:root {
    /* Academic / Minimalist Palette */
    --bg-color: #fafafa;
    /* Off-white, paper-like */
    --bg-secondary: #f4f4f4;
    /* Very subtle gray for sections */
    --text-primary: #222222;
    /* Near black for readability */
    --text-secondary: #555555;
    /* Dark gray */
    --accent: #8c2f39;
    /* Deep academic red/burgundy - dignified */
    --accent-hover: #b23a48;
    --border-color: #e0e0e0;
    --card-bg: #ffffff;

    --font-serif: 'Playfair Display', serif;
    --font-sans: 'Inter', sans-serif;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4 {
    font-family: var(--font-serif);
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
}

a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color 0.2s;
    border-bottom: 1px solid transparent;
}

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

/* Hero Section - Side-by-Side Academic Style */
.hero-section {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    position: relative;
    background-color: var(--bg-color);
}

.hero-content {
    max-width: 900px;
    width: 100%;
    padding: 2rem;
    display: grid;
    grid-template-columns: auto 1fr;
    /* Photo | Text */
    gap: 3rem;
    align-items: center;
}

.profile-container {
    margin-bottom: 0;
    /* Reset margin */
}

.profile-photo {
    width: 240px;
    /* x2 size */
    height: 240px;
    border-radius: 50%;
    object-fit: cover;
    filter: grayscale(100%);
    transition: filter 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.profile-photo:hover {
    filter: grayscale(0%);
}

.hero-text {
    text-align: left;
    /* Text aligned left */
}

.hero-text h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}

.hero-text .subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 400;
    font-family: var(--font-sans);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 1.5rem;
}

.divider {
    width: 40px;
    height: 1px;
    background-color: var(--text-primary);
    margin: 1.5rem 0;
    /* Left aligned margin */
}

.intro-note {
    font-size: 1.2rem;
    font-family: var(--font-serif);
    color: var(--text-secondary);
    margin: 0 0 2rem 0;
    /* Left aligned margin */
    max-width: 600px;
    font-style: normal;
}

.enter-button {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 0;
    font-size: 0.85rem;
    cursor: pointer;
    display: inline-flex;
    flex-direction: row;
    /* Horizontal for this layout */
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    font-family: var(--font-sans);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.enter-button:hover {
    color: var(--accent);
    transform: translateX(5px);
    /* Move right on hover */
}

/* Animations */
.fade-in {
    opacity: 0;
    transform: translateY(10px);
    animation: fadeInUp 1s forwards;
}

.delay-1 {
    animation-delay: 0.3s;
}

.delay-2 {
    animation-delay: 0.5s;
}

.delay-3 {
    animation-delay: 0.7s;
}

.delay-4 {
    animation-delay: 1.0s;
}

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

/* Main Content */
.hidden {
    display: none;
}

.visible {
    display: block;
    animation: fadeIn 0.8s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

/* Navigation - Minimalist */
#navbar {
    position: sticky;
    top: 0;
    background-color: rgba(250, 250, 250, 0.98);
    backdrop-filter: blur(5px);
    border-bottom: 1px solid var(--border-color);
    z-index: 100;
    padding: 1.25rem 0;
}

.nav-container {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.nav-logo {
    font-family: var(--font-serif);
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
    border: none;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 2.5rem;
}

.nav-links a {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-secondary);
    border: none;
}

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

/* Content Sections */
.content-section {
    padding: 6rem 1rem;
}

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

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1rem;
}

section h2 {
    font-size: 2rem;
    margin-bottom: 2.5rem;
    color: var(--text-primary);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
    display: inline-block;
}

/* About */
.content-block .lead {
    font-size: 1.4rem;
    margin-bottom: 1.5rem;
    font-family: var(--font-serif);
    color: var(--text-primary);
}

.content-block p {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

.social-links {
    display: flex;
    gap: 1.5rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.social-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    border: none;
}

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

/* Projects & Research Cards - Clean/Minimal */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    margin-top: 2rem;
}

.card {
    background: transparent;
    border: none;
    padding: 0;
}

.card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.card p {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.tags span {
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    padding: 0.2rem 0.6rem;
    font-size: 0.75rem;
    border-radius: 2px;
    font-family: var(--font-sans);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border: 1px solid var(--border-color);
}

/* Teaching List - Simple Table-like */
.teaching-list {
    list-style: none;
}

.teaching-list li {
    display: flex;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
    align-items: baseline;
}

.teaching-list .semester {
    width: 140px;
    flex-shrink: 0;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
}

.teaching-list .course {
    color: var(--text-primary);
    font-size: 1.05rem;
    font-family: var(--font-serif);
}

/* Footer */
footer {
    text-align: center;
    padding: 4rem 1rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    border-top: 1px solid var(--border-color);
}

/* Responsive */
@media (max-width: 768px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 1.5rem;
    }

    .hero-text {
        text-align: center;
    }

    .divider,
    .intro-note {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .grid-2 {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .nav-links {
        display: none;
        /* TODO: Add mobile menu if needed, or simple stack */
    }

    .teaching-list li {
        flex-direction: column;
        gap: 0.25rem;
    }
}