/* ============================================================
   Design tokens
   ============================================================ */
:root {
    --color-ink: #1a201e;
    --color-ink-soft: #454f4c;
    --color-muted: #707876;
    --color-paper: #f5f6f5;
    --color-surface: #ffffff;
    --color-border: #e5e9e7;

    --color-primary: #10665c;
    --color-primary-dark: #0b493f;
    --color-primary-tint: #e3efec;

    --color-accent: #ef6c4d;
    --color-accent-dark: #d24f30;
    --color-accent-tint: #fdece6;

    --font-heading: 'Space Grotesk', 'Montserrat', sans-serif;
    --font-nav: 'Montserrat', sans-serif;
    --font-body: 'Inter', sans-serif;

    --radius-md: 12px;
    --radius-lg: 18px;
    --shadow-sm: 0 1px 2px rgba(17, 24, 22, 0.04), 0 2px 10px rgba(17, 24, 22, 0.05);
    --shadow-md: 0 10px 30px rgba(17, 24, 22, 0.09);

    --max-width: 1200px;
}

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

body {
    font-family: var(--font-body);
    line-height: 1.6;
    color: var(--color-ink);
    background-color: var(--color-paper);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--color-ink);
}

nav, .subtitle {
    font-family: var(--font-nav);
}

p {
    line-height: 1.8;
}

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

.subtitle {
    letter-spacing: 0.02em;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================================================
   Header / navigation
   ============================================================ */
header {
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 22px 0;
    margin-bottom: 40px;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.site-brand {
    display: block;
}

.site-brand h1 {
    margin-bottom: 4px;
    font-size: 1.5rem;
    line-height: 1.25;
    font-weight: 600;
}

.site-brand h1 a {
    color: var(--color-ink);
    text-decoration: none;
}

.site-brand h1 a:hover {
    color: var(--color-primary);
}

.site-subtitle {
    font-family: var(--font-nav);
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--color-muted);
}

@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        align-items: flex-start;
    }
    .site-brand {
        margin-bottom: 15px;
    }
}

nav {
    display: flex;
    align-items: center;
}

nav ul {
    list-style: none;
    display: flex;
    margin: 0;
    flex-wrap: wrap;
}

nav ul li {
    margin-right: 24px;
    margin-bottom: 0;
}

nav ul li:last-child {
    margin-right: 0;
}

nav ul li a {
    text-decoration: none;
    color: var(--color-ink-soft);
    font-weight: 500;
    font-size: 0.95rem;
    letter-spacing: 0.01em;
    padding: 5px 0;
    transition: all 0.3s ease;
    position: relative;
}

nav ul li a:hover, nav ul li a.active {
    color: var(--color-primary);
}

nav ul li a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--color-accent);
    transition: width 0.3s ease;
}

nav ul li a:hover::after, nav ul li a.active::after {
    width: 100%;
}

.menu-toggle {
    display: none;
    cursor: pointer;
    font-size: 1.5rem;
    color: var(--color-ink);
}

@media screen and (max-width: 768px) {
    .menu-toggle {
        display: block;
    }
    nav ul {
        display: none;
        flex-direction: column;
        width: 100%;
        text-align: center;
        position: absolute;
        top: 60px;
        left: 0;
        background-color: var(--color-surface);
        box-shadow: var(--shadow-sm);
        z-index: 20;
    }
    nav ul.show {
        display: flex;
    }
    nav ul li {
        margin: 0;
        padding: 10px 0;
        width: 100%;
    }
}

/* ============================================================
   Layout
   ============================================================ */
.content-wrapper {
    display: flex;
    gap: 30px;
}

.main-content {
    flex: 1;
    min-width: 0;
}

@media (max-width: 900px) {
    .content-wrapper {
        flex-direction: column;
    }
}

/* ============================================================
   Profile sidebar
   ============================================================ */
.profile-sidebar {
    flex: 0 0 280px;
    background-color: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: 25px;
    height: fit-content;
    position: sticky;
    top: 30px;
}

@media (max-width: 900px) {
    .profile-sidebar {
        position: static;
        max-width: 100%;
        margin-bottom: 30px;
    }
}

