/* Base Styles and Variables */
:root {
    /* Light Theme Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9f9fc;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --accent-primary: #3b82f6;
    --accent-secondary: #a3bffa;
    --border-color: #e2e8f0;
    --card-bg: #ffffff;
    --card-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
    --gradient-start: #3b82f6;
    --gradient-end: #4f46e5;
    
    /* Transitions */
    --transition: all 0.3s ease;
    
    /* Spacing */
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --font-size-sm: 0.875rem;
    --font-size-md: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
}

/* Dark Theme Colors (will be applied with JS) */
.dark-theme {
    --bg-primary: #121826;
    --bg-secondary: #1b2336;
    --text-primary: #f0f4f8;
    --text-secondary: #cbd5e0;
    --accent-primary: #60a5fa;
    --accent-secondary: #4c51bf;
    --border-color: #2d3748;
    --card-bg: #1e293b;
    --card-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --gradient-start: #60a5fa;
    --gradient-end: #7c3aed;
}

/* Reset & Base Elements */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

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

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    letter-spacing: -0.025em;
}

h2 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
}

h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-secondary);
}

h5 {
    font-size: var(--font-size-md);
    font-weight: 600;
    color: var(--text-secondary);
}

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

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

a:hover {
    text-decoration: underline;
}

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

ul, ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

/* Layout */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

section {
    padding: var(--spacing-xl) 0;
}

/* Header & Navigation */
header {
    position: sticky;
    top: 0;
    background-color: var(--bg-primary);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    z-index: 100;
    transition: var(--transition);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
    padding: 0 var(--spacing-lg);
}

.logo {
    font-size: var(--font-size-xl);
    font-weight: 800;
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    cursor: pointer;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

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

.nav-links a:hover {
    text-decoration: none;
    color: var(--accent-primary);
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    transition: var(--transition);
}

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

.theme-toggle {
    cursor: pointer;
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    transition: var(--transition);
}

.theme-toggle:hover {
    color: var(--accent-primary);
    transform: rotate(15deg);
}

/* Hero Section */
#hero {
    min-height: calc(100vh - 70px);
    display: flex;
    align-items: center;
    background-color: var(--bg-secondary);
    padding: var(--spacing-xl) 0;
    position: relative;
    overflow: hidden;
}

#hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at top right, var(--accent-secondary) 0%, transparent 70%);
    opacity: 0.1;
    z-index: 0;
}

.hero-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-xl);
    position: relative;
    z-index: 1;
}

.hero-text {
    flex: 1;
}

.hero-text h1 {
    margin-bottom: var(--spacing-sm);
}

.hero-text h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    color: var(--accent-primary);
}

.hero-text p {
    font-size: var(--font-size-lg);
    max-width: 600px;
    margin-bottom: var(--spacing-lg);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    border-radius: var(--radius-full);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: var(--font-size-lg);
    transition: var(--transition);
    box-shadow: var(--card-shadow);
}

.social-links a:hover {
    transform: translateY(-3px);
    background-color: var(--accent-primary);
    color: white;
}

.hero-image {
    flex: 0 0 300px;
}

#profile-photo {
    border-radius: var(--radius-lg);
    box-shadow: var(--card-shadow);
    border: 4px solid var(--bg-primary);
    transition: var(--transition);
    filter: grayscale(20%);
}

#profile-photo:hover {
    filter: grayscale(0%);
    transform: scale(1.02);
}

/* Section Styling */
.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    border-radius: var(--radius-full);
}

/* About Section */
.about-content {
    max-width: 800px;
    margin: 0 auto;
}

/* Research Interests */
.research-interests {
    margin: var(--spacing-lg) 0;
}

.research-interests h3 {
    margin-bottom: var(--spacing-md);
    text-align: center;
    color: var(--text-primary);
}

.interests-container {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin: var(--spacing-md) 0;
    flex-wrap: wrap;
}

.interest-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    background-color: var(--bg-secondary);
    border-radius: var(--radius-md);
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    width: 220px;
}

.interest-item i {
    font-size: 2rem;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-sm);
}

.interest-item span {
    font-weight: 500;
    color: var(--text-primary);
}

.interest-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

/* Funding Logos Section */
.funding-section {
    margin: var(--spacing-xl) 0;
}

.funding-section h3 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.funding-logos {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-xl);
    margin-top: var(--spacing-lg);
}

.funding-logo {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    box-shadow: var(--card-shadow);
    transition: var(--transition);
}

.funding-logo:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
}

/* Memberships Section */
#memberships {
    background-color: var(--bg-secondary);
    padding: var(--spacing-xl) 0;
}

.membership-content {
    display: flex;
    justify-content: center;
    align-items: center;
    max-width: 800px;
    margin: 0 auto;
}

.memberships-list {
    list-style: none;
    padding: 0;
    width: 100%;
    max-width: 800px;
}

.memberships-list li {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--card-bg);
    border-radius: var(--radius-md);
    box-shadow: var(--card-shadow);
    margin-bottom: var(--spacing-md);
    transition: var(--transition);
}

.memberships-list li:hover {
    transform: translateX(5px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
}

