/* ── Academic theme ── */
@import url('https://fonts.googleapis.com/css2?family=Lora:wght@400;600;700&family=Inter:wght@300;400;500;600&display=swap');

:root {
    --primary:       #1e3a5f;
    --primary-light: #2c5282;
    --background:    #f7f8fb;
    --foreground:    #1a202c;
    --light:         #ffffff;
    --muted:         #4a5568;
    --border:        #cbd5e0;
    --tag-bg:        #eef2f7;
}

body {
    margin: 0;
    padding: 0;
    font-family: 'Inter', Arial, sans-serif;
    font-size: 15px;
    line-height: 1.75;
    background-color: var(--background);
    color: var(--foreground);
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* ── Dark theme ── */
body.dark {
    --primary:       #4a7fc1;
    --primary-light: #63a0d4;
    --background:    #0f1923;
    --foreground:    #e8eaf0;
    --light:         #1a2638;
    --muted:         #a0aec0;
    --border:        #2d3748;
    --tag-bg:        #1e2d42;
}

/* ── Fixed header ── */
.header {
    background-color: var(--light);
    padding: 0 24px;
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 1000;
    border-bottom: 3px solid var(--primary);
    box-shadow: 0 1px 6px rgba(0, 0, 0, 0.07);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 54px;
    box-sizing: border-box;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 1rem;
    padding: 3px 9px;
    cursor: pointer;
    color: var(--muted);
    transition: border-color 0.2s, color 0.2s;
    flex-shrink: 0;
}
.theme-toggle:hover {
    border-color: var(--primary);
    color: var(--primary);
}

/* ── Navigation ── */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    max-width: 1050px;
    margin: 0 auto;
    height: 54px;
}

.nav-left,
.nav-right {
    display: flex;
    align-items: center;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    align-items: center;
    gap: 2px;
}

nav ul li a {
    text-decoration: none;
    color: var(--muted);
    font-size: 0.875rem;
    font-weight: 500;
    padding: 5px 9px;
    border-radius: 3px;
    transition: color 0.2s, background-color 0.2s;
}
nav ul li a:hover {
    color: var(--primary);
    background-color: var(--tag-bg);
    text-decoration: none;
}

nav ul li.brand a {
    font-family: 'Lora', Georgia, serif;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--primary);
    padding: 0 14px 0 0;
    margin-right: 4px;
    border-right: 1px solid var(--border);
}
nav ul li.brand a:hover {
    background: none;
    color: var(--primary-light);
}

@media (max-width: 768px) {
    .navbar    { flex-wrap: wrap; height: auto; }
    .nav-right ul { flex-wrap: wrap; }
    .header    { height: auto; padding: 6px 16px; }
    .container { padding-top: 100px; }
}

/* ── Main container ── */
.container {
    max-width: 920px;
    margin: 0 auto;
    padding: 84px 24px 60px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

main {
    background: transparent;
    padding: 0;
    width: 100%;
}

/* ── Section cards ── */
section {
    background: var(--light);
    border: 1px solid var(--border);
    border-left: 4px solid var(--primary);
    padding: 28px 32px;
    margin-bottom: 26px;
    width: 100%;
    box-sizing: border-box;
    transition: box-shadow 0.2s;
}
section:hover {
    box-shadow: 0 2px 14px rgba(0, 0, 0, 0.07);
}

html { scroll-behavior: smooth; }

/* ── Typography ── */
h2 {
    font-family: 'Lora', Georgia, serif;
    color: var(--foreground);
    font-size: 1.18rem;
    font-weight: 700;
    margin: 0 0 18px 0;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border);
    letter-spacing: 0.01em;
}

h3 {
    color: var(--foreground);
    font-size: 0.97rem;
    font-weight: 600;
    margin: 0 0 3px 0;
}

p {
    color: var(--muted);
    margin: 6px 0;
    line-height: 1.75;
}

a {
    text-decoration: none;
    color: var(--primary-light);
    transition: color 0.2s;
}
a:hover {
    color: var(--primary);
    text-decoration: underline;
}

.about-link {
    color: var(--primary-light);
    font-weight: 500;
}
.about-link:hover { text-decoration: underline; }

/* ── About section ── */
.about-content {
    display: flex;
    align-items: flex-start;
    gap: 32px;
    flex-wrap: wrap;
}

.about-image {
    flex: 0 0 140px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.profile-img {
    width: 140px;
    height: 140px;
    object-fit: cover;
    border-radius: 4px;
    border: 2px solid var(--border);
    display: block;
}

.profile-links {
    display: flex;
    flex-direction: column;
    gap: 0;
    width: 100%;
}
.profile-links a {
    font-size: 0.81rem;
    color: var(--muted);
    text-decoration: none;
    padding: 5px 0;
    border-bottom: 1px solid var(--border);
    display: block;
    font-weight: 400;
}
.profile-links a:last-child { border-bottom: none; }
.profile-links a:hover {
    color: var(--primary);
    text-decoration: none;
}