.profile-image {
    text-align: center;
    margin-bottom: 20px;
}

.profile-image img {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--color-primary);
}

.profile-info h2 {
    text-align: center;
    margin-bottom: 10px;
    font-size: 1.3rem;
}

.subtitle {
    color: var(--color-muted);
    font-size: 0.92em;
    margin-bottom: 8px;
    text-align: center;
}

.contact-details {
    margin: 10px 0;
}

.contact-details p {
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.contact-details i {
    width: 20px;
    color: var(--color-primary);
    margin-right: 10px;
}

.contact-details a {
    text-decoration: none;
    color: var(--color-ink-soft);
}

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

.social-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 20px;
}

.social-links a {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 35px;
    height: 35px;
    margin: 4px 5px;
    color: var(--color-ink-soft);
    font-size: 1.1em;
    background-color: var(--color-paper);
    border-radius: 50%;
    transition: all 0.3s ease;
}

.social-links a:hover {
    color: #fff;
    background-color: var(--color-primary);
    transform: translateY(-3px);
}

/* Compact sidebar variant (used on every page except Home) */
.profile-sidebar--compact {
    flex: 0 0 190px;
    padding: 20px 16px;
    text-align: center;
}

.profile-image-compact {
    margin-bottom: 10px;
}

.profile-image-compact img {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--color-primary);
}

.profile-name-compact {
    font-size: 1rem;
    margin-bottom: 12px;
}

.profile-sidebar--compact .social-links {
    margin-top: 0;
}

.profile-sidebar--compact .social-links a {
    width: 30px;
    height: 30px;
    font-size: 0.95em;
    margin: 3px 4px;
}

@media (max-width: 900px) {
    .profile-sidebar--compact {
        flex: 0 0 auto;
    }
}

.sidebar-widget {
    margin-top: 22px;
    padding-top: 18px;
    border-top: 1px solid var(--color-border);
    text-align: left;
}

.sidebar-widget-title {
    font-family: var(--font-nav);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: 10px;
}

.sidebar-widget-list {
    list-style: none;
    display: flex;
    flex-direction: column;
}

.sidebar-widget-list li {
    padding: 10px 0;
    border-bottom: 1px solid var(--color-border);
}

.sidebar-widget-list li:first-child {
    padding-top: 0;
}

.sidebar-widget-list li:last-child {
    padding-bottom: 0;
    border-bottom: none;
}

.sidebar-widget-list a {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    line-height: 1.4;
    color: var(--color-ink);
    text-decoration: none;
    transition: color 0.25s ease;
}

.sidebar-widget-list a:hover {
    color: var(--color-primary);
}

.sidebar-widget-date {
    display: block;
    margin-top: 4px;
    font-family: var(--font-nav);
    font-size: 0.68rem;
    letter-spacing: 0.02em;
    color: var(--color-muted);
}

/* ============================================================
   Shared "card" section style
   ============================================================ */
.home-content,
.cv-section,
.publications-section,
.certificates-section,
.project-details,
.projects-section,
.portfolio-section,
.blog-section,
.post-detail {
    background-color: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: 30px;
    margin-bottom: 30px;
}

.home-content h2,
.cv-section h2,
.publications-section h2,
.certificates-section h2,
.project-details h2,
.projects-section h2,
.portfolio-section h2,
.blog-section h2 {
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--color-primary);
}

.journey, .research-interests {
    margin-bottom: 30px;
}

.journey h3, .research-interests h3 {
    color: var(--color-primary);
    margin-bottom: 15px;
}

.journey p {
    margin-bottom: 15px;
    line-height: 1.8;
}

.research-interests ul {
    list-style: none;
    padding-left: 0;
}

.intro-paragraph {
    font-size: 1.15rem;
    line-height: 1.7;
    color: var(--color-ink);
    margin-bottom: 2rem;
    border-left: 3px solid var(--color-accent);
    padding-left: 1rem;
    font-weight: 300;
    max-width: 95%;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.intro-paragraph {
    animation: fadeIn 0.8s ease-in-out;
}

