/* Global Variables */
:root {
    --primary-color: #333;
    --secondary-color: #666;
    --accent-color: #0066cc;
    --background-color: #fff;
    --light-gray: #f5f5f5;
    --dark-gray: #222;
    --border-color: #ddd;
    --font-main: 'Arial', sans-serif;
    --font-heading: 'Helvetica', sans-serif;
    --transition: all 0.3s ease;
    --spacing-unit: 1rem;
}

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

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

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    margin-bottom: 1rem;
    line-height: 1.2;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
    margin-top: 2rem;
}

h3 {
    font-size: 1.5rem;
    margin-top: 1.5rem;
}

p {
    margin-bottom: 1rem;
}

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

a:hover {
    text-decoration: underline;
}

ul, ol {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

/* Header Styles */
.site-header {
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--background-color);
}

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

.logo a {
    display: flex;
    align-items: center;
    text-decoration: none;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-left: 0.5rem;
}

.main-nav ul {
    display: flex;
    list-style: none;
    margin: 0;
}

.main-nav li {
    margin-left: 2rem;
}

.main-nav a {
    color: var(--primary-color);
    font-weight: bold;
}

.main-nav a.active,
.main-nav a:hover {
    color: var(--accent-color);
    text-decoration: none;
}

/* Hero Section */
.hero {
    background-color: var(--light-gray);
    padding: 4rem 0;
    margin-bottom: 2rem;
}

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

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.lead {
    font-size: 1.25rem;
    color: var(--secondary-color);
    margin-bottom: 2rem;
}

/* Content Sections */
.content-section {
    padding: 2rem 0;
}

.page-header {
    background-color: var(--light-gray);
    padding: 3rem 0;
    margin-bottom: 2rem;
}

/* Research Cards */
.research-card {
    display: flex;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    overflow: hidden;
    margin-bottom: 2rem;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.research-image {
    flex: 0 0 300px;
}

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

.research-content {
    flex: 1;
    padding: 1.5rem;
}

.research-year {
    color: var(--secondary-color);
    font-style: italic;
    margin-bottom: 1rem;
}

.btn-download {
    display: inline-block;
    background-color: var(--accent-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 0.25rem;
    margin-top: 1rem;
    transition: var(--transition);
}

.btn-download:hover {
    background-color: #0055aa;
    text-decoration: none;
}

/* Footer */
.site-footer {
    background-color: var(--dark-gray);
    color: white;
    padding: 3rem 0 1.5rem;
    margin-top: 3rem;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin-bottom: 2rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
}

.footer-logo span {
    margin-left: 0.5rem;
    font-size: 1.25rem;
    font-weight: bold;
}

.footer-contact, 
.footer-links {
    margin-bottom: 1.5rem;
}

.footer-contact h3,
.footer-links h3 {
    margin-bottom: 1rem;
    color: white;
}

.footer-links ul {
    list-style: none;
    margin: 0;
}

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Responsive Styles */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
    }
    
    .main-nav {
        margin-top: 1rem;
    }
    
    .main-nav ul {
        flex-direction: column;
        text-align: center;
    }
    
    .main-nav li {
        margin: 0.5rem 0;
    }
    
    .research-card {
        flex-direction: column;
    }
    
    .research-image {
        flex: 0 0 200px;
    }
    
    .footer-content {
        flex-direction: column;
    }
}