:root {
    --bg-color: #0b0a0a;
    --text-primary: #F0F0F0;
    --text-secondary: #8B949E;
    --accent-primary: #ffd500;
    --card-bg: rgba(22, 27, 34, 0.5);
    --border-color: rgba(255, 255, 255, 0.1);
    --font-family: 'Inter', sans-serif;
}

/* --- Global Styles & Reset --- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-family);
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
    user-select: none;
}

/* --- Aurora Background Effect --- */
.aurora-background {
    position: fixed;
    top: 50%;
    left: 50%;
    width: 150vw;
    height: 150vh;
    background: radial-gradient(circle, var(--accent-primary), transparent 40%),
}


/* --- Aurora Background Effect --- */
.aurora-background {
    position: fixed;
    top: 50%;
    left: 50%;
    width: 150vw;
    height: 150vh;
    background: radial-gradient(circle, var(--accent-primary), transparent 40%);
    opacity: 0.1;
    filter: blur(100px);
    transform: translate(-50%, -50%);
    transition: transform 0.5s ease-out;
    will-change: transform;
    z-index: -1;
}

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

.content-section {
    padding: 6rem 0;
    /* This was for the fade-in effect: */
    /* transition: opacity 0.6s ease-out, transform 0.6s ease-out;
    opacity: 0;
    transform: translateY(30px); */
}

.content-section h2 {
    margin-top: 3rem;
}

.content-section.visible {
    opacity: 1;
    transform: translateY(0);
}

h1, h2, h3 {
    color: #FFFFFF;
    font-weight: 700;
}

h1 {
    font-size: 3.5rem;
    line-height: 1.1;
}

h2 {
    font-size: 2.25rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
    text-align: center;
}

h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: #FFFFFF;
}

a.card i {
    position: absolute;
    top: 20px;
    right: 20px;
    color: var(--text-secondary);
    transition: color 0.3s;
}

a.card:hover i {
    color: var(--text-primary);
}

a i {
    font-size: 0.9rem;
}

/* --- Hero Section --- */
.hero-section {
    min-height: 75vh;
    /* width: 100vw; */
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem 0;
}

.hero-content {
    display: flex;
    align-items: center;
    gap: 3rem;
    text-align: center;

}

.hero-text .subtitle {
    font-size: 1.25rem;
    color: var(--accent-primary);
    margin: 1rem 0;
}

.hero-text .research-areas {
    font-size: 1.1rem;
    color: var(--text-primary);
    max-width: 40ch;
}

.research-areas, .contact-links {
    list-style-type: none;
}

.research-areas li, .contact-links li {
    padding: 0.5rem 1rem;
}

.research-areas li i, .contact-links li i {
    margin-right: 0.5rem;
}



.hero-image img {
    width: 330px;
    height: 330px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--accent-primary);
    box-shadow: 0 0 30px var(--bg-color);
}


/* --- Contact Grid Buttons --- */

.contact-section {
    margin: auto;
}

.contact-section h3 {
    margin-top: 2rem;
    color: var(--text-secondary);
    text-align: center;

}

.contact-links a {
    color: var(--text-secondary);
}

    .contact-links a:hover {
    color: var(--accent-primary);
}

.contact-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 2rem;
    justify-content: center;
    align-items: center;
    margin: auto;
}

.contact-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    /* background: #8B949E33; */
    /* border: 2px solid var(--border-color); */
    border-radius: 1rem;
    text-align: center;
    transition: background 0.3s, color 0.3s, border-color 0.3s;
    cursor: pointer;
    /* box-shadow: 0 2px 8px rgba(0,0,0,0.08); */
    width: 75px;
    height: auto;
    aspect-ratio: 1 / 1;
    color: var(--text-secondary);

}

.contact-btn:hover {
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

.contact-btn i {
    color: var(--text-secondary);
    transition: color 0.3s;
    font-size: 1.5rem;
}

.contact-btn:hover i {
    color: var(--accent-primary);
}

.contact-label {
    font-size: .9rem;
    margin-top: 0.25rem;
    font-weight: 500;
    letter-spacing: 0.02em;
}



/* --- Glassmorphism Card --- */
.card {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1rem 2rem 0 2rem;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.card:hover {
    /* removed vertical translate on hover per request; keep a subtle shadow only */
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    border-color: var(--text-secondary);
}



/* --- Highlighted Project Card --- */
.highlighted-project-card {
    border-color: var(--border-color);
    padding: 2.5rem 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.highlighted-title {
    color: var(--accent-primary);
    text-align: center;
    margin-bottom: 0.5rem;
}

.highlighted-description {
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 1rem;
}

.highlighted-image {
    width: 100%;
    border-radius: 1rem;
    box-shadow: 0 4px 16px rgba(0,0,0,0.18);
    object-fit: cover;
    filter: grayscale() brightness(0.7);
    transition: filter 0.3s;
}

.highlighted-project-card:hover .highlighted-image {
    filter: none;
}

/* --- Project selector (small cards) --- */
.project-selector {
    display: flex;
    gap: 1rem;
    margin-top: 1.0rem;
    margin-bottom: 1.5rem;
    justify-content: center;
    align-items: stretch;
}

.small-card {
    flex: 1 1 0;
    min-width: 0;
    max-width: 300px;
    padding: 0.75rem 1rem;
    border-radius: 12px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
    text-align: center;
    text-wrap: balance;
}

.badge {
    background: rgba(0, 163, 255, 0.08);
    color: var(--accent-primary);
    padding: 0.25rem 0.6rem;
    border-radius: 999px;
    font-weight: 700;
    font-size: 0.8rem;
    margin: 0 auto;
}

.selector-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-top: 0.5rem;
    margin-bottom: 0.375rem;
}

.small-card .small-title {
    font-size: 0.95rem;
    color: var(--text-primary);
    font-weight: 600;
}

.small-card:hover {
    transform: translateY(4px);
    box-shadow: 0 8px 18px rgba(0,0,0,0.25);
    filter: brightness(0.9);
}

.small-card:focus {
    transform: translateY(4px);
    outline: none;
    border-color: rgba(255, 213, 0, 0.25);
    box-shadow: 0 0 0 4px rgba(255, 213, 0, 0.08);
}

.small-card.selected {
    transform: translateY(6px);
    border-color: var(--accent-primary);
    box-shadow: 0 8px 24px rgba(37, 28, 0, 0.25);
    filter: brightness(0.75)
}

/* Stack on small screens */
@media (max-width: 600px) {
    .project-selector {
        flex-direction: column;
        gap: 0.75rem;
    }
    .small-card { max-width: none; }
}

/* --- Experience Section (Timeline) --- */
.timeline {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 10px;
    bottom: 10px;
    width: 2px;
    background: linear-gradient(to bottom, transparent, var(--accent-primary), transparent);
}

.timeline-item {
    padding-left: 50px;
    position: relative;
    padding: 2rem;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: 12px;
    top: 12px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background-color: var(--bg-color);
    border: 3px solid var(--accent-primary);
}

.timeline-item .company-date {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.timeline-item ul {
    list-style: none;
    padding-left: 0;
}

.timeline-item li {
    position: relative;
    padding-left: 20px;
    color: var(--text-primary);
}

.timeline-item li::before {
    content: '›';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
    font-weight: bold;
}

/* --- Projects Section --- */
.project-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

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

.project-card h3 b {
    color: var(--accent-primary);
}

.tag {
    background: rgba(0, 163, 255, 0.1);
    color: var(--accent-primary);
    padding: 0.25rem 0.75rem;
    border-radius: 99px;
    font-size: 0.8rem;
    font-weight: 500;
    white-space: nowrap;
}

.project-links {
    margin-top: 1.5rem;
    display: flex;
    gap: 1rem;
}

.btn-primary, .btn-ghost {
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 500;
    display: inline-block;
    border: 1px solid transparent;
}

.btn-primary {
    background-color: var(--accent-primary);
    color: #FFFFFF;
}
.btn-primary:hover {
    background-color: #008ad1;
    color: #FFFFFF;
}

.btn-ghost {
    background-color: transparent;
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}
.btn-ghost:hover {
    background-color: rgba(0, 163, 255, 0.1);
    color: var(--accent-primary);
}

/* --- Publications Section --- */
.project-list {
    list-style: none;
}

.project-list li {
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.project-list li:first-child {
    padding-top: 0;
}

.project-list li:last-child {
    border-bottom: none;
}

.project-title {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-primary);
}

.project-list p {
    margin: 0.25rem 0;
}
.project-grid .authors b {
    color: var(--text-primary);
}

.venue {
    font-style: italic;
    font-size: 0.9rem;
}

.action-links {
    margin-top: 0.5rem;
}
.action-links a {
    margin-right: 1rem;
    font-size: 0.9rem;
}

/* --- About Section --- */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}
.about-column p { color: var(--text-primary); }
.about-column b { color: #FFFFFF; }


/* --- Footer --- */
.footer {
    text-align: center;
    margin-top: 2rem;
    padding: 2rem 2rem 2rem;
    border-top: 1px solid var(--border-color);
}
.footer p { font-size: 1.25rem; color: var(--text-primary); }
.footer .social-links { justify-content: center; }
.footer small { color: var(--text-secondary); margin-top: 2rem; display: block; }
.footer a { color: var(--text-secondary); }
.footer a:hover { color: var(--text-primary); }


/* --- Site Header Navigation --- */
.site-header {
    width: 100vw;
    position: sticky;
    top: 0;
    left: 0;
    z-index: 100;
    background: var(--bg-color);
    opacity: 95%;
    backdrop-filter: blur(12px);
    box-shadow: 0 2px 16px rgba(0,0,0,0.12);
    border-bottom: 1px solid var(--border-color);
}

.nav {
    max-width: 900px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.nav-list li a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 1.05rem;
    letter-spacing: 0.02em;
    padding: 0.5rem 1rem;
}

.nav-list li a:hover,
.nav-list li a:focus {
    color: var(--accent-primary);
}




/* --- Responsive Design --- */
@media (max-width: 850px) {
    h1 { font-size: 2.5rem; }
    h2 { font-size: 1.75rem; }

    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
    }
    .hero-text {
        margin-top: 2rem;
    }
    .social-links {
        justify-content: center;
    }
    
    .project-grid, .about-grid {
        grid-template-columns: 1fr;
    }

    .timeline::before { left: 10px; }
    .timeline-item { padding-left: 35px; }
    .timeline-item::before { left: 2px; }


    .site-header {
        display: none;
    }

    .content-section {
        padding: 2rem 0;
    }


}