/* Quick stats line at the bottom of Home */
.quick-stats-line {
    display: flex;
    flex-wrap: wrap;
    gap: 6px 20px;
    margin-top: 30px;
    padding-top: 18px;
    border-top: 1px solid var(--color-border);
    font-family: var(--font-nav);
    font-size: 0.8rem;
    color: var(--color-muted);
}

/* Pull-quote callout inside Journey */
.home-callout {
    margin: 6px 0 4px;
    padding: 16px 22px;
    background-color: var(--color-primary-tint);
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius-md);
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--color-primary-dark);
}

/* Research interests as an even two-column grid */
.interest-chips {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.interest-chips li {
    display: flex;
    align-items: center;
    gap: 10px;
    background-color: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    margin-bottom: 0;
    font-size: 0.9rem;
    color: var(--color-ink-soft);
    transition: all 0.25s ease;
}

.interest-chips li:hover {
    border-color: var(--color-primary);
    color: var(--color-primary-dark);
}

.interest-chips i {
    flex-shrink: 0;
    width: 20px;
    text-align: center;
    color: var(--color-primary);
    font-size: 1em;
}

@media (max-width: 640px) {
    .interest-chips {
        grid-template-columns: 1fr;
    }
}

/* ============================================================
   404 page
   ============================================================ */
.error-section {
    background-color: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: 60px 30px;
    margin-bottom: 30px;
    text-align: center;
}

.error-code {
    font-family: var(--font-heading);
    font-size: 4.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 8px;
}

.error-section h2 {
    margin-bottom: 12px;
}

.error-message {
    color: var(--color-ink-soft);
    margin-bottom: 25px;
}

/* ============================================================
   Shared: back link
   ============================================================ */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--color-primary);
    text-decoration: none;
    font-family: var(--font-nav);
    font-size: 0.9rem;
    margin-bottom: 20px;
}

.back-link:hover {
    text-decoration: underline;
}

/* ============================================================
   Footer
   ============================================================ */
footer {
    background-color: var(--color-primary-dark);
    color: rgba(255, 255, 255, 0.85);
    padding: 34px 0 26px;
    margin-top: 50px;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    text-align: center;
}

.footer-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px 22px;
    font-family: var(--font-nav);
}

.footer-nav a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    font-size: 0.85rem;
    letter-spacing: 0.01em;
    transition: color 0.25s ease;
}

.footer-nav a:hover {
    color: #fff;
}

.footer-copyright {
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.5);
}

/* ============================================================
   CV page (text version, still used above/around the flipbook)
   ============================================================ */
.cv-download {
    margin-bottom: 25px;
    text-align: center;
}

.cv-download-btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background-color: var(--color-primary);
    color: white;
    padding: 10px 20px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(16, 102, 92, 0.3);
}

.cv-download-btn:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(16, 102, 92, 0.4);
}

/* ============================================================
   Publications
   ============================================================ */
.publication-filters,
.certificate-filters {
    margin-bottom: 25px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.filter-btn {
    background-color: var(--color-paper);
    border: none;
    padding: 8px 15px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.85em;
    font-family: var(--font-nav);
    color: var(--color-ink-soft);
    transition: all 0.3s ease;
}

.filter-btn:hover, .filter-btn.active {
    background-color: var(--color-primary);
    color: white;
}

.filter-count {
    margin-left: 4px;
    font-size: 0.88em;
    opacity: 0.7;
}

.publication-item {
    display: flex;
    margin-bottom: 2.5rem;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 2rem;
}

.publication-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.publication-year {
    min-width: 60px;
    font-weight: bold;
    color: var(--color-primary);
    margin-right: 1rem;
}

.publication-journal-cover {
    width: 100px;
    margin-right: 1.5rem;
    flex-shrink: 0;
}

.publication-journal-cover img {
    width: 100%;
    border-radius: 4px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease;
}

.publication-journal-cover img:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.publication-content {
    flex: 1;
}

.publication-content h3 {
    margin-bottom: 5px;
    font-size: 1.15em;
}

.publication-authors {
    color: var(--color-ink-soft);
    margin-bottom: 5px;
}

.publication-journal {
    color: var(--color-muted);
    font-style: italic;
    margin-bottom: 10px;
}

