/* =====================
   Header
   ===================== */
.header {
    background-color: white;
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all var(--transition-normal);
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 2rem;
}

.header.scrolled .header-container {
    padding: 0.7rem 2rem;
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    justify-self: end;
}

.nav {
    justify-self: center;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    overflow: hidden;
    background-color: var(--color-gray-200);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-primary);
    font-weight: bold;
}

.nav ul {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 1.5rem;
}

.nav a {
    text-decoration: none;
    color: var(--color-gray-700);
    font-weight: 500;
    padding: 0.5rem 0.2rem;
    position: relative;
    transition: color var(--transition-fast);
}

.nav a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--color-secondary);
    transition: width var(--transition-normal);
}

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

.nav a:hover::after {
    width: 100%;
}

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

.nav a.active::after {
    width: 100%;
    background-color: var(--color-secondary);
}

.menu-button {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--color-primary);
    cursor: pointer;
}

/* Header Responsive */
@media (max-width: 1024px) {
    .header-container {
        grid-template-columns: 1fr auto;
        padding: 1rem;
    }

    .nav {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--color-gray-100);
        box-shadow: var(--shadow-md);
        padding: 1rem;
        display: none;
        transition: all var(--transition-normal);
    }

    .nav.open {
        display: block;
    }

    .menu-button {
        display: inline-flex;
        align-items: center;
        justify-content: center;
    }

    .nav ul {
        flex-direction: column;
        gap: 1rem;
    }

    .nav a.active::after {
        width: 30%;
    }

    .header.scrolled .header-container {
        padding: 0.7rem 1rem;
    }
}

@media (max-width: 768px) {
    .header-actions {
        gap: var(--space-sm);
    }
}

@media (max-width: 480px) {
    .logo span {
        display: none;
    }

    .logo {
        gap: 0.5rem;
    }

    .logo-icon {
        width: 36px;
        height: 36px;
        font-size: 0.9rem;
    }
}

/* =====================
   Theme Toggle
   ===================== */
.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2rem;
    padding: var(--space-sm);
    border-radius: 50%;
    transition: background-color var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background-color: var(--color-gray-200);
}

/* =====================
   Footer
   ===================== */
.footer {
    background-color: var(--color-primary);
    color: white;
    padding: var(--space-lg) 0 var(--space-md);
    margin-top: var(--space-xxl);
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-xl);
}

.footer-section h3 {
    color: white;
    font-size: 1.2rem;
    margin-top: 0;
    margin-bottom: var(--space-md);
    position: relative;
    padding-bottom: var(--space-sm);
}

.footer-section h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 2px;
    background-color: var(--color-secondary);
}

.footer-section p {
    margin: var(--space-sm) 0;
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.8);
}

.footer-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-section ul li {
    margin-bottom: var(--space-sm);
}

.footer-section a {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    transition: all var(--transition-fast);
    padding: 0.2rem 0;
    display: inline-block;
    font-weight: 500;
}

.footer-section a:hover {
    color: var(--color-secondary);
    transform: translateX(3px);
}

.footer .social-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-md);
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-lg) var(--space-lg) 0;
    text-align: center;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: var(--space-lg);
}

.footer-bottom p {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.6);
}

@media (max-width: 768px) {
    .footer-container {
        grid-template-columns: 1fr;
        gap: var(--space-lg);
        padding: 0 var(--space-md);
    }

    .footer-bottom {
        padding: var(--space-lg) var(--space-md) 0;
    }
}

/* =====================
   Publication Card
   ===================== */
.publication-card {
    background-color: white;
    border-radius: var(--border-radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    display: flex;
    position: relative;
}

.publication-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.publication-year {
    background-color: var(--color-primary);
    color: white;
    padding: var(--space-md);
    min-width: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.2rem;
}

.publication-content {
    padding: var(--space-lg);
    flex: 1;
}

.publication-card h3 {
    margin-top: 0;
    margin-bottom: var(--space-sm);
    color: var(--color-primary);
    transition: color var(--transition-fast);
}

.publication-card:hover h3 {
    color: var(--color-secondary);
}

.publication-card .authors {
    color: var(--color-gray-700);
    font-style: italic;
    margin-bottom: var(--space-sm);
}

.publication-card .journal {
    color: var(--color-gray-600);
    font-weight: 600;
    margin-bottom: var(--space-md);
}

.publication-card .doi {
    color: var(--color-gray-600);
    margin-bottom: var(--space-md);
    font-size: 0.9rem;
}

.publication-card .doi a {
    color: var(--color-primary);
    text-decoration: underline;
}

.abstract-container {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal);
}

.abstract-container.expanded {
    max-height: 300px;
    overflow-y: auto;
}

.abstract {
    background-color: var(--color-gray-100);
    padding: var(--space-md);
    border-radius: var(--border-radius-sm);
    color: var(--color-gray-700);
    margin: var(--space-md) 0;
    line-height: 1.6;
}

.publication-actions {
    display: flex;
    gap: var(--space-md);
    margin-top: var(--space-md);
}

@media (max-width: 768px) {
    .publication-card {
        flex-direction: column;
    }

    .publication-year {
        width: 100%;
        padding: var(--space-sm);
    }
}

/* =====================
   Animated Elements
   ===================== */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--transition-normal), transform var(--transition-normal);
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

.animate-on-scroll.fade-in {
    transform: translateY(0);
}

.animate-on-scroll.slide-up {
    transform: translateY(40px);
}

.animate-on-scroll.slide-left {
    transform: translateX(40px);
}

.animate-on-scroll.slide-right {
    transform: translateX(-40px);
}

.animate-on-scroll.zoom-in {
    transform: scale(0.9);
}

.animate-on-scroll.visible.slide-up,
.animate-on-scroll.visible.slide-left,
.animate-on-scroll.visible.slide-right {
    transform: translate(0);
}

.animate-on-scroll.visible.zoom-in {
    transform: scale(1);
}