/* ============================================================
   CSS Custom Properties
   ============================================================ */
:root {
  --accent:         #1e3a5f;
  --accent-hover:   #2d5a9e;
  --bg:             #ffffff;
  --bg-secondary:   #f6f8fa;
  --text:           #1a1a2e;
  --text-muted:     #6b7280;
  --border:         #e5e7eb;
  --card-bg:        #ffffff;
  --shadow:         0 1px 4px rgba(0, 0, 0, 0.08);
  --nav-height:     60px;
  --sidebar-width:  260px;
  --content-max:    1100px;
}

[data-theme="dark"] {
  --accent:         #5b8fd1;
  --accent-hover:   #7aabf5;
  --bg:             #0d1117;
  --bg-secondary:   #161b22;
  --text:           #e6edf3;
  --text-muted:     #8b949e;
  --border:         #30363d;
  --card-bg:        #161b22;
  --shadow:         0 1px 4px rgba(0, 0, 0, 0.4);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 20px);
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-size: 15px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
  transition: background 0.2s ease, color 0.2s ease;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s;
}

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

ul {
  list-style: none;
}

h2 {
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--text);
  border-bottom: 2px solid var(--accent);
  padding-bottom: 0.45rem;
  margin-bottom: 1.25rem;
}

h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

/* ============================================================
   Top Navigation
   ============================================================ */
.topnav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: background 0.2s ease;
}

.nav-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 0.5rem;
}

.nav-brand {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--text);
  white-space: nowrap;
  text-decoration: none;
  margin-right: 0.5rem;
}

.nav-brand:hover {
  color: var(--accent);
  text-decoration: none;
}

.nav-links {
  display: flex;
  flex: 1;
}

.nav-links a {
  padding: 0 0.8rem;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  text-decoration: none;
}

.theme-toggle {
  margin-left: auto;
  flex-shrink: 0;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  width: 34px;
  height: 34px;
  cursor: pointer;
  color: var(--text-muted);
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.15s, color 0.15s;
}

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

/* ============================================================
   Page Layout
   ============================================================ */
.page-wrapper {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
  display: flex;
  gap: 3.5rem;
  align-items: flex-start;
}

/* ============================================================
   Sidebar
   ============================================================ */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  position: sticky;
  top: calc(var(--nav-height) + 1.5rem);
  text-align: center;
}

.profile-photo-wrap {
  width: 148px;
  height: 148px;
  margin: 0 auto 1rem;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid var(--accent);
  background: var(--bg-secondary);
}

.profile-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.photo-fallback {
  width: 100%;
  height: 100%;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: 2.75rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--bg-secondary);
}

.sidebar-name {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.3rem;
}

.sidebar-role {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 0.1rem;
}

.sidebar-inst {
  font-size: 0.875rem;
  margin-bottom: 1.5rem;
}

.sidebar-inst a {
  color: var(--accent);
}

.sidebar-social {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  align-items: flex-start;
  padding-left: 2rem;
}

.social-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.875rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.15s;
}

.social-item:hover {
  color: var(--accent);
  text-decoration: none;
}

.social-item i {
  width: 16px;
  text-align: center;
  font-size: 0.9rem;
}

/* ============================================================
   Main Content
   ============================================================ */
.content {
  flex: 1;
  min-width: 0;
}

section {
  margin-bottom: 3.5rem;
}

.section-note {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: -0.75rem;
  margin-bottom: 1rem;
}

/* Research Interests */
.interests {
  margin-top: 1.25rem;
}

.interests ul {
  list-style: disc;
  padding-left: 1.5rem;
}

.interests li {
  margin-bottom: 0.2rem;
  font-size: 0.9rem;
}

/* ============================================================
   News
   ============================================================ */
.news-list {
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
}

.news-list li {
  display: flex;
  gap: 1rem;
  align-items: baseline;
}

.news-date {
  flex-shrink: 0;
  min-width: 72px;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.01em;
}

.news-text {
  font-size: 0.9rem;
  color: var(--text);
}

/* ============================================================
   Publications
   ============================================================ */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.pub-item {
  display: flex;
  gap: 1.25rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.1rem 1.25rem;
  transition: box-shadow 0.15s, border-color 0.15s;
}

.pub-item:hover {
  box-shadow: 0 3px 14px rgba(30, 58, 95, 0.12);
  border-color: var(--accent);
}

[data-theme="dark"] .pub-item:hover {
  box-shadow: 0 3px 14px rgba(0, 0, 0, 0.4);
}

.pub-thumb {
  flex-shrink: 0;
  width: 84px;
  height: 110px;
  border-radius: 6px;
  overflow: hidden;
  background: var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
}

.pub-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.pub-thumb-placeholder {
  color: var(--text-muted);
  font-size: 1.6rem;
}

.pub-info {
  flex: 1;
  min-width: 0;
}

.pub-title {
  font-weight: 600;
  font-size: 0.9rem;
  line-height: 1.4;
  margin-bottom: 0.3rem;
}

.pub-authors {
  font-size: 0.83rem;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}

.pub-venue {
  font-size: 0.83rem;
  color: var(--accent);
  font-style: italic;
  margin-bottom: 0.55rem;
}

.pub-links {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
}

.pub-link {
  font-size: 0.76rem;
  font-weight: 500;
  padding: 0.15rem 0.55rem;
  border: 1px solid var(--accent);
  border-radius: 4px;
  color: var(--accent);
  text-decoration: none;
  transition: background 0.15s, color 0.15s;
}

.pub-link:hover {
  background: var(--accent);
  color: #ffffff;
  text-decoration: none;
}

/* ============================================================
   Timeline  (Experience & Education)
   ============================================================ */
.timeline {
  padding-left: 1rem;
  border-left: 2px solid var(--border);
  display: flex;
  flex-direction: column;
}

.timeline-item {
  position: relative;
  padding: 0 0 1.75rem 1.5rem;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -6px;
  top: 7px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
}

.timeline-date {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 0.2rem;
  letter-spacing: 0.01em;
}

.timeline-role {
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.1rem;
}

.timeline-org {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
}

.timeline-desc {
  font-size: 0.85rem;
  color: var(--text);
}

/* ============================================================
   Talks
   ============================================================ */
.talks-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.talk-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
}

.talk-item:first-child {
  padding-top: 0;
}

.talk-item:last-child {
  border-bottom: none;
}

.talk-title {
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.2rem;
}

.talk-event {
  font-size: 0.83rem;
  color: var(--text-muted);
  margin-bottom: 0.45rem;
}

.talk-links {
  display: flex;
  gap: 0.45rem;
}

/* ============================================================
   Footer
   ============================================================ */
footer {
  text-align: center;
  padding: 2rem 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 800px) {
  .page-wrapper {
    flex-direction: column;
    padding: 1.5rem 1rem 3rem;
    gap: 2rem;
  }

  .sidebar {
    width: 100%;
    position: static;
    text-align: center;
  }

  .sidebar-social {
    align-items: center;
    padding-left: 0;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.75rem 1.25rem;
  }

  .nav-links {
    display: none;
  }

  .nav-brand {
    flex: 1;
  }
}

@media (max-width: 500px) {
  .pub-item {
    flex-direction: column;
  }

  .pub-thumb {
    width: 100%;
    height: 100px;
  }
}