.memberships-list li i {
    font-size: var(--font-size-xl);
    color: var(--accent-primary);
    min-width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-secondary);
    border-radius: var(--radius-full);
}

.memberships-list li span {
    font-weight: 500;
    color: var(--text-primary);
}

/* Publications Section */
.publications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.publication-card {
    background-color: var(--card-bg);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--card-shadow);
    border-top: 4px solid var(--accent-primary);
    transition: var(--transition);
    height: 100%;
    display: flex;
    flex-direction: column;
}

.publication-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

.publication-card h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.publication-authors {
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.publication-venue {
    font-weight: 600;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-md);
}

.publication-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    margin-top: auto;
}

.publication-link {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    font-size: var(--font-size-sm);
    padding: 5px 10px;
    border-radius: var(--radius-sm);
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    transition: var(--transition);
}

/* Portfolio Section */
.portfolio-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.portfolio-card {
    background-color: var(--card-bg);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    height: 100%;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.portfolio-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
}

.portfolio-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

.portfolio-card-header {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 60px;
    height: 60px;
    border-radius: var(--radius-full);
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    margin-bottom: var(--spacing-md);
    color: white;
    font-size: 1.5rem;
}

.portfolio-card h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.portfolio-description {
    color: var(--text-secondary);
    margin-bottom: auto;
    padding-bottom: var(--spacing-md);
}

.portfolio-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.portfolio-tech span {
    font-size: var(--font-size-sm);
    padding: 3px 8px;
    border-radius: var(--radius-sm);
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    font-weight: 500;
}

.portfolio-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.portfolio-link {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    font-size: var(--font-size-sm);
    padding: 7px 12px;
    border-radius: var(--radius-sm);
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    transition: var(--transition);
    text-decoration: none;
}

.portfolio-link:hover {
    background-color: var(--accent-primary);
    color: white;
    text-decoration: none;
}

/* Experience Section */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    left: 15px;
    height: 100%;
    width: 2px;
    background: linear-gradient(to bottom, var(--gradient-start), var(--gradient-end));
}

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

.timeline-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 6px;
    width: 30px;
    height: 30px;
    border-radius: var(--radius-full);
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    box-shadow: 0 0 0 4px var(--bg-primary);
    z-index: 1;
}

.timeline-date {
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    color: var(--accent-primary);
}

.timeline-content {
    background-color: var(--card-bg);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--card-shadow);
    transition: var(--transition);
}

.timeline-content:hover {
    transform: translateX(5px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
}

/* Sub-roles Section */
.sub-roles {
    margin-top: var(--spacing-lg);
    border-top: 1px dashed var(--border-color);
    padding-top: var(--spacing-lg);
}

.sub-role {
    background-color: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
    border-left: 3px solid var(--accent-primary);
}

.sub-role:hover {
    transform: translateX(5px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.sub-role h4 {
    font-size: calc(var(--font-size-md) + 0.1rem);
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.sub-role h5 {
    font-size: var(--font-size-md);
    margin-bottom: var(--spacing-sm);
    color: var(--accent-primary);
}

.sub-role-date {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    font-style: italic;
}

.sub-role p {
    font-size: var(--font-size-md);
    margin-bottom: 0;
}

/* Contact Section */
.contact-content {
    max-width: 600px;
    margin: 0 auto;
    background-color: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--card-shadow);
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.contact-item i {
    font-size: var(--font-size-xl);
    color: var(--accent-primary);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-secondary);
    border-radius: var(--radius-full);
}

/* Footer */
footer {
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    padding: var(--spacing-lg) 0;
    text-align: center;
    margin-top: var(--spacing-xl);
}

.footer-note {
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-md);
}

/* Responsive Design */
@media (max-width: 960px) {
    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
    }
    
    .hero-text p {
        margin: 0 auto var(--spacing-lg);
    }
    
    .social-links {
        justify-content: center;
    }
    
    .hero-image {
        margin-bottom: var(--spacing-lg);
    }
    
    .publications-grid {
        grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    }
    
    .interests-container {
        flex-direction: column;
        align-items: center;
    }
    
    .interest-item {
        width: 100%;
        max-width: 300px;
    }
    
    .memberships-list li {
        flex-direction: column;
        text-align: center;
        padding: var(--spacing-lg);
    }
    
    .memberships-list li i {
        margin-bottom: var(--spacing-sm);
    }
    
    .funding-logos {
        gap: var(--spacing-md);
    }
}

@media (max-width: 768px) {
    nav {
        padding: 0 var(--spacing-md);
    }
    
    .nav-links {
        gap: var(--spacing-md);
    }
    
    .hero-text h1 {
        font-size: var(--font-size-2xl);
    }
    
    .hero-text h2 {
        font-size: var(--font-size-lg);
    }
    
    .publications-grid {
        grid-template-columns: 1fr;
    }
    
    .portfolio-grid {
        grid-template-columns: 1fr;
    }
    
    .timeline::before {
        left: 12px;
    }
    
    .timeline-item::before {
        width: 24px;
        height: 24px;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    .nav-links {
        display: none;
    }
    
    .timeline-item {
        padding-left: var(--spacing-lg);
    }
    
    .sub-role {
        padding: var(--spacing-sm);
    }
}