/* ============================================
   Academic Webpage Stylesheet
   Clean, professional design for theoretical physics
   ============================================ */

/* ============================================
   CSS Variables & Reset
   ============================================ */
:root {
    --primary-color: #1a1a1a;
    --secondary-color: #4a4a4a;
    --accent-color: #5b9bd5;
    --accent-light: #e8f2f9;
    --background-color: #ffffff;
    --alt-background: #f7fafc;
    --border-color: #d4e4f0;
    --max-width: 900px;
    --spacing-unit: 1.5rem;
}

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

/* ============================================
   Typography
   ============================================ */
html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Georgia', 'Times New Roman', serif;
    line-height: 1.7;
    color: var(--primary-color);
    background-color: var(--background-color);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    font-weight: 600;
    line-height: 1.3;
    color: var(--primary-color);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

/* ============================================
   Links
   ============================================ */
a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: #4a8cc7;
    text-decoration: underline;
}

/* ============================================
   Layout Containers
   ============================================ */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

.section {
    padding: 4rem 0;
}

.section-alt {
    background-color: var(--alt-background);
}

.section-title {
    margin-bottom: 2rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-color);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--secondary-color);
}

.subsection-title {
    margin-top: 2rem;
    margin-bottom: 1rem;
    font-size: 1.25rem;
    color: var(--secondary-color);
}

/* ============================================
   Navigation
   ============================================ */
.nav {
    position: sticky;
    top: 0;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: box-shadow 0.3s ease;
}

.nav-scrolled {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.nav-link {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav-link:hover {
    color: var(--accent-color);
    text-decoration: none;
}

/* ============================================
   Header/Hero Section
   ============================================ */
.header {
    padding: 3.5rem 0 1.5rem;
    text-align: left;
    background-color: var(--background-color);
    border-bottom: 1px solid var(--border-color);
}

.name {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.title {
    font-size: 1.05rem;
    color: var(--secondary-color);
    margin-bottom: 0.25rem;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-weight: 400;
}

.institution {
    font-size: 1.05rem;
    color: var(--secondary-color);
    margin-bottom: 0.75rem;
    font-weight: 400;
}

.tagline {
    font-size: 0.95rem;
    color: var(--secondary-color);
    font-style: normal;
    max-width: 650px;
    margin: 0.75rem 0 0;
    line-height: 1.6;
}

/* ============================================
   About Section
   ============================================ */
#about {
    padding-top: 2rem;
}

.about-content p {
    margin-bottom: 1.25rem;
}

.interests-list {
    list-style-position: inside;
    margin-top: 0.75rem;
}

.interests-list li {
    margin-bottom: 0.5rem;
    padding-left: 0.5rem;
}

/* ============================================
   Research Section - Featured Papers
   ============================================ */
.research-intro {
    margin-bottom: 2.5rem;
    font-size: 1.05rem;
    color: var(--secondary-color);
}

.paper-featured {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-bottom: 3rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--border-color);
}

.paper-featured:last-of-type {
    border-bottom: none;
    padding-bottom: 0;
}

.paper-content {
    order: 1;
}

.paper-title {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.paper-title a {
    color: var(--primary-color);
    text-decoration: none;
}

.paper-title a:hover {
    color: var(--accent-color);
    text-decoration: underline;
}

.paper-authors {
    font-size: 0.95rem;
    color: var(--secondary-color);
    margin-bottom: 0.25rem;
}

.paper-authors strong {
    color: var(--primary-color);
}

.paper-venue {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-style: italic;
    margin-bottom: 1rem;
}

.paper-description {
    font-size: 1rem;
    line-height: 1.7;
}

.paper-figure {
    order: 2;
    text-align: center;
    border: none;
}

.paper-figure img {
    width: 100%;
    height: auto;
    border: none;
    outline: none;
}

.figure-caption {
    margin-top: 0.5rem;
    font-size: 0.875rem;
    color: var(--secondary-color);
    font-style: italic;
}

/* ============================================
   Publications Section
   ============================================ */
.publications-intro {
    margin-bottom: 2rem;
    padding: 1rem 1.5rem;
    background-color: var(--accent-light);
    border-left: 3px solid var(--accent-color);
}

.publications-intro p {
    margin: 0;
}

.paper-list {
    list-style-position: outside;
    padding-left: 2rem;
    counter-reset: item;
}

.paper-item {
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.paper-title-inline a {
    color: var(--primary-color);
    font-weight: 500;
}

.paper-title-inline a:hover {
    color: var(--accent-color);
}

.paper-authors-inline {
    font-size: 0.95rem;
    color: var(--secondary-color);
}

.paper-authors-inline strong {
    color: var(--primary-color);
}

.paper-venue-inline {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-style: italic;
}

/* ============================================
   Contact Section
   ============================================ */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 2rem;
}

.contact-item {
    padding: 1.5rem;
    background-color: var(--background-color);
}

.contact-label {
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    color: var(--secondary-color);
}

.contact-item p {
    margin: 0;
    line-height: 1.8;
}

.contact-item a {
    display: inline-block;
    margin: 0.25rem 0;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    background-color: var(--alt-background);
}

.footer p {
    font-size: 0.875rem;
    color: var(--secondary-color);
}

/* ============================================
   Responsive Design - Tablet
   ============================================ */
@media (min-width: 768px) {
    .paper-featured {
        grid-template-columns: 1fr 1fr;
    }
    
    .paper-content {
        order: 1;
    }
    
    .paper-figure {
        order: 2;
    }
    
    .contact-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ============================================
   Responsive Design - Desktop
   ============================================ */
@media (min-width: 1024px) {
    .paper-featured {
        grid-template-columns: 1fr 1fr;
    }
    
    .contact-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ============================================
   Responsive Design - Mobile
   ============================================ */
@media (max-width: 767px) {
    html {
        font-size: 15px;
    }
    
    .container {
        padding: 0 1.5rem;
    }
    
    .section {
        padding: 3rem 0;
    }
    
    .header {
        padding: 2.5rem 0 2rem;
    }
    
    .name {
        font-size: 1.75rem;
    }
    
    .title {
        font-size: 1rem;
    }
    
    .nav-container {
        gap: 1rem;
        padding: 0.75rem 1.5rem;
    }
    
    .nav-link {
        font-size: 0.9rem;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
    
    .paper-featured {
        margin-bottom: 2rem;
        padding-bottom: 2rem;
    }
    
    .contact-item {
        padding: 1rem;
    }
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
    .nav {
        display: none;
    }
    
    .section {
        page-break-inside: avoid;
    }
    
    a {
        color: var(--primary-color);
        text-decoration: underline;
    }
    
    a[href^="http"]:after {
        content: " (" attr(href) ")";
        font-size: 0.8em;
    }
}