/* ============================================
   CSS VARIABLES & THEME
   ============================================ */
:root {
    --bg-primary: #fefdfb;
    --bg-secondary: #f8f7f4;
    --bg-accent: #f0eeea;
    --text-primary: #1a1a1a;
    --text-secondary: #4a4a4a;
    --text-muted: #717171;
    --accent-primary: #2563eb;
    --accent-hover: #1d4ed8;
    --border-color: #e5e4e1;
    --border-dark: #d1d0cd;
    
    /* Tag colors */
    --tag-few-shot: #8b5cf6;
    --tag-mech-interp: #06b6d4;
    --tag-compositionality: #f59e0b;
    --tag-pragmatics: #ec4899;
    --tag-vision-language: #10b981;
    --tag-robotics: #ef4444;
    --tag-edai: #6366f1;
    
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.12);

    --nav-bg: rgba(254, 253, 251, 0.95);
}

/* Dark Mode */
[data-theme="dark"] {
    --bg-primary: #121212;
    --bg-secondary: #1a1a1a;
    --bg-accent: #242424;
    --text-primary: #f0f0f0;
    --text-secondary: #b0b0b0;
    --text-muted: #808080;
    --accent-primary: #60a5fa;
    --accent-hover: #93c5fd;
    --border-color: #2a2a2a;
    --border-dark: #3a3a3a;
    
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.4);

    --nav-bg: rgba(18, 18, 18, 0.95);
}

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

html {
    scroll-behavior: smooth;
}

/* Smooth theme transitions */
body, nav, .publication, .tag-filter, .research-figure-container, 
.bibtex-modal, .bibtex-content, .figure-overlay, .news-item {
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

body {
    font-family: 'Newsreader', Georgia, serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    font-size: 17px;
}

/* ============================================
   LAYOUT
   ============================================ */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ============================================
   NAVIGATION
   ============================================ */
nav {
    position: sticky;
    top: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    z-index: 100;
    padding: 1rem 0;
}

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

.nav-name {
    font-family: 'Inter', sans-serif;
    font-weight: 600;
    font-size: 1rem;
    color: var(--text-primary);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    color: var(--text-muted);
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text-primary);
}

/* ============================================
   THEME TOGGLE SLIDER
   ============================================ */
.theme-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-left: 1rem;
}

.theme-slider {
    position: relative;
    width: 52px;
    height: 28px;
}

.theme-slider input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-accent);
    border: 1px solid var(--border-dark);
    border-radius: 28px;
    transition: all 0.3s ease;
}

.slider::before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 3px;
    bottom: 3px;
    background: var(--bg-primary);
    border-radius: 50%;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

/* Sun icon (shown in dark mode) */
.slider::after {
    content: "☀️";
    position: absolute;
    right: 6px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 12px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

/* When checked (light mode) */
.theme-slider input:checked + .slider {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
}

.theme-slider input:checked + .slider::before {
    transform: translateX(24px);
    background: white;
}

/* Moon icon positioning */
.slider-icons {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 6px;
    pointer-events: none;
    font-size: 12px;
}

.slider-icons .sun {
    opacity: 0;
    transition: opacity 0.3s ease;
}

.slider-icons .moon {
    opacity: 1;
    transition: opacity 0.3s ease;
}

[data-theme="dark"] .slider-icons .sun {
    opacity: 1;
}

[data-theme="dark"] .slider-icons .moon {
    opacity: 0;
}

/* ============================================
   HEADER / HERO
   ============================================ */
.header {
    padding: 4rem 0 3rem;
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    display: grid;
    grid-template-columns: 160px 1fr;
    gap: 2.5rem;
    align-items: start;
}

.profile-image {
    width: 160px;
    height: 160px;
    border-radius: 12px;
    object-fit: cover;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.profile-placeholder {
    width: 160px;
    height: 160px;
    border-radius: 12px;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-accent) 100%);
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-family: 'Inter', sans-serif;
    font-size: 0.8rem;
}

.header-info h1 {
    font-size: 2.25rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.header-info .tagline {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-style: italic;
}

.header-links {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.header-links a {
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    color: var(--accent-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.35rem;
    transition: color 0.2s ease;
}

.header-links a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.header-links svg {
    width: 16px;
    height: 16px;
}

.bio {
    color: var(--text-secondary);
    font-size: 1.05rem;
    line-height: 1.8;
}

.bio strong {
    color: var(--text-primary);
    font-weight: 500;
}

.advisor-link {
    color: var(--accent-primary);
    text-decoration: none;
}

.advisor-link:hover {
    text-decoration: underline;
}

/* ============================================
   NEWS SECTION
   ============================================ */
.news-section {
    padding: 2.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.news-section .section-title {
    margin-bottom: 1.5rem;
}

.news-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.news-item {
    display: grid;
    grid-template-columns: 100px 1fr;
    gap: 1rem;
    padding: 1rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    align-items: start;
}

.news-date {
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-muted);
    white-space: nowrap;
}

.news-content {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.news-content strong {
    color: var(--text-primary);
    font-weight: 500;
}