.about-text {
    flex: 1;
    min-width: 220px;
}
.about-text p {
    padding: 0;
    margin: 9px 0;
}

@media (max-width: 580px) {
    .about-content { flex-direction: column; align-items: center; }
    .about-image   { width: 100%; align-items: center; }
}

/* ── Research interest tags ── */
.interests-label {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--foreground);
    text-transform: uppercase;
    letter-spacing: 0.07em;
    margin: 16px 0 8px;
}

.interests-list {
    display: flex;
    flex-wrap: wrap;
    gap: 7px;
    margin: 0;
    padding: 0;
    list-style: none;
}
.interests-list li {
    background: var(--tag-bg);
    border: 1px solid var(--border);
    border-radius: 3px;
    padding: 3px 10px;
    font-size: 0.81rem;
    color: var(--primary);
    font-weight: 500;
}

/* ── News section ── */
.news-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.news-list li {
    display: flex;
    gap: 20px;
    padding: 9px 0;
    border-bottom: 1px solid var(--border);
    align-items: baseline;
}
.news-list li:last-child { border-bottom: none; }

.news-date {
    flex: 0 0 96px;
    font-size: 0.79rem;
    color: var(--primary);
    font-weight: 600;
    white-space: nowrap;
}
.news-content {
    color: var(--muted);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* ── Publications ── */
.pub-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.pub-list li {
    padding: 13px 0;
    border-bottom: 1px solid var(--border);
    font-size: 0.9rem;
    color: var(--muted);
    line-height: 1.65;
    display: flex;
    gap: 14px;
}
.pub-list li:last-child { border-bottom: none; padding-bottom: 0; }

.pub-num {
    flex: 0 0 18px;
    color: var(--primary);
    font-weight: 700;
    font-size: 0.82rem;
    padding-top: 2px;
}
.pub-body { flex: 1; }

.pub-badge {
    display: inline-block;
    font-size: 0.7rem;
    padding: 1px 6px;
    border-radius: 3px;
    margin-left: 7px;
    vertical-align: middle;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.pub-badge.paper  { background: #e6f0ff; color: #1e40af; border: 1px solid #bfdbfe; }
.pub-badge.poster { background: #f0fdf4; color: #166534; border: 1px solid #bbf7d0; }

/* ── Skills grid ── */
.skills-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px 40px;
}
@media (max-width: 580px) { .skills-grid { grid-template-columns: 1fr; } }

.skills-category h3 {
    font-size: 0.76rem;
    text-transform: uppercase;
    letter-spacing: 0.09em;
    color: var(--primary);
    margin: 0 0 7px 0;
    padding-bottom: 5px;
    border-bottom: 1px solid var(--border);
    font-weight: 700;
}
.skills-category p {
    font-size: 0.88rem;
    margin: 0;
    padding: 0;
    color: var(--muted);
}

/* ── Experience / Research items ── */
.experience-item {
    margin-bottom: 22px;
    padding-bottom: 22px;
    border-bottom: 1px solid var(--border);
}
.experience-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.exp-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 2px;
}
.exp-title    { font-weight: 600; color: var(--foreground); font-size: 0.97rem; }
.exp-duration { font-size: 0.81rem; color: var(--primary); font-weight: 600; white-space: nowrap; }
.exp-meta     { font-size: 0.86rem; color: var(--muted); font-style: italic; margin: 2px 0 8px 0; }

.exp-current {
    display: inline-block;
    background: var(--tag-bg);
    border: 1px solid var(--border);
    color: var(--primary);
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 1px 7px;
    border-radius: 3px;
    vertical-align: middle;
    margin-left: 7px;
}

.experience-item ul {
    margin: 6px 0 0 0;
    padding-left: 18px;
    list-style: disc;
}
.experience-item ul li {
    color: var(--muted);
    font-size: 0.9rem;
    margin-bottom: 4px;
    line-height: 1.65;
}

/* ── Project items ── */
.project-item {
    margin-bottom: 22px;
    padding-bottom: 22px;
    border-bottom: 1px solid var(--border);
}
.project-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}
.project-item h3  { margin-bottom: 2px; }
.project-item ul {
    margin: 6px 0 0 0;
    padding-left: 18px;
    list-style: disc;
}
.project-item ul li {
    color: var(--muted);
    font-size: 0.9rem;
    margin-bottom: 4px;
    line-height: 1.65;
}

/* ── Contact ── */
.contact-row {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-top: 6px;
}
.contact-row a {
    font-size: 0.9rem;
    color: var(--muted);
    text-decoration: none;
    border-bottom: 1px solid var(--border);
    padding-bottom: 2px;
}
.contact-row a:hover {
    color: var(--primary);
    border-color: var(--primary);
    text-decoration: none;
}

/* ── Misc ── */
ul { line-height: 1.9; }