:root {
    /* Colors */
    --bg-color: #ffffff;
    --bg-light: #f9f9f9;
    --text-primary: #222222;
    --text-secondary: #555555;
    --text-tertiary: #888888;
    --accent-color: #0056b3;
    /* Academic Blue */
    --accent-hover: #003d82;
    --border-color: #eaeaea;

    /* Typography */
    --font-heading: 'Merriweather', serif;
    --font-body: 'Inter', sans-serif;

    /* Spacing */
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    --container-width: 800px;
    /* Narrower for better reading experience */
}

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

body {
    font-family: --font-body, sans-serif;
    /* Fallback */
    font-family: var(--font-body);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s ease;
}

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

ul {
    list-style: none;
}

/* Layout Utilities */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-xl) 0;
}

.bg-light {
    background-color: var(--bg-light);
}

/* Header */
.site-header {
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid transparent;
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(5px);
    z-index: 100;
    transition: border-color 0.3s ease;
}

.site-header:hover {
    border-bottom-color: var(--border-color);
}

.site-header.scrolled {
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    border-bottom-color: var(--border-color);
}

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

.logo {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1.25rem;
    letter-spacing: -0.02em;
}

.main-nav ul {
    display: flex;
    gap: var(--spacing-lg);
}

.main-nav a {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.main-nav a:hover {
    color: var(--text-primary);
}

/* Hero Section */
.hero-section {
    padding: 6rem 0 4rem;
}

.hero-content h1 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    line-height: 1.3;
    margin-bottom: var(--spacing-lg);
    font-weight: 300;
}

.hero-content .highlight {
    font-weight: 700;
    color: var(--text-primary);
    position: relative;
    display: inline-block;
}

.hero-content .highlight::after {
    content: '';
    position: absolute;
    bottom: 2px;
    left: 0;
    width: 100%;
    height: 8px;
    background-color: rgba(0, 86, 179, 0.1);
    z-index: -1;
}

.lead {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    max-width: 600px;
}

.hero-links {
    display: flex;
    gap: var(--spacing-md);
}

.btn {
    display: inline-block;
    padding: 0.6rem 1.2rem;
    border-radius: 4px;
    font-weight: 500;
    font-size: 0.95rem;
    transition: all 0.2s ease;
}

.btn-primary {
    background-color: var(--text-primary);
    color: #fff;
}

.btn-primary:hover {
    background-color: #000;
    transform: translateY(-1px);
}

.btn-secondary {
    background-color: var(--bg-light);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: #eaeaea;
}

/* Section Titles */
.section-title {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--bg-light);
    display: inline-block;
}

/* Publications / Paper Cards */
.paper-card {
    display: grid;
    grid-template-columns: 60px 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    align-items: baseline;
}

.paper-year {
    font-family: var(--font-body);
    font-weight: 600;
    color: var(--text-tertiary);
    font-size: 0.9rem;
    text-align: right;
}

.paper-title {
    font-family: var(--font-heading);
    font-size: 1.2rem;
    margin-bottom: var(--spacing-sm);
    font-weight: 700;
}

.paper-authors {
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.paper-venue {
    font-style: italic;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: 0.95rem;
}

.tag {
    display: inline-block;
    background-color: #fff0f0;
    color: #d32f2f;
    font-size: 0.75rem;
    padding: 2px 6px;
    border-radius: 4px;
    margin-left: 8px;
    font-style: normal;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.paper-abstract {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: 0.95rem;
    line-height: 1.7;
}

.paper-links {
    display: flex;
    gap: var(--spacing-md);
}

.link-item {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent-color);
    display: flex;
    align-items: center;
    gap: 4px;
}

.link-item:hover {
    text-decoration: underline;
}

/* Teaching List */
.teaching-list li {
    display: flex;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

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

.course-year {
    width: 120px;
    font-weight: 500;
    color: var(--text-tertiary);
    flex-shrink: 0;
}

.course-info {
    display: flex;
    flex-direction: column;
}

.course-info strong {
    color: var(--text-primary);
    margin-bottom: 2px;
}

.course-info span {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Footer */
.site-footer {
    padding: var(--spacing-xl) 0;
    border-top: 1px solid var(--border-color);
    margin-top: var(--spacing-xl);
    font-size: 0.9rem;
    color: var(--text-tertiary);
}

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

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

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

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

/* Responsive */
@media (max-width: 768px) {
    :root {
        --container-width: 100%;
        --spacing-xl: 3rem;
    }

    .paper-card {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }

    .paper-year {
        text-align: left;
        font-size: 0.8rem;
        margin-bottom: -4px;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .footer-content {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
}