.publication-links {
    margin-bottom: 10px;
}

.publication-link {
    display: inline-block;
    background-color: var(--color-paper);
    padding: 5px 12px;
    border-radius: 4px;
    text-decoration: none;
    color: var(--color-ink);
    margin-right: 10px;
    font-size: 0.9em;
    transition: all 0.3s ease;
}

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

.abstract-toggle {
    background: none;
    border: none;
    color: var(--color-primary);
    cursor: pointer;
    padding: 0;
    font-size: 0.9em;
}

.abstract-toggle i {
    margin-left: 5px;
    transition: transform 0.3s ease;
}

.abstract-content {
    display: none;
    margin-top: 10px;
    padding: 12px 15px;
    background-color: var(--color-paper);
    border-radius: 6px;
}

.abstract-content.show {
    display: block;
}

@media (max-width: 768px) {
    .publication-item {
        flex-direction: column;
    }
    .publication-journal-cover {
        width: 80px;
        margin-bottom: 1rem;
        align-self: center;
    }
    .publication-year {
        margin-bottom: 0.5rem;
    }
}

/* ============================================================
   Certificates
   ============================================================ */
.certificate-item {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 22px;
    margin-bottom: 20px;
    transition: all 0.3s ease;
}

.certificate-item:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
    transform: translateY(-2px);
}

.certificate-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 8px;
    gap: 10px;
}

.certificate-title {
    display: flex;
    align-items: flex-start;
    gap: 14px;
}

.certificate-logo-frame {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    flex-shrink: 0;
    padding: 7px;
    background-color: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: 8px;
}

.provider-logo {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.certificate-title-text {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.certificate-title h4 {
    font-weight: 600;
    margin: 0;
    font-size: 1.05em;
    line-height: 1.4;
}

.certificate-category-tag {
    display: inline-block;
    align-self: flex-start;
    font-family: var(--font-nav);
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    color: var(--color-primary-dark);
    background-color: var(--color-primary-tint);
    padding: 2px 10px;
    border-radius: 20px;
}

.certificate-date {
    color: var(--color-muted);
    font-size: 0.85em;
    font-style: italic;
    display: flex;
    align-items: center;
    gap: 5px;
    white-space: nowrap;
}

.certificate-issuer {
    color: var(--color-ink-soft);
    font-size: 0.9em;
    margin-bottom: 12px;
}

.certificate-description {
    margin-bottom: 15px;
    line-height: 1.6;
}

.certificate-links {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 15px;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--color-border);
}

.certificate-link {
    display: inline-flex;
    align-items: center;
    background-color: var(--color-primary);
    color: white;
    padding: 6px 14px;
    border-radius: 4px;
    text-decoration: none;
    font-size: 0.9em;
    transition: all 0.3s ease;
    gap: 5px;
}

.certificate-link:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
}

.description-toggle {
    background: none;
    border: none;
    color: var(--color-primary);
    cursor: pointer;
    padding: 6px 0;
    font-size: 0.9em;
    display: flex;
    align-items: center;
    gap: 5px;
}

.description-toggle:hover {
    text-decoration: underline;
}

.description-content {
    height: 0;
    overflow: hidden;
    transition: all 0.3s ease;
    opacity: 0;
}

.description-content.show {
    height: auto;
    opacity: 1;
    margin-top: 15px;
}

.description-inner {
    background-color: var(--color-primary-tint);
    padding: 15px;
    border-radius: 6px;
    border-left: 3px solid var(--color-primary);
}

.description-inner h5 {
    margin-bottom: 10px;
    font-size: 0.95em;
}

.description-inner ul {
    padding-left: 20px;
    margin-bottom: 0;
    column-gap: 28px;
}

.description-inner li {
    margin-bottom: 6px;
    font-size: 0.9em;
    break-inside: avoid;
}

@media (min-width: 700px) {
    .description-inner ul {
        column-count: 2;
    }
}

@media (max-width: 768px) {
    .certificate-header {
        flex-direction: column;
    }
    .certificate-links {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    .certificate-link, .description-toggle {
        width: 100%;
        justify-content: center;
    }
}