/* ===== CSS Variables ===== */
:root {
    --font-serif: 'Crimson Pro', Georgia, serif;
    --font-sans: 'Source Sans 3', -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    
    --color-bg: #faf9f7;
    --color-bg-alt: #f3f1ed;
    --color-text: #2c2c2c;
    --color-text-muted: #636363;
    --color-accent: #1a5f7a;
    --color-accent-hover: #134b61;
    --color-border: #e0ddd8;
    --color-highlight: #e8f4f8;
    
    --max-width: 720px;
    --spacing-unit: 1rem;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: 17px;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

/* ===== Layout ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 calc(var(--spacing-unit) * 1.5);
}

/* ===== Header & Navigation ===== */
header {
    padding: calc(var(--spacing-unit) * 2) 0;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: calc(var(--spacing-unit) * 3);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: var(--spacing-unit);
}

.nav-name {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: calc(var(--spacing-unit) * 1.5);
}

.nav-links a {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.2s ease;
}

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

/* ===== Main Content ===== */
main {
    padding-bottom: calc(var(--spacing-unit) * 4);
}

.section {
    margin-bottom: calc(var(--spacing-unit) * 4);
}

/* ===== Typography ===== */
h1, h2, h3 {
    font-family: var(--font-serif);
    font-weight: 600;
    line-height: 1.3;
    letter-spacing: -0.02em;
}

h1 {
    font-size: 2.25rem;
    margin-bottom: calc(var(--spacing-unit) * 0.75);
}

h2 {
    font-size: 1.5rem;
    margin-bottom: calc(var(--spacing-unit) * 1.5);
    padding-bottom: calc(var(--spacing-unit) * 0.5);
    border-bottom: 2px solid var(--color-text);
    display: inline-block;
}

h3 {
    font-size: 1.15rem;
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

p {
    margin-bottom: var(--spacing-unit);
}

a {
    color: var(--color-accent);
    text-decoration-thickness: 1px;
    text-underline-offset: 2px;
    transition: color 0.2s ease;
}

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

/* ===== Intro Section ===== */
.intro {
    padding: calc(var(--spacing-unit) * 2) 0;
}

.highlight {
    color: var(--color-accent);
}

.tagline {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: calc(var(--spacing-unit) * 1.5);
    letter-spacing: -0.01em;
}

.bio {
    font-size: 1.05rem;
    color: var(--color-text);
}

/* ===== Papers ===== */
.papers {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 2);
}

.paper {
    padding: calc(var(--spacing-unit) * 1.5);
    background: var(--color-bg-alt);
    border-radius: 6px;
    border-left: 3px solid var(--color-accent);
}

.paper h3 {
    color: var(--color-text);
}

.paper .authors {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    margin-bottom: calc(var(--spacing-unit) * 0.25);
}

.paper .venue {
    font-size: 0.9rem;
    font-style: italic;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-unit);
}

.paper .abstract {
    font-size: 0.95rem;
    line-height: 1.65;
}

.paper-links {
    display: flex;
    gap: var(--spacing-unit);
    margin-top: var(--spacing-unit);
    padding-top: var(--spacing-unit);
    border-top: 1px solid var(--color-border);
}

.paper-links a {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    text-decoration: none;
    padding: 0.25rem 0.6rem;
    background: var(--color-bg);
    border-radius: 4px;
    transition: background 0.2s ease;
}

.paper-links a:hover {
    background: var(--color-highlight);
}

/* ===== Writings ===== */
.section-intro {
    color: var(--color-text-muted);
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

.writings-list {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 0.5);
}

.writing-item {
    display: block;
    padding: calc(var(--spacing-unit) * 1.25);
    text-decoration: none;
    border-radius: 6px;
    transition: background 0.2s ease;
}

.writing-item:hover {
    background: var(--color-bg-alt);
}

.writing-title {
    display: block;
    font-family: var(--font-serif);
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: calc(var(--spacing-unit) * 0.25);
}

.writing-date {
    display: block;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

.writing-preview {
    display: block;
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.5;
}

/* ===== Contact ===== */
.contact-links {
    list-style: none;
    margin-top: var(--spacing-unit);
}

.contact-links li {
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

.contact-label {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-right: calc(var(--spacing-unit) * 0.5);
}

/* ===== Footer ===== */
footer {
    padding: calc(var(--spacing-unit) * 2) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

footer p {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin: 0;
}

/* ===== MathJax Styling ===== */
mjx-container {
    font-size: 105% !important;
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
    body {
        font-size: 16px;
    }
    
    h1 {
        font-size: 1.75rem;
    }
    
    nav {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .nav-links {
        gap: var(--spacing-unit);
    }
}

/* ===== Selection ===== */
::selection {
    background: var(--color-highlight);
}

/* ===== Print ===== */
@media print {
    header, footer, .paper-links {
        display: none;
    }
    
    .paper {
        break-inside: avoid;
    }
}