/* ============================================
   CSS Variables - Design System
   ============================================ */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-text-primary: #1a1a1a;
    --color-text-secondary: #4a5568;
    --color-text-muted: #718096;
    --color-border: #e2e8f0;
    --color-background: #ffffff;
    --color-background-subtle: #f8fafc;
    --color-background-code: #f8f8f8;
    --color-shadow: rgba(0, 0, 0, 0.1);
    --color-border-code: #eeeeee;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-serif: Georgia, 'Times New Roman', serif;

    /* Spacing */
    --spacing-xs: 8px;
    --spacing-sm: 12px;
    --spacing-md: 20px;
    --spacing-lg: 32px;
    --spacing-xl: 48px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* Dark mode variables */
[data-theme="dark"] {
    --color-text-primary: #f7fafc;
    --color-text-secondary: #e2e8f0;
    --color-text-muted: #a0aec0;
    --color-border: #2d3748;
    --color-background: #1a202c;
    --color-background-subtle: #2d3748;
    --color-background-code: #2d3748;
    --color-shadow: rgba(0, 0, 0, 0.3);
    --color-border-code: #4a5568;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-background);
    font-size: 16px;
    transition: background-color var(--transition-base), color var(--transition-base);
}

.reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.6s ease-out;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

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

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

.container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 28px;
}

/* ============================================
   Top Navigation
   ============================================ */
.top-nav {
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 14px 0;
    box-shadow: var(--shadow-sm);
    backdrop-filter: blur(8px);
    background-color: rgba(255, 255, 255, 0.95);
    transition: all var(--transition-base);
}

[data-theme="dark"] .top-nav {
    background-color: rgba(26, 32, 44, 0.95);
}

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

.nav-brand {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.nav-menu {
    list-style: none;
    display: flex;
    gap: 24px;
    margin: 0;
}

.nav-menu li {
    position: relative;
}

.nav-menu a {
    color: var(--color-text-secondary);
    font-size: 15px;
    text-decoration: none;
    font-weight: 500;
    padding: 6px 0;
    display: block;
    position: relative;
}

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

.nav-menu a:hover {
    color: var(--color-text-primary);
}

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

/* Theme Toggle Button */
.theme-toggle {
    background: none;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
    font-size: 16px;
}

.theme-toggle:hover {
    background-color: var(--color-background-subtle);
    color: var(--color-text-primary);
    border-color: var(--color-primary);
    transform: rotate(15deg);
}

.theme-toggle:active {
    transform: scale(0.95) rotate(15deg);
}

/* ============================================
   Main Container
   ============================================ */
.main-container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 32px 28px 36px;
}

/* ============================================
   About Section
   ============================================ */
.section-about {
    margin-bottom: 36px;
}

.about-grid {
    display: grid;
    grid-template-columns: 224px minmax(0, 1fr);
    gap: 32px;
    margin-bottom: 24px;
    align-items: start;
}

.about-photo {
    width: 224px;
    height: 224px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.about-photo:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.about-photo img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center 15%;
    transition: transform var(--transition-slow);
}

.about-photo:hover img {
    transform: scale(1.05);
}

.info-column {
    display: flex;
    flex-direction: column;
}

.about-info {
    display: grid;
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: 28px;
    align-items: start;
}

.info-column p {
    margin-bottom: 10px;
}

.info-column h1 {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 12px;
    margin-top: 0;
    line-height: 1.15;
    color: var(--color-text-primary);
    letter-spacing: -0.03em;
}

.title {
    font-size: 18px;
    margin-bottom: 8px;
    color: var(--color-text-secondary);
    font-weight: 500;
}

.affiliation {
    font-size: 16px;
    line-height: 1.6;
    margin-bottom: 12px;
    color: var(--color-text-secondary);
}

.email {
    font-size: 14px;
    margin-bottom: 18px;
    color: var(--color-text-muted);
}

.social-icons {
    display: flex;
    gap: 14px;
    font-size: 24px;
}

.social-icons a {
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.social-icons a:hover {
    color: var(--color-primary);
    transform: translateY(-2px);
}

.info-column h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 10px;
    margin-top: 0;
    line-height: 1.2;
}

.interests-list {
    list-style: none;
    padding: 0;
}

.interests-list li {
    margin-bottom: 5px;
    font-size: 16px;
}

.bio {
    line-height: 1.75;
}

.bio p {
    margin-bottom: 20px;
    text-align: justify;
    font-size: 16px;
    color: var(--color-text-secondary);
}

.bio h3 {
    font-size: 19px;
    font-weight: 700;
    margin-top: 28px;
    margin-bottom: 10px;
    color: var(--color-text-primary);
    letter-spacing: -0.01em;
}

/* ============================================
   News Section
   ============================================ */
.section-news {
    margin-bottom: 40px;
}

.section-news h2 {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.news-list {
    list-style: none;
    padding: 0;
}

.news-list li {
    margin-bottom: 14px;
    line-height: 1.65;
    font-size: 16px;
    color: var(--color-text-secondary);
    display: flex;
    align-items: baseline;
    gap: 12px;
}

.news-year {
    font-weight: 600;
    color: var(--color-primary);
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.1) 0%, rgba(37, 99, 235, 0.05) 100%);
    padding: 2px 10px;
    border-radius: 6px;
    font-size: 14px;
    flex-shrink: 0;
    border: 1px solid rgba(37, 99, 235, 0.2);
    letter-spacing: 0.01em;
}

