ============================================ */
.section {
    padding: var(--section-padding) 2rem;
}

.section:nth-child(even) {
    background-color: var(--background-alt);
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
}

.section-title {
    font-size: 2.5rem;
    font-family: var(--font-heading);
    color: var(--primary-color);
    margin-bottom: 1rem;
    text-align: center;
}

.section-description {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 3rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: start;
}

.about-image img {
    border-radius: 10px;
    box-shadow: var(--shadow-lg);
    width: 100%;
    object-fit: cover;
}

.about-text p {
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
    line-height: 1.8;
}

.about-links {
    display: flex;
    gap: 1.5rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.social-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background-color: var(--background);
    border: 2px solid var(--border-color);
    border-radius: 5px;
    color: var(--text-primary);
    transition: var(--transition);
}

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

/* ============================================
   PROJECTS SECTION
   ============================================ */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.project-card {
    background-color: var(--background);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.project-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
    background-color: var(--background-alt);
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.project-card:hover .project-image img {
    transform: scale(1.05);
}

.project-content {
    padding: 1.5rem;
}

.project-title {
    font-size: 1.4rem;
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    font-family: var(--font-heading);
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.project-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.tag {
    background-color: var(--primary-light);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.85rem;
}

.project-link {
    color: var(--primary-color);
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.project-link:hover {
    gap: 0.75rem;
}

/* ============================================
   PUBLICATIONS SECTION
   ============================================ */
.publications-list {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    display: grid;
    grid-template-columns: 80px 1fr;
    gap: 2rem;
    padding: 2rem 0;
    border-bottom: 1px solid var(--border-color);
}

.publication-item:last-child {
    border-bottom: none;
}

.publication-year {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary-color);
}

.publication-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-family: var(--font-heading);
}

.publication-authors {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.publication-venue {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.publication-links {
    display: flex;
    gap: 1rem;
}

.pub-link {
    padding: 0.5rem 1rem;
    background-color: var(--background-alt);
    border-radius: 5px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: var(--transition);
}

.pub-link:hover {
    background-color: var(--primary-color);
    color: white;
}

/* ============================================
   CONTACT SECTION
   ============================================ */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 3rem;
    max-width: 1000px;
    margin: 0 auto;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.contact-item {
    display: flex;
    gap: 1rem;
    align-items: start;
}

.contact-item svg {
    color: var(--primary-color);
    flex-shrink: 0;
    margin-top: 0.25rem;
}

.contact-item h3 {
    font-size: 1.1rem;
    margin-bottom: 0.25rem;
    color: var(--primary-color);
}

.contact-item p,
.contact-item a {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Contact Form */
.contact-form {
    background-color: var(--background);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow-md);
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 5px;
    font-family: var(--font-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group textarea {
    resize: vertical;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background-color: var(--primary-dark);
    color: white;
    padding: 2rem;
    text-align: center;
}

.footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
}

.footer-links a {
    color: white;
    opacity: 0.8;
    transition: var(--transition);
}

.footer-links a:hover {
    opacity: 1;
}

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

/* ============================================
   RESPONSIVE DESIGN
   Automatically adjusts layout for different screen sizes
   ============================================ */

/* Tablet Screens */
@media (max-width: 968px) {
    :root {
        --section-padding: 60px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .about-image {
        max-width: 400px;
        margin: 0 auto;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .publication-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
}

/* Mobile Screens */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--background);
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active .bar:nth-child(1) {
        transform: translateY(9px) rotate(45deg);
    }
    
    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-9px) rotate(-45deg);
    }
    
    .hero {
        padding: 80px 2rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .footer .container {
        flex-direction: column;
        text-align: center;
    }
}

/* Small Mobile Screens */
@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    .nav-container {
        padding: 1rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
    }
    
    .about-links {
        flex-direction: column;
    }
    
    .social-link {
        width: 100%;
        justify-content: center;
    }
}