.news-content em {
    color: var(--text-primary);
}

.news-links {
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
}

.news-link {
    color: var(--accent-primary);
    text-decoration: none;
}

.news-link:hover {
    text-decoration: underline;
}

/* ============================================
   RESEARCH FIGURE SECTION
   ============================================ */
.research-figure-section {
    padding: 3rem 0;
    border-bottom: 1px solid var(--border-color);
}

.research-figure-container {
    border: 2px solid var(--border-dark);
    border-radius: 12px;
    overflow: hidden;
    background: var(--bg-secondary);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}

.research-figure-container:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.figure-expand-hint {
    position: absolute;
    top: 1rem;
    right: 1rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-family: 'Inter', sans-serif;
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--bg-primary);
    padding: 0.4rem 0.75rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    opacity: 0.9;
    transition: all 0.2s ease;
    pointer-events: none;
}

.figure-expand-hint svg {
    width: 14px;
    height: 14px;
}

.research-figure-container:hover .figure-expand-hint {
    opacity: 1;
    background: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
}

.research-figure {
    width: 100%;
    height: auto;
    display: block;
}

.research-figure-placeholder {
    width: 100%;
    aspect-ratio: 16/9;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-family: 'Inter', sans-serif;
    flex-direction: column;
    gap: 0.5rem;
}

.research-figure-placeholder svg {
    width: 48px;
    height: 48px;
    opacity: 0.5;
}

.figure-caption {
    padding: 1rem 1.25rem;
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.figure-link {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-family: 'Inter', sans-serif;
    font-size: 0.8rem;
    color: var(--accent-primary);
    text-decoration: none;
    margin-top: 0.5rem;
}

.figure-link:hover {
    text-decoration: underline;
}

/* Fullscreen overlay */
.figure-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.9);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    cursor: zoom-out;
}

.figure-overlay.active {
    display: flex;
}

.figure-overlay img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

.figure-overlay-close {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    border: none;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s ease;
}

.figure-overlay-close:hover {
    background: rgba(255, 255, 255, 0.2);
}

/* ============================================
   SECTION STYLING
   ============================================ */
section {
    padding: 3rem 0;
    border-bottom: 1px solid var(--border-color);
}

section:last-of-type {
    border-bottom: none;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 500;
    letter-spacing: -0.01em;
}

/* ============================================
   TAG FILTERS
   ============================================ */
.tag-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 2rem;
}

.tag-filter {
    font-family: 'Inter', sans-serif;
    font-size: 0.75rem;
    font-weight: 500;
    padding: 0.4rem 0.75rem;
    border-radius: 100px;
    border: 1.5px solid var(--border-color);
    background: var(--bg-primary);
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-secondary);
}

.tag-filter:hover {
    border-color: var(--border-dark);
}

.tag-filter.active {
    color: white;
    border-color: transparent;
}

/* Colored borders for inactive state */
.tag-filter[data-tag="few-shot"] { border-color: var(--tag-few-shot); color: var(--tag-few-shot); }
.tag-filter[data-tag="mech-interp"] { border-color: var(--tag-mech-interp); color: var(--tag-mech-interp); }
.tag-filter[data-tag="compositionality"] { border-color: var(--tag-compositionality); color: var(--tag-compositionality); }
.tag-filter[data-tag="pragmatics"] { border-color: var(--tag-pragmatics); color: var(--tag-pragmatics); }
.tag-filter[data-tag="vision-language"] { border-color: var(--tag-vision-language); color: var(--tag-vision-language); }
.tag-filter[data-tag="robotics"] { border-color: var(--tag-robotics); color: var(--tag-robotics); }
.tag-filter[data-tag="edai"] { border-color: var(--tag-edai); color: var(--tag-edai); }

/* Filled background for active state */
.tag-filter[data-tag="few-shot"].active { background: var(--tag-few-shot); color: white; }
.tag-filter[data-tag="mech-interp"].active { background: var(--tag-mech-interp); color: white; }
.tag-filter[data-tag="compositionality"].active { background: var(--tag-compositionality); color: white; }
.tag-filter[data-tag="pragmatics"].active { background: var(--tag-pragmatics); color: white; }
.tag-filter[data-tag="vision-language"].active { background: var(--tag-vision-language); color: white; }
.tag-filter[data-tag="robotics"].active { background: var(--tag-robotics); color: white; }
.tag-filter[data-tag="edai"].active { background: var(--tag-edai); color: white; }

.clear-filters {
    font-family: 'Inter', sans-serif;
    font-size: 0.75rem;
    color: var(--text-muted);
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.4rem 0.5rem;
    text-decoration: underline;
}

.clear-filters:hover {
    color: var(--text-primary);
}

/* ============================================
   PUBLICATIONS
   ============================================ */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.publication {
    display: flex;
    gap: 1.25rem;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    transition: all 0.2s ease;
}

.publication:hover {
    border-color: var(--border-dark);
    box-shadow: var(--shadow-sm);
}

