/* ===== CSS Variables ===== */
:root {
    --primary-dark: #0a2540;
    --primary-blue: #1e3a5f;
    --primary-light: #2c5282;
    --accent-amber: #f59e0b;
    --accent-orange: #ea580c;
    --text-dark: #1a202c;
    --text-medium: #4a5568;
    --text-light: #718096;
    --bg-white: #ffffff;
    --bg-light: #f7fafc;
    --bg-lighter: #edf2f7;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Manrope', sans-serif;
    color: var(--text-dark);
    background-color: var(--bg-white);
    line-height: 1.7;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Crimson Pro', serif;
    font-weight: 600;
    line-height: 1.3;
    color: var(--primary-dark);
}

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

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: var(--transition);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo .logo-placeholder {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-text {
    font-family: 'Crimson Pro', serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-dark);
    letter-spacing: -0.5px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2.5rem;
    align-items: center;
}

.nav-link {
    font-weight: 500;
    color: var(--text-dark);
    position: relative;
    padding: 0.5rem 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-amber);
    transition: var(--transition);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--primary-dark);
    transition: var(--transition);
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-blue) 50%, var(--primary-light) 100%);
    overflow: hidden;
    padding-top: 80px;
}

.hero-background {
    position: absolute;
    inset: 0;
    background-image: 
        radial-gradient(circle at 20% 30%, rgba(245, 158, 11, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(234, 88, 12, 0.1) 0%, transparent 50%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0) scale(1); }
    50% { transform: translateY(-20px) scale(1.05); }
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 900px;
    animation: fadeInUp 1s ease-out;
}

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

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4.5rem);
    color: var(--bg-white);
    margin-bottom: 1.5rem;
    font-weight: 700;
    letter-spacing: -1px;
    animation: fadeInUp 1s ease-out 0.2s both;
}

.hero-subtitle {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 2rem;
    font-family: 'Manrope', sans-serif;
    font-weight: 400;
    animation: fadeInUp 1s ease-out 0.4s both;
}

.hero-info {
    margin-bottom: 3rem;
    animation: fadeInUp 1s ease-out 0.6s both;
}

.hero-info p {
    color: rgba(255, 255, 255, 0.8);
    font-size: 1.1rem;
    margin: 0.5rem 0;
}

.cta-button {
    display: inline-block;
    padding: 1rem 2.5rem;
    background: var(--accent-amber);
    color: var(--primary-dark);
    font-weight: 600;
    border-radius: 50px;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(245, 158, 11, 0.3);
    animation: fadeInUp 1s ease-out 0.8s both;
}

.cta-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(245, 158, 11, 0.4);
    background: var(--accent-orange);
}

/* ===== Section Base Styles ===== */
.section {
    padding: 6rem 0;
    position: relative;
}

.section:nth-child(even) {
    background-color: var(--bg-light);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    margin-bottom: 1rem;
    color: var(--primary-dark);
}

.title-underline {
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-amber), var(--accent-orange));
    margin: 0 auto;
    border-radius: 2px;
}

/* ===== About Section ===== */
.about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
    align-items: start;
}

.about-text {
    font-size: 1.1rem;
    line-height: 1.8;
}

.lead-paragraph {
    font-size: 1.3rem;
    color: var(--primary-blue);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.about-text p {
    margin-bottom: 1.5rem;
    color: var(--text-medium);
}

.about-stats {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.stat-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--accent-amber);
    font-family: 'Crimson Pro', serif;
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--text-medium);
    font-weight: 500;
}

/* ===== Research Section ===== */
.research-section {
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-lighter) 100%);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2.5rem;
}

.research-card {
    background: var(--bg-white);
    padding: 2.5rem;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border-top: 4px solid var(--accent-amber);
}

.research-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-top-color: var(--accent-orange);
}

.research-icon {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

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

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

/* ===== Team Section ===== */
.subsection-title {
    font-size: 1.8rem;
    margin: 3rem 0 2rem 0;
    color: var(--primary-dark);
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--border-color);
}

.pi-section {
    margin-bottom: 4rem;
}

.pi-card {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 3rem;
    background: var(--bg-white);
    padding: 3rem;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.member-photo-placeholder {
    width: 200px;
    height: 200px;
    background: linear-gradient(135deg, var(--primary-blue), var(--primary-light));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 3rem;
    font-weight: 700;
    font-family: 'Crimson Pro', serif;
}