/* ============================================
   Publications Section
   ============================================ */

/* ============================================
   Footer
   ============================================ */
.footer {
    margin-top: 60px;
    padding-top: 30px;
    border-top: 1px solid #e0e0e0;
    text-align: center;
    color: #999;
    font-size: 14px;
}

.section-publications {
    margin-bottom: 40px;
}

.section-publications h2 {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.pub-links-top {
    margin-bottom: 20px;
    font-size: 16px;
}

.pub-links-top a {
    color: var(--color-primary);
    font-weight: 500;
}

.publications-container {
    display: flex;
    flex-direction: column;
}

.publications-loading,
.publications-empty,
.publications-error {
    font-size: 15px;
    color: var(--color-text-muted);
    margin: 16px 0;
}

.publications-error {
    color: #dc2626;
}

.publication {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 24px;
    margin-bottom: 24px;
    padding: 20px;
    border-radius: var(--radius-md);
    align-items: start;
    transition: all var(--transition-base);
    border: 1px solid transparent;
}

.publication:hover {
    background-color: var(--color-background-subtle);
    border-color: var(--color-border);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.publication:last-child {
    margin-bottom: 0;
}

.pub-image {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-md);
}

.pub-image img {
    width: 220px;
    height: 147px;
    display: block;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
    object-fit: cover;
    background: var(--color-background-subtle);
    transition: transform var(--transition-base);
}

.publication:hover .pub-image img {
    transform: scale(1.03);
}

.pub-content {
    min-width: 0;
}

.pub-title {
    font-size: 19px;
    font-weight: 700;
    margin-bottom: 8px;
    line-height: 1.4;
    color: var(--color-text-primary);
    letter-spacing: -0.01em;
}

.pub-authors {
    font-size: 15px;
    margin-bottom: 6px;
    color: var(--color-text-secondary);
    line-height: 1.5;
}

.pub-authors strong {
    font-weight: 700;
    color: var(--color-text-primary);
}

.author-me {
    font-weight: 700;
    color: var(--color-text-primary);
}

.pub-venue {
    font-size: 14px;
    font-style: italic;
    margin-bottom: 8px;
    color: var(--color-text-muted);
}

.pub-links {
    font-size: 14px;
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.pub-links a {
    color: var(--color-primary);
    font-weight: 500;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    background-color: rgba(37, 99, 235, 0.08);
    transition: all var(--transition-fast);
    border: 1px solid rgba(37, 99, 235, 0.15);
}

.pub-links a:hover {
    background-color: rgba(37, 99, 235, 0.15);
    transform: translateY(-1px);
}

.pub-summary {
    font-size: 14px;
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin-top: 10px;
}

.pub-summary-label {
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-right: 6px;
    color: var(--color-primary);
    font-size: 12px;
}

/* ============================================
   Group & Teaching Sections
   ============================================ */
.section-group,
.section-teaching {
    margin-bottom: 36px;
}

.section-group h2,
.section-teaching h2 {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 16px;
    color: #222;
}

.section-group p,
.section-teaching p {
    font-size: 16px;
    color: var(--color-text-secondary);
    font-style: italic;
}

/* ============================================
   Filters
   ============================================ */
.pub-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin-bottom: 24px;
}

.pub-search {
    flex: 1;
    min-width: 200px;
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-background);
    color: var(--color-text-primary);
    font-family: inherit;
    font-size: 15px;
    transition: border-color var(--transition-fast);
}

.pub-search:focus {
    outline: none;
    border-color: var(--color-primary);
}

.pub-year, .pub-type {
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-background);
    color: var(--color-text-primary);
    font-family: inherit;
    font-size: 15px;
    cursor: pointer;
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
    .container {
        padding: 0 20px;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .about-photo {
        width: 180px;
        height: 180px;
        margin: 0 auto;
    }

    .about-info {
        grid-template-columns: 1fr;
        gap: 20px;
        text-align: center;
    }
    
    .info-column {
        align-items: center;
    }
    
    .social-icons {
        justify-content: center;
        flex-wrap: wrap;
    }

    .interests-list {
        display: inline-block;
        text-align: left;
    }

    .bio p {
        text-align: left;
    }

    .publication {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .pub-image {
        display: flex;
        justify-content: center;
    }

    .pub-image img {
        width: 100%;
        max-width: 280px;
        height: auto;
    }

    .nav-menu {
        gap: 16px;
        font-size: 14px;
    }

    .info-column h1 {
        font-size: 32px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .main-container {
        padding: 24px 16px;
    }

    .nav-brand {
        font-size: 16px;
    }

    .nav-menu {
        display: flex; /* Prevent hiding on mobile */
        gap: 12px;
        font-size: 14px;
    }

    .theme-toggle {
        width: 32px;
        height: 32px;
        font-size: 14px;
    }

    .info-column h1 {
        font-size: 26px;
    }

    .section-publications h2,
    .section-news h2 {
        font-size: 24px;
    }

    .publication {
        padding: 14px;
        margin-bottom: 18px;
    }

    .pub-title {
        font-size: 17px;
    }
    
    .about-photo {
        width: 150px;
        height: 150px;
    }
}