/* ===================================
   Simple Academic Portfolio - 3 Colors Only
   =================================== */

:root {
    /* Academic 3-Color Palette */
    --primary-color: #2563eb;     /* Professional Blue - links & accents */
    --text-color: #1f2937;         /* Dark Gray - text */
    --bg-color: #ffffff;           /* White - backgrounds */
    
    /* Typography */
    --font-heading: Georgia, serif;
    --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --max-width: 1100px;
}

/* Dark Mode - 3 Colors */
body.dark-mode {
    --primary-color: #60a5fa;      /* Light Blue */
    --text-color: #e5e7eb;         /* Light Gray */
    --bg-color: #1f2937;           /* Dark Gray */
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    color: var(--text-color);
    line-height: 1.7;
    background-color: var(--bg-color);
    transition: all 0.3s ease;
}

/* Dark Mode Toggle */
.dark-mode-toggle {
    background: var(--bg-color);
    border: 1px solid var(--text-color);
    padding: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    transition: all 0.3s ease;
}

.dark-mode-toggle:hover {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.dark-mode-toggle:hover svg {
    stroke: var(--bg-color);
}

.dark-mode-toggle svg {
    width: 20px;
    height: 20px;
    stroke: var(--text-color);
    transition: all 0.3s ease;
}

.dark-mode-toggle .moon-icon {
    display: none;
}

body.dark-mode .dark-mode-toggle .sun-icon {
    display: none;
}

body.dark-mode .dark-mode-toggle .moon-icon {
    display: block;
}

/* Navigation */
.navbar {
    background: var(--bg-color);
    padding: 1rem 2rem;
    border-bottom: 1px solid var(--text-color);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

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

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-color);
    text-decoration: none;
    font-family: var(--font-heading);
}

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

.nav-menu li {
    display: flex;
    align-items: center;
}

.nav-link {
    color: var(--text-color);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.3s ease;
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 25px;
    height: 2px;
    background: var(--text-color);
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: var(--bg-color);
    padding: 6rem 2rem 4rem;
    border-bottom: 1px solid var(--text-color);
}

.hero-container {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 400;
    color: var(--text-color);
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.hero-subtitle {
    font-size: 1.125rem;
    color: var(--text-color);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1rem;
    color: var(--text-color);
    line-height: 1.7;
    margin-bottom: 2rem;
}

.hero-image img {
    width: 100%;
    max-width: 300px;
    border-radius: 50%;
    border: 2px solid var(--text-color);
}

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

.hero-btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background: var(--bg-color);
    color: var(--primary-color);
    text-decoration: none;
    transition: all 0.3s ease;
    border: 1px solid var(--primary-color);
}

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

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

.hero-btn-primary:hover {
    opacity: 0.85;
}

/* Sections */
.section {
    padding: 4rem 2rem;
    background: var(--bg-color);
    border-bottom: 1px solid var(--text-color);
}

.section-dark {
    background: var(--text-color);
    color: var(--bg-color);
    border-bottom: none;
}

body.dark-mode .section-dark {
    background: var(--bg-color);
    color: var(--text-color);
    border-top: 1px solid var(--text-color);
    border-bottom: 1px solid var(--text-color);
}

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

.section-title {
    font-family: var(--font-heading);
    font-size: 2rem;
    color: var(--text-color);
    margin-bottom: 3rem;
    text-align: center;
    font-weight: 400;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 2px;
    background: var(--primary-color);
    margin: 0.75rem auto 0;
}

.section-dark .section-title {
    color: var(--bg-color);
}

body.dark-mode .section-dark .section-title {
    color: var(--text-color);
}

body.dark-mode .section-dark .section-title::after {
    background: var(--primary-color);
}

/* Grids */
.about-grid,
.teaching-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.publications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 2rem;
}

.experience-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

/* Cards */
.about-card,
.contact-card,
.research-card,
.experience-card,
.editorial-section {
    background: var(--bg-color);
    padding: 2rem;
    border: 1px solid var(--text-color);
}

.about-card h3,
.contact-card h3,
.research-card h3,
.experience-card h3,
.editorial-section h3 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    color: var(--text-color);
    margin-bottom: 1rem;
    font-weight: 400;
}