.member-info h4 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.member-title {
    font-size: 1.2rem;
    color: var(--accent-amber);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.member-department {
    color: var(--text-medium);
    margin-bottom: 1.5rem;
}

.member-bio {
    color: var(--text-medium);
    line-height: 1.8;
    margin-bottom: 1.5rem;
}

.member-links {
    display: flex;
    gap: 1.5rem;
}

.member-link {
    color: var(--primary-blue);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border: 2px solid var(--primary-blue);
    border-radius: 6px;
    transition: var(--transition);
}

.member-link:hover {
    background: var(--primary-blue);
    color: white;
}

.team-category {
    margin-bottom: 3rem;
}

.team-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 2rem;
}

.member-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    text-align: center;
}

.member-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.member-card .member-photo-placeholder {
    width: 120px;
    height: 120px;
    margin: 0 auto 1.5rem;
    font-size: 1.5rem;
}

.member-card h4 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.member-position {
    color: var(--accent-amber);
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.member-research {
    color: var(--text-medium);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.member-email {
    color: var(--primary-blue);
    font-size: 0.9rem;
    text-decoration: underline;
}

.alumni-list {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.alumni-item {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-medium);
}

.alumni-item:last-child {
    border-bottom: none;
}

/* ===== Publications Section ===== */
.pub-filters {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.75rem 2rem;
    background: var(--bg-white);
    border: 2px solid var(--border-color);
    border-radius: 50px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: 'Manrope', sans-serif;
}

.filter-btn:hover {
    border-color: var(--accent-amber);
    color: var(--accent-amber);
}

.filter-btn.active {
    background: var(--accent-amber);
    border-color: var(--accent-amber);
    color: var(--primary-dark);
}

.publications-list {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    display: grid;
    grid-template-columns: 80px 1fr;
    gap: 2rem;
    padding: 2rem;
    background: var(--bg-white);
    border-radius: 12px;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.publication-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(5px);
}

.pub-year {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-amber);
    font-family: 'Crimson Pro', serif;
}

.pub-title {
    font-size: 1.2rem;
    margin-bottom: 0.75rem;
    color: var(--primary-dark);
}

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

.pub-venue {
    color: var(--text-light);
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

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

.pub-link {
    color: var(--primary-blue);
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0.4rem 1rem;
    border: 1px solid var(--primary-blue);
    border-radius: 6px;
    transition: var(--transition);
}

.pub-link:hover {
    background: var(--primary-blue);
    color: white;
}

/* ===== News Section ===== */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.news-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border-left: 4px solid var(--accent-amber);
}

.news-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.news-date {
    color: var(--accent-orange);
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.news-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-dark);
}

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

/* ===== Contact Section ===== */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.contact-item h4 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-dark);
}

.contact-item p {
    color: var(--text-medium);
    line-height: 1.8;
}

.contact-item a {
    color: var(--primary-blue);
    font-weight: 500;
}

.contact-item a:hover {
    color: var(--accent-amber);
}

.map-placeholder {
    background: var(--bg-lighter);
    border-radius: 12px;
    padding: 4rem 2rem;
    text-align: center;
    color: var(--text-medium);
    border: 2px dashed var(--border-color);
}

/* ===== Footer ===== */
.footer {
    background: var(--primary-dark);
    color: rgba(255, 255, 255, 0.8);
    padding: 4rem 0 2rem 0;
}

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

.footer-section h4 {
    color: white;
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--accent-amber);
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* ===== Responsive Design ===== */
@media (max-width: 968px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--bg-white);
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-menu li {
        padding: 1rem 0;
        width: 100%;
    }

    .hamburger {
        display: flex;
    }

    .about-content {
        grid-template-columns: 1fr;
    }

    .pi-card {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .member-photo-placeholder {
        margin: 0 auto;
    }

    .contact-content {
        grid-template-columns: 1fr;
    }

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

@media (max-width: 640px) {
    .container {
        padding: 0 1.5rem;
    }

    .section {
        padding: 4rem 0;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.1rem;
    }

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

/* ===== Utility Classes ===== */
.hidden {
    display: none !important;
}