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

:root {
  --color-bg:       #ffffff;
  --color-bg-alt:   #f7f7f5;
  --color-text:     #1a1a1a;
  --color-muted:    #6b7280;
  --color-accent:   #1d4ed8;
  --color-accent-h: #1e40af;
  --color-border:   #e5e7eb;
  --color-tag-bg:   #eff6ff;
  --color-tag-text: #1d4ed8;

  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Lora', Georgia, serif;

  --max-w: 900px;
  --nav-h: 64px;
}

[data-theme="dark"] {
  --color-bg:       #0d1117;
  --color-bg-alt:   #161b22;
  --color-text:     #e6edf3;
  --color-muted:    #8b949e;
  --color-accent:   #58a6ff;
  --color-accent-h: #79c0ff;
  --color-border:   #30363d;
  --color-tag-bg:   #1f3a5c;
  --color-tag-text: #79c0ff;
}

html { scroll-behavior: smooth; font-size: 18px; }

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

@media (prefers-reduced-motion: no-preference) {
  body,
  .site-header,
  .section--alt,
  .skill-category,
  .project-card {
    transition-property: background-color, color, border-color;
    transition-duration: 0.2s;
    transition-timing-function: ease;
  }
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }

img { display: block; max-width: 100%; }

/* ── Layout ── */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

.container--narrow { max-width: 640px; }

/* ── Navigation ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
  height: var(--nav-h);
  display: flex;
  align-items: center;
}

[data-theme="dark"] .site-header {
  background: rgba(13, 17, 23, 0.92);
}

.nav {
  width: 100%;
  max-width: calc(var(--max-w) + 3rem);
  margin-inline: auto;
  padding-inline: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.nav-brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1px;
  white-space: nowrap;
  text-decoration: none;
}
.nav-brand:hover { text-decoration: none; }
.nav-brand:hover .nav-brand-name { color: var(--color-accent); }

.nav-brand-name {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
  line-height: 1.2;
  transition: color 0.15s;
}

.nav-brand-sub {
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--color-muted);
  letter-spacing: 0.01em;
  line-height: 1.2;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-muted);
  text-decoration: none;
  transition: color 0.15s;
}
.nav-links a:hover { color: var(--color-text); }
.nav-links a.active {
  color: var(--color-accent);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 2px;
}

.nav-mobile-only,
.nav-mobile-divider { display: none; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-shrink: 0;
  margin-left: 1.5rem;
  padding-left: 1.5rem;
  border-left: 1px solid var(--color-border);
}

.nav-cv-link {
  display: flex;
  align-items: center;
  height: 30px;
  padding-inline: 0.65rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-muted);
  background: var(--color-bg-alt);
  border-radius: 6px;
  text-decoration: none;
  transition: color 0.15s, background 0.15s;
}
.nav-cv-link:hover {
  color: var(--color-text);
  background: var(--color-border);
  text-decoration: none;
}

.nav-icon-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 6px;
  background: var(--color-bg-alt);
  color: var(--color-muted);
  text-decoration: none;
  transition: color 0.15s, background 0.15s;
}
.nav-icon-link:hover {
  color: var(--color-text);
  background: var(--color-border);
  text-decoration: none;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: 1.5px solid var(--color-border);
  border-radius: 6px;
  background: none;
  cursor: pointer;
  color: var(--color-muted);
  transition: color 0.15s, border-color 0.15s;
}
.theme-toggle:hover {
  color: var(--color-text);
  border-color: var(--color-text);
}

.theme-toggle .icon-sun  { display: none; }
.theme-toggle .icon-moon { display: block; }

[data-theme="dark"] .theme-toggle .icon-sun  { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* ── Sections ── */
.section {
  padding-block: 6rem;
}

.section--alt {
  background: var(--color-bg-alt);
}

.section--hero {
  padding-top: 5rem;
  padding-bottom: 6rem;
}

.section-title {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
}

.section-intro {
  color: var(--color-muted);
  max-width: 70ch;
  margin-bottom: 3rem;
  font-size: 1rem;
  line-height: 1.7;
}

.subsection-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-top: 4rem;
  margin-bottom: 0.5rem;
  padding-top: 3rem;
  border-top: 1px solid var(--color-border);
}

/* ── Hero ── */
.hero-content {
  display: flex;
  align-items: flex-start;
  gap: 3rem;
}

.hero-text { flex: 1; }

.hero-label {
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.hero-name {
  font-family: var(--font-serif);
  font-size: clamp(2.2rem, 5vw, 3rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 0.6rem;
}

.hero-affiliation {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.