/* ===== CSS Variables ===== */
:root {
    --color-primary: #8C1515;
    --color-primary-dark: #6B0F0F;
    --color-text: #2D3748;
    --color-text-light: #4A5568;
    --color-text-muted: #718096;
    --color-background: #FFFFFF;
    --color-background-alt: #F7FAFC;
    --color-border: #E2E8F0;
    --color-accent: #2B6CB0;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --max-width: 1100px;
    --transition: 0.2s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-background);
}

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

a:hover {
    color: var(--color-primary-dark);
}

img {
    max-width: 100%;
    height: auto;
}

/* ===== Layout ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 80px 0;
}

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

.section-title {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 32px;
    color: var(--color-text);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 48px;
    height: 3px;
    background-color: var(--color-primary);
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.nav-logo {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    color: var(--color-text-light);
    font-size: 0.9375rem;
    font-weight: 500;
    transition: color var(--transition);
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
    padding: 140px 0 80px;
    background: linear-gradient(135deg, var(--color-background-alt) 0%, var(--color-background) 100%);
}

.hero-content {
    display: flex;
    align-items: center;
    gap: 64px;
}

.hero-text {
    flex: 1;
}

.hero h1 {
    font-size: 2.75rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: 16px;
}

.hero-affiliation {
    margin-bottom: 28px;
}

.affiliation-dept,
.affiliation-uni {
    display: block;
    color: var(--color-text-light);
}

.affiliation-dept {
    font-size: 1rem;
}

.affiliation-uni {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

.hero-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.hero-image {
    flex-shrink: 0;
}

.profile-placeholder {
    width: 240px;
    height: 360px;
    background: linear-gradient(135deg, var(--color-border) 0%, #CBD5E0 100%);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    font-size: 0.875rem;
    font-weight: 500;
}

.profile-placeholder img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 12px;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    font-size: 0.9375rem;
    font-weight: 500;
    border-radius: 8px;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    color: white;
}

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

.btn-secondary:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.btn .icon {
    width: 18px;
    height: 18px;
}

/* ===== About ===== */
.about-content p {
    max-width: 800px;
    margin-bottom: 16px;
    color: var(--color-text-light);
}

.about-content p:last-child {
    margin-bottom: 0;
}

/* ===== Research ===== */
.research-statement {
    max-width: 800px;
    margin-bottom: 40px;
}

.research-statement p {
    color: var(--color-text-light);
    margin-bottom: 16px;
}

.research-statement p:last-child {
    margin-bottom: 0;
}

.research-areas h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-text);
}

.keywords {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.keyword {
    display: inline-block;
    padding: 8px 16px;
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: 100px;
    font-size: 0.875rem;
    color: var(--color-text-light);
    transition: all var(--transition);
}

.keyword:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* ===== Publications ===== */
.publications-intro {
    color: var(--color-text-muted);
    margin-bottom: 24px;
}

.publications-scroll-container {
    max-height: 520px;
    overflow-y: auto;
    padding-right: 8px;
    border-radius: 12px;
}

/* Custom scrollbar styling */
.publications-scroll-container::-webkit-scrollbar {
    width: 6px;
}

.publications-scroll-container::-webkit-scrollbar-track {
    background: var(--color-background-alt);
    border-radius: 3px;
}

.publications-scroll-container::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 3px;
    transition: background var(--transition);
}

.publications-scroll-container::-webkit-scrollbar-thumb:hover {
    background: var(--color-text-muted);
}

/* Firefox scrollbar */
.publications-scroll-container {
    scrollbar-width: thin;
    scrollbar-color: var(--color-border) var(--color-background-alt);
}

.publications-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.publication-item {
    padding: 24px;
    background-color: var(--color-background-alt);
    border-radius: 12px;
    border: 1px solid var(--color-border);
    transition: all var(--transition);
}

.publication-item:hover {
    border-color: var(--color-primary);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.publication-year {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-primary);
    background-color: rgba(140, 21, 21, 0.1);
    padding: 4px 10px;
    border-radius: 4px;
    margin-bottom: 12px;
}

.publication-title {
    font-size: 1.0625rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 8px;
    line-height: 1.5;
}

.publication-title a {
    color: inherit;
}

.publication-title a:hover {
    color: var(--color-primary);
}

.publication-authors {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: 6px;
}

.publication-journal {
    font-size: 0.875rem;
    color: var(--color-text-light);
    font-style: italic;
}

.publication-links {
    margin-top: 12px;
    display: flex;
    gap: 12px;
}

.publication-link {
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-accent);
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.publication-link:hover {
    color: var(--color-primary);
}

.loading {
    text-align: center;
    padding: 40px;
    color: var(--color-text-muted);
}

.error-message {
    text-align: center;
    padding: 40px;
    color: var(--color-text-muted);
    background-color: var(--color-background-alt);
    border-radius: 12px;
}

/* ===== Contact ===== */
.contact-content {
    max-width: 600px;
}

.contact-info {
    display: grid;
    gap: 32px;
}

.contact-item h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.contact-item a {
    font-size: 1.0625rem;
}

.contact-item p {
    color: var(--color-text-light);
    line-height: 1.8;
}

.profile-links {
    display: flex;
    gap: 16px;
}

.profile-links a {
    font-size: 1rem;
}

/* ===== Footer ===== */
.footer {
    padding: 32px 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

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

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--color-background);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid var(--color-border);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all 0.3s ease;
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    .hero {
        padding: 100px 0 60px;
    }

    .hero-content {
        flex-direction: column-reverse;
        gap: 40px;
        text-align: center;
    }

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

    .hero-subtitle {
        font-size: 1.125rem;
    }

    .hero-links {
        justify-content: center;
    }

    .profile-placeholder {
        width: 180px;
        height: 210px;
    }

    .section {
        padding: 60px 0;
    }

    .section-title {
        font-size: 1.75rem;
    }

    .section-title::after {
        left: 50%;
        transform: translateX(-50%);
    }

    .about-content,
    .research-statement {
        text-align: center;
    }

    .keywords {
        justify-content: center;
    }

    .research-areas h3 {
        text-align: center;
    }

    .contact-content {
        text-align: center;
        margin: 0 auto;
    }

    .profile-links {
        justify-content: center;
    }

    .publication-item {
        padding: 20px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.75rem;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.875rem;
    }

    .publication-title {
        font-size: 1rem;
    }
}