/* =========================================
   Global Variables & Theming
   ========================================= */
:root {
    --color-primary: #1a202c; /* Deep slate */
    --color-secondary: #4a5568; /* Lighter slate */
    --color-accent: #3182ce; /* Academic blue */
    --color-background: #f7fafc; /* Very light gray */
    --color-surface: #ffffff; /* White cards */
    --font-heading: 'Inter', sans-serif;
    --font-body: 'Merriweather', serif;
}

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

body {
    font-family: var(--font-body);
    background-color: var(--color-background);
    color: var(--color-primary);
    line-height: 1.6;
}

h1, h2, h3, h4, h5, h6, .logo, .nav-links a, .btn, .pub-link {
    font-family: var(--font-heading);
}

/* =========================================
   Global Navigation
   ========================================= */
.site-nav {
    background-color: var(--color-surface);
    border-bottom: 1px solid #e2e8f0;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.logo {
    font-weight: 700;
    font-size: 1.5rem;
    text-decoration: none;
    color: var(--color-primary);
    letter-spacing: -0.5px;
}

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

.nav-links a {
    text-decoration: none;
    color: var(--color-secondary);
    font-weight: 600;
    font-size: 0.9rem;
    transition: color 0.3s ease, border-bottom 0.3s ease;
}

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

/* Active Nav State */
.nav-links a.active {
    color: var(--color-accent);
    border-bottom: 2px solid var(--color-accent);
    padding-bottom: 0.3rem; 
}

/* =========================================
   Buttons
   ========================================= */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background-color: var(--color-accent);
    color: var(--color-surface);
    text-decoration: none;
    border-radius: 4px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: background-color 0.3s ease;
    align-self: flex-start;
}

.btn:hover {
    background-color: #2b6cb0; /* Darker blue */
}

/* =========================================
   Home Page Specific Styles
   ========================================= */
/* Hero Section */
.hero {
    background-color: var(--color-primary);
    color: var(--color-surface);
    padding: 6rem 2rem;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    line-height: 1.2;
    letter-spacing: -1px;
}

.hero .subtitle {
    font-size: 1.2rem;
    color: #cbd5e0;
    font-weight: 300;
}

/* Main Layout & Cards */
.content-wrapper {
    max-width: 1200px;
    margin: 4rem auto;
    padding: 0 2rem;
}

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

.hub-card {
    background: var(--color-surface);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    display: flex;
    flex-direction: column;
}

.hub-card h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--color-primary);
}

.hub-card p {
    margin-bottom: 2rem;
    color: var(--color-secondary);
    flex-grow: 1; /* Pushes the button to the bottom */
}

/* =========================================
   Internal Pages / Research Styles
   ========================================= */
/* Internal Page Headers */
.page-header {
    background-color: var(--color-primary);
    color: var(--color-surface);
    padding: 5rem 2rem 4rem; 
    margin-bottom: 3rem;
    border-bottom: 2px solid #e2e8f0; 
}

.page-header .header-content {
    max-width: 1200px;
    margin: 0 auto;
}

.page-header h1 {
    font-size: 2.8rem; 
    margin-bottom: 0.5rem;
    letter-spacing: -0.5px;
}

.page-header .subtitle {
    color: #cbd5e0;
    font-size: 1.15rem;
    font-weight: 300;
}

.research-page-header {
    border-bottom: none; 
}

/* Research Content Layout */
.research-wrapper {
    max-width: 1000px; 
}

.research-intro {
    max-width: 800px;
    margin-bottom: 3.5rem;
    font-size: 1.1rem;
    line-height: 1.7; 
}

.research-intro h2 {
    margin-bottom: 1.25rem;
    color: var(--color-primary);
    font-size: 1.6rem;
    font-weight: 700;
}

.section-divider {
    border: 0;
    height: 1px;
    background: #cbd5e0; 
    margin: 3.5rem 0;
}

/* Publication Lists */
.publications-section {
    margin-bottom: 4.5rem;
}

.publications-section h3 {
    margin-bottom: 2.5rem;
    font-size: 1.7rem;
    color: var(--color-primary); 
    border-bottom: 3px solid var(--color-accent);
    display: inline-block;
    padding-bottom: 0.75rem;
    font-weight: 700;
}

.pub-list {
    list-style: none;
    max-width: 900px;
}

.pub-item {
    margin-bottom: 3rem; 
    padding: 1.5rem;
    background-color: var(--color-surface);
    border-radius: 8px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05); 
    border-left: 4px solid #e2e8f0; 
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-left-color 0.3s ease;
}

.pub-item:hover {
    transform: translateY(-2px); 
    box-shadow: 0 4px 8px rgba(0,0,0,0.1); 
    border-left-color: var(--color-accent); 
}

.pub-item h4 {
    font-size: 1.35rem; 
    color: var(--color-primary);
    margin-bottom: 0.4rem;
    line-height: 1.4;
    font-weight: 600;
}

.pub-meta {
    font-size: 0.95rem;
    color: var(--color-secondary);
    margin-bottom: 0.75rem;
}

.pub-desc {
    font-size: 1rem;
    color: #4a5568;
    margin-bottom: 1.25rem;
    line-height: 1.6;
}

.pub-link {
    font-size: 0.9rem; 
    font-weight: 600;
    color: var(--color-accent);
    text-decoration: none;
    text-transform: uppercase;
    letter-spacing: 0.7px;
    padding: 0.3rem 0; 
    display: inline-block;
    border-bottom: 2px solid transparent; 
    transition: color 0.3s ease, border-bottom-color 0.3s ease;
}

.pub-link:hover {
    color: #2b6cb0;
    border-bottom-color: #2b6cb0; 
}

/* =========================================
   Footer
   ========================================= */
.site-footer {
    text-align: center;
    padding: 2rem;
    background-color: var(--color-surface);
    border-top: 1px solid #e2e8f0;
    color: var(--color-secondary);
    font-size: 0.9rem;
    font-family: var(--font-heading);
    margin-top: 4rem; 
}

/* =========================================
   Responsive Adjustments
   ========================================= */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem;
    }
    
    .hero h1, .page-header h1 {
        font-size: 2.2rem;
    }
    
    .pub-item {
        padding: 1rem;
    }
}