.about-card p,
.contact-card p,
.research-card p,
.experience-card p,
.editorial-section p {
    color: var(--text-color);
    line-height: 1.7;
    margin-bottom: 1rem;
}

.about-card a,
.contact-card a {
    color: var(--primary-color);
    text-decoration: none;
}

.about-card a:hover,
.contact-card a:hover {
    text-decoration: underline;
}

.contact-card {
    position: sticky;
    top: 100px;
}

.exp-company {
    color: var(--primary-color);
    font-weight: 600;
}

.exp-date {
    color: var(--text-color);
    font-size: 0.875rem;
    margin-bottom: 1rem;
}

/* Timeline - Dark Modern Style */
.timeline {
    position: relative;
    padding: 3rem 0 3rem 3rem;
    max-width: 1000px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 2px;
    height: 100%;
    background: #3b82f6;
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 2.5rem;
}

.timeline-marker {
    position: absolute;
    left: -5px;
    top: 8px;
    width: 12px;
    height: 12px;
    background: #3b82f6;
    border: 2px solid #1e293b;
    border-radius: 50%;
    z-index: 2;
}

.section-dark .timeline-marker {
    border-color: #1e293b;
}

body.dark-mode .section-dark .timeline-marker {
    border-color: #1f2937;
}

.timeline-date {
    display: inline-block;
    color: #60a5fa;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.75rem;
}

.timeline-content {
    background: transparent;
    padding: 0;
    margin: 0;
    border: none;
}

.timeline-content h3 {
    font-family: var(--font-heading);
    font-size: 1.125rem;
    color: var(--bg-color);
    margin-bottom: 0.5rem;
    font-weight: 400;
    line-height: 1.5;
}

body.dark-mode .section-dark .timeline-content h3 {
    color: var(--text-color);
}

.timeline-content p {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 0.5rem;
    line-height: 1.7;
    font-size: 0.95rem;
}

body.dark-mode .section-dark .timeline-content p {
    color: rgba(229, 231, 235, 0.8);
}

.timeline-content ul {
    margin-left: 1.5rem;
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

body.dark-mode .section-dark .timeline-content ul {
    color: rgba(229, 231, 235, 0.7);
}

.timeline-content ul li {
    margin-bottom: 0.5rem;
}

/* Research Gallery Images */
.research-gallery {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
    justify-content: flex-start;
}

.research-img {
    flex: 0 0 auto;
    max-width: 250px;
    height: 180px;
    object-fit: cover;
    border: 2px solid rgba(96, 165, 250, 0.3);
    background: rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
}

.research-img:hover {
    transform: scale(1.05);
    border-color: rgba(96, 165, 250, 0.6);
    box-shadow: 0 4px 12px rgba(96, 165, 250, 0.3);
}

body.dark-mode .section-dark .research-img {
    border-color: rgba(96, 165, 250, 0.4);
    background: rgba(0, 0, 0, 0.4);
}

body.dark-mode .section-dark .research-img:hover {
    border-color: rgba(96, 165, 250, 0.7);
}

/* Publications */
.publications-filter {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.5rem 1rem;
    background: var(--bg-color);
    border: 1px solid var(--text-color);
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary-color);
    color: var(--bg-color);
    border-color: var(--primary-color);
}

.publication-card {
    background: var(--bg-color);
    padding: 1.5rem;
    border: 1px solid var(--text-color);
    border-left: 3px solid var(--primary-color);
}

.publication-card.hidden {
    display: none;
}

.pub-type {
    display: inline-block;
    color: var(--primary-color);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 0.5rem;
}

.publication-card h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.pub-authors {
    color: var(--text-color);
    font-size: 0.9rem;
    margin-bottom: 0.25rem;
}

.pub-venue {
    color: var(--text-color);
    font-size: 0.875rem;
    font-style: italic;
    margin-bottom: 0.75rem;
}

.pub-links {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.pub-link {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.875rem;
    border-bottom: 1px solid var(--primary-color);
}

.pub-link:hover {
    opacity: 0.7;
}

/* Teaching */
.course-list {
    list-style: none;
}

.course-list li {
    padding-bottom: 1.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--bg-color);
    opacity: 0.9;
}

.course-list li:last-child {
    border-bottom: none;
    padding-bottom: 0;
    margin-bottom: 0;
}

.course-list strong {
    display: block;
    color: var(--bg-color);
    font-size: 1.0625rem;
    margin-bottom: 0.5rem;
}

body.dark-mode .section-dark .course-list strong {
    color: var(--text-color);
}

.course-list p {
    color: var(--bg-color);
    font-size: 0.9375rem;
    opacity: 0.9;
}

body.dark-mode .section-dark .course-list p {
    color: var(--text-color);
}

.mentorship-section {
    background: rgba(255, 255, 255, 0.05);
    padding: 2rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 2rem;
}

body.dark-mode .section-dark .mentorship-section {
    background: rgba(255, 255, 255, 0.03);
    border-color: rgba(255, 255, 255, 0.08);
}

.mentorship-section h3 {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    color: #60a5fa;
    margin-bottom: 1rem;
}

.student-card {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.0625rem;
}

body.dark-mode .section-dark .student-card {
    color: rgba(229, 231, 235, 0.9);
}

.student-card a {
    color: #60a5fa;
    margin-left: 1rem;
    text-decoration: none;
}

.student-card a:hover {
    text-decoration: underline;
}

/* Editorial */
.editorial-section {
    background: var(--bg-color);
    padding: 2rem;
    border: 1px solid var(--text-color);
    margin-top: 2rem;
}

.editorial-section h3 {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    color: var(--text-color);
    margin-bottom: 1rem;
    font-weight: 400;
}

.editorial-section > p {
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-size: 1rem;
}

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

.editorial-list li {
    padding: 0.75rem 1rem;
    background: var(--bg-color);
    border-left: 3px solid var(--primary-color);
    color: var(--text-color);
    font-size: 0.9375rem;
    border: 1px solid var(--text-color);
}

/* Footer */
.footer {
    background: var(--text-color);
    color: var(--bg-color);
    padding: 3rem 2rem 1.5rem;
    text-align: center;
    font-size: 0.875rem;
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    margin-bottom: 2rem;
}

.footer-info {
    margin-bottom: 1.5rem;
}

.footer-info h3 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    color: var(--bg-color);
    margin-bottom: 0.5rem;
    font-weight: 400;
}

.footer-info p {
    color: var(--bg-color);
    margin-bottom: 0.25rem;
    opacity: 0.9;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--bg-color);
    text-decoration: none;
    font-size: 1rem;
    transition: opacity 0.3s ease;
}

.footer-links a:hover {
    opacity: 0.7;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    padding-top: 1.5rem;
    margin-top: 2rem;
}

.footer-bottom p {
    color: var(--bg-color);
    opacity: 0.8;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--primary-color);
    color: var(--bg-color);
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.4);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
}

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 16px rgba(37, 99, 235, 0.5);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

body.dark-mode .back-to-top {
    background: var(--primary-color);
    box-shadow: 0 4px 12px rgba(96, 165, 250, 0.4);
}

body.dark-mode .back-to-top:hover {
    box-shadow: 0 6px 16px rgba(96, 165, 250, 0.5);
}

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

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.6s ease forwards;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    
    .hero-image {
        order: -1;
        display: flex;
        justify-content: center;
    }
    
    .about-grid,
    .teaching-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-card {
        position: relative;
        top: 0;
    }
    
    .timeline {
        padding-left: 2rem;
    }
    
    .timeline::before {
        left: 0;
    }
    
    .timeline-marker {
        left: -5px;
    }
    
    .timeline-item {
        padding-left: 2rem;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 5rem 1.5rem 3rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .section {
        padding: 3rem 1.5rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--bg-color);
        width: 100%;
        padding: 2rem;
        border-right: 1px solid var(--text-color);
        gap: 1.5rem;
        transition: 0.3s;
        align-items: flex-start;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .publications-grid,
    .research-grid,
    .experience-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-links {
        flex-direction: column;
    }
    
    .hero-btn {
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
}