:root {
    --bg-primary: #1a1d2e;
    --bg-secondary: #252836;
    --bg-tertiary: #2d3142;
    --text-primary: #ffffff;
    --text-secondary: #b8c1ec;
    --accent: #a855f7;
    --accent-glow: rgba(168, 85, 247, 0.3);
    --border: rgba(255, 255, 255, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header & Navigation */
header {
    background: linear-gradient(to bottom, #000000 0%, #1a1d2e 100%);
    border-bottom: 1px solid var(--border);
    padding: 1.5rem 2rem;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 2rem;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.site-name {
    font-family: 'Courier New', monospace;
    font-size: 1.8rem;
    font-weight: 500;
    color: var(--text-primary);
    letter-spacing: 1px;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 0.5rem;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.75rem 1.5rem;
    transition: color 0.3s ease, text-shadow 0.3s ease;
    font-weight: 500;
}

nav a:hover {
    color: var(--accent);
    text-shadow: 0 0 8px var(--accent-glow);
}

nav a.active {
    color: var(--accent);
}

/* Main Content */
main {
    flex: 1;
    max-width: 1400px;
    margin: 0 auto;
    padding: 4rem 2rem;
    width: 100%;
    position: relative;
}

.home-page main::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 150%;
    background-image: url('collAIder.png');
    background-size: 1000px;
    background-position: center 0rem;
    background-repeat: no-repeat;
    opacity: 0.70;
    mix-blend-mode: screen;
    pointer-events: none;
    z-index: 0;
}


main::after {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
    pointer-events: none;
    animation: pulse 4s ease-in-out infinite;
    z-index: 0;
}

main > * {
    position: relative;
    z-index: 1;
}

.hero {
    text-align: center;
    padding: 4rem 0 6rem;
    position: relative;
}

@keyframes pulse {
    0%, 100% { opacity: 0.45; transform: translateX(-50%) scale(1); }
    50% { opacity: 0.8; transform: translateX(-50%) scale(1.1); }
}

.hero h1 {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    letter-spacing: -1px;
}

.hero .tagline {
    font-size: 1.4rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 2rem;
}

/* Content Sections */
.section {
    margin-bottom: 5rem;
}

.section-header {
    margin-bottom: 3rem;
    border-left: 4px solid var(--accent);
    padding-left: 2rem;
    background: transparent;
}

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Cards */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.card {
    background: rgba(37, 40, 54, 0.7);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), transparent);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.card:hover::before {
    transform: scaleX(1);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 40px rgba(168, 85, 247, 0.2);
    border-color: var(--accent);
}

.card h3 {
    color: var(--accent);
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Team Cards */
.team-member {
    text-align: center;
}

.team-photo {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    border: 3px solid var(--accent);
    margin: 0 auto 1.5rem;
    overflow: hidden;
    background: var(--bg-tertiary);
}

/* Publications List */
.publication-item {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    margin-bottom: 1.5rem;
    transition: all 0.3s ease;
}

.publication-item:hover {
    transform: translateX(10px);
    border-color: var(--accent);
    box-shadow: -5px 0 20px rgba(168, 85, 247, 0.2);
}

.publication-item h3 {
    color: var(--text-primary);
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.publication-meta {
    color: var(--accent);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.publication-item p {
    color: var(--text-secondary);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, var(--accent) 0%, #7c3aed 100%);
    color: var(--bg-primary);
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    box-shadow: 0 5px 20px var(--accent-glow);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px var(--accent-glow);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--accent);
    border: 2px solid var(--accent);
}

/* Footer */
footer {
    background: linear-gradient(to bottom, #1a1d2e 0%, #000000 100%);
    border-top: 1px solid var(--border);
    padding: 3rem 2rem;
    margin-top: auto;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
}

.footer-section h3 {
    color: var(--accent);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.footer-section p,
.footer-section a {
    color: var(--text-secondary);
    text-decoration: none;
    display: block;
    margin-bottom: 0.5rem;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: var(--accent);
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        text-align: center;
    }
    
    nav ul {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero .tagline {
        font-size: 1.1rem;
    }
    
    .section-header h2 {
        font-size: 2rem;
    }
    
    main {
        padding: 2rem 1rem;
    }
}

.team-photo img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 50%;
}

.institution {
    color: var(--accent);
    margin-bottom: 1rem;
}

.read-more-btn {
    background: none;
    border: none;
    color: white;
    font-size: 1.1rem;
    font-weight: 400;
    cursor: pointer;
    margin: 1rem auto 0 auto;   /* centers horizontally */
    
    display: flex;
    flex-direction: column;
    align-items: center;        /* centers arrow + text */
    
    text-align: center;         /* centers text */
}

/* The small upside-down arrow */
.read-more-btn::after {
    content: "⌄";
    font-size: 0.9rem;
    transition: transform 0.3s ease;
}

/* Rotate arrow when open */
.bio.open + .read-more-btn::after {
    transform: rotate(180deg);
}

.read-more-btn:hover {
    opacity: 0.8;
    color: var(--accent);      /* optional: turns purple on hover */
}


.bio {
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.4s ease, opacity 0.3s ease;
}

.bio.open {
    max-height: 500px;
    opacity: 1;
}