.publication.hidden {
    display: none;
}

.pub-image {
    flex-shrink: 0;
    width: 140px;
    height: 90px;
    border-radius: 6px;
    overflow: hidden;
    background: var(--bg-accent);
    border: 1px solid var(--border-color);
}

.pub-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.pub-content {
    flex: 1;
    min-width: 0;
}

.pub-title {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.pub-title a {
    color: var(--text-primary);
    text-decoration: none;
}

.pub-title a:hover {
    color: var(--accent-primary);
}

.pub-authors {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.pub-authors .me {
    font-weight: 500;
    color: var(--text-primary);
}

.pub-authors .author-link {
    color: var(--accent-primary);
    text-decoration: none;
}

.pub-authors .author-link:hover {
    text-decoration: underline;
}

.pub-venue {
    font-size: 0.9rem;
    color: var(--text-muted);
    font-style: italic;
    margin-bottom: 0.75rem;
}

.pub-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-bottom: 0.75rem;
}

.pub-tag {
    font-family: 'Inter', sans-serif;
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    color: white;
}

.pub-tag.few-shot { background: var(--tag-few-shot); }
.pub-tag.mech-interp { background: var(--tag-mech-interp); }
.pub-tag.compositionality { background: var(--tag-compositionality); }
.pub-tag.pragmatics { background: var(--tag-pragmatics); }
.pub-tag.vision-language { background: var(--tag-vision-language); }
.pub-tag.robotics { background: var(--tag-robotics); }
.pub-tag.edai { background: var(--tag-edai); }

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

.pub-link {
    font-family: 'Inter', sans-serif;
    font-size: 0.8rem;
    color: var(--accent-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.3rem;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
}

.pub-link:hover {
    text-decoration: underline;
}

.pub-link svg {
    width: 14px;
    height: 14px;
}

/* ============================================
   BIBTEX MODAL
   ============================================ */
.bibtex-modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

.bibtex-modal.active {
    display: flex;
}

.bibtex-content {
    background: var(--bg-primary);
    border-radius: 12px;
    max-width: 700px;
    width: 100%;
    max-height: 80vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.bibtex-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.bibtex-header h3 {
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    font-weight: 600;
}

.bibtex-close {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-muted);
    padding: 0.5rem;
}

.bibtex-close:hover {
    color: var(--text-primary);
}

.bibtex-body {
    padding: 1.5rem;
    overflow-y: auto;
}

.bibtex-code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    background: var(--bg-secondary);
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
    white-space: pre-wrap;
    word-break: break-all;
}

.bibtex-copy {
    margin-top: 1rem;
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    padding: 0.6rem 1.2rem;
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: background 0.2s ease;
}

.bibtex-copy:hover {
    background: var(--accent-hover);
}

/* ============================================
   FOOTER
   ============================================ */
footer {
    padding: 3rem 0;
    text-align: center;
    color: var(--text-muted);
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 768px) {
    .header-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .profile-image,
    .profile-placeholder {
        margin: 0 auto;
    }

    .header-links {
        justify-content: center;
    }

    .nav-links {
        gap: 1rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .news-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }

    .publication {
        flex-direction: column;
    }

    .pub-image {
        width: 100%;
        height: 160px;
    }
}

/* ============================================
   LINK COLORS - Prevent purple visited state
   ============================================ */

/* Keep all links their original color even after visiting */
a:visited {
    color: inherit;
}

.header-links a:visited,
.advisor-link:visited,
.figure-link:visited {
    color: var(--accent-primary);
}

.pub-link:visited,
.news-link:visited {
    color: var(--accent-primary);
}

/* ============================================
   PAPER LINKS - Color-coded by research area
   ============================================ */

.paper-link {
    text-decoration: none;
    font-weight: 500;
}

.paper-link:hover {
    text-decoration: underline;
}

/* Few-shot / Mech-interp links (purple-cyan) */
.paper-link.fewshot,
.paper-link.fewshot:visited {
    color: var(--tag-few-shot);
}

/* Compositionality links (orange) */
.paper-link.compositionality,
.paper-link.compositionality:visited {
    color: var(--tag-compositionality);
}

/* Pragmatics links (pink) */
.paper-link.pragmatics,
.paper-link.pragmatics:visited {
    color: var(--tag-pragmatics);
}

/* Caption section headings */
.caption-heading.fewshot {
    color: var(--tag-few-shot);
}

.caption-heading.compositionality {
    color: var(--tag-compositionality);
}

.caption-heading.pragmatics {
    color: var(--tag-pragmatics);
}

.paper-link {
    text-decoration: underline;
    text-underline-offset: 2px;
    font-weight: 500;
}

.paper-link:hover {
    text-decoration-thickness: 2px;
}

/* ============================================
   FIX NAVIGATION SCROLL OFFSET
   ============================================ */

section, header {
    scroll-margin-top: 80px;
}

/* ============================================
   FIGURE IMAGE WRAPPER
   ============================================ */

.figure-image-wrapper {
    position: relative;
    cursor: pointer;
}

.figure-image-wrapper:hover .figure-expand-hint {
    opacity: 1;
    background: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
}

/* ============================================
   UTILITY
   ============================================ */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}