/* Modern 2026 CSS with native variables, nesting, and logical properties */
:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #ffffff;
    --surface-color: #f8fafc;
    --nav-text: #000000; /* Force black navigation text */
    --text-main: #334155;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --radius: 12px;
    --font-sans: system-ui, -apple-system, sans-serif;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --primary: #60a5fa;
    --primary-hover: #93c5fd;
    --bg-color: #0f172a;
    --surface-color: #1e293b;
    --nav-text: #f1f5f9; /* Contrast in dark mode */
    --text-main: #f1f5f9;
    --text-muted: #94a3b8;
    --border-color: #334155;
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.7;
    margin: 0;
    padding: 0;
    transition: background-color var(--transition), color var(--transition);
}

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

a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

.container {
    width: min(100% - 2rem, 1100px);
    margin-inline: auto;
    padding-block: 2rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-block: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 2rem;
}

header h1 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 700;
}

.site-title .subtitle {
    margin: 0.25rem 0 0 0;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.theme-toggle {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-family: inherit;
    font-weight: 500;
    transition: all var(--transition);
}

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

.layout-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
}

@media (min-width: 768px) {
    .layout-grid {
        grid-template-columns: 1fr 280px;
    }
}

section {
    margin-block-end: 3rem;
}

section p {
    margin-block-end: 1.25rem;
}

/* Sidebar Styles */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    position: sticky;
    top: 2rem;
    align-self: start;
}

.sidebar-widget {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
    text-align: center;
}

.sidebar-widget.links-widget {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.profile-image-widget img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
}

.linkedin-logo { width: 130px; }
.facebook-logo { width: 130px; }
.rg-logo { width: 190px; }
.scholar-logo { width: 120px; }
.wos-logo { width: 130px; }

.orcid-widget a {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    font-family: monospace;
    color: var(--text-main);
    word-break: break-all;
}

.orcid-widget img {
    width: 16px;
    height: 16px;
}

.image-gallery {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-block: 2rem;
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
}

.image-gallery img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    object-fit: cover;
}

.image-gallery figcaption {
    width: 100%;
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 1rem;
}

figure.media-highlight {
    margin: 2rem 0;
    text-align: center;
}

figure.media-highlight img {
    max-width: 100%;
    width: 75%;
    border-radius: var(--radius);
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
}

figure.media-highlight figcaption {
    margin-top: 0.75rem;
    font-size: 0.875rem;
    font-style: italic;
    color: var(--text-muted);
}

.publications h3 {
    margin-block: 2rem 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.publications ol {
    padding-left: 1.5rem;
}

.publications ol li {
    margin-bottom: 1rem;
}

.publications ol li strong {
    color: var(--primary);
}

hr {
    border: 0;
    height: 1px;
    background: var(--border-color);
    margin-block: 3rem;
}

.update-notice {
    text-align: right;
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Header Controls & Hover Popup Menu (Modernized) */
.header-controls {
    display: flex;
    align-items: center;
    gap: 2rem;
}

/* Main Nav Wrapper */
.main-nav {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-link.home-link {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--nav-text);
    text-decoration: none;
    transition: color var(--transition);
}

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

.nav-link.home-link-2 {
    font-size: 1.1rem;
    font-weight: 400;
    color: var(--nav-text);
    text-decoration: none;
    transition: color var(--transition);
}

.nav-link.home-link-2:hover {
    color: var(--primary-hover);
    text-decoration: none;
}

.nav-menu-container {
    position: relative;
    display: inline-block;
    padding-bottom: 1rem; /* Invisible bridge to keep menu open while mouse travels */
    margin-bottom: -1rem;
}

.popup-btn {
    background: transparent;
    border: none;
    color: var(--nav-text);
    font-size: 1.1rem;
    font-family: inherit;
    font-weight: 400; /* Regular weight for 'About me' */
    cursor: pointer;
    padding: 0.5rem 0;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.popup-btn .arrow {
    font-size: 0.8rem;
    transition: transform var(--transition);
}

/* Trigger menu and rotate arrow on HOVER or FOCUS */
.nav-menu-container:hover .arrow,
.nav-menu-container:focus-within .arrow {
    transform: rotate(180deg);
}

.popup-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px); /* Start slightly down for slide-up animation */
    margin-top: 0;
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    list-style: none;
    padding: 0.5rem 0;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1); /* Deep, soft modern shadow */
    min-width: 180px;
    z-index: 100;
    
    /* Animation states */
    opacity: 0;
    visibility: hidden;
    pointer-events: none; /* Prevents invisible menu from blocking clicks */
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275); /* Snappy slide-up bounce */
}

/* Show menu on HOVER or FOCUS */
.nav-menu-container:hover .popup-menu,
.nav-menu-container:focus-within .popup-menu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
}

.popup-menu li a {
    display: block;
    padding: 0.75rem 1.5rem;
    color: var(--text-main);
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.2s ease, color 0.2s ease;
}

.popup-menu li:last-child a {
    border-bottom: none;
}

.popup-menu li a:hover {
    background: var(--bg-color);
    text-decoration: none;
    color: var(--primary);
}

/* Education Cards Styling */
.education-timeline {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-top: 1.5rem;
    margin-bottom: 2.5rem;
}

.edu-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    transition: transform var(--transition), box-shadow var(--transition);
}

.edu-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.edu-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.edu-degree {
    margin: 0;
    font-size: 1.3rem;
    color: var(--primary);
}

.edu-years {
    font-weight: 600;
    color: var(--text-muted);
    background: var(--bg-color);
    padding: 0.35rem 0.85rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    border: 1px solid var(--border-color);
}

.edu-institution {
    margin: 0 0 1.25rem 0;
    font-weight: 600;
    font-size: 1.05rem;
    color: var(--text-main);
}

.edu-details {
    border-top: 1px solid var(--border-color);
    padding-top: 1.25rem;
}

.edu-details p {
    margin: 0 0 0.5rem 0;
    font-size: 0.95rem;
}

.edu-details p:last-child {
    margin-bottom: 0;
}

.edu-details strong {
    color: var(--text-main);
    font-weight: 700;
}

/* Memberships Cards Styling */
.memberships-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-top: 1.5rem;
    margin-bottom: 2.5rem;
}

@media (min-width: 640px) {
    .memberships-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.membership-card {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    transition: transform var(--transition), box-shadow var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.membership-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.membership-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.membership-card a {
    color: var(--text-main);
    text-decoration: none;
    transition: color var(--transition);
}

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

.membership-role {
    display: inline-block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--primary);
    background: var(--bg-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    border: 1px solid var(--border-color);
    align-self: flex-start;
    margin-top: 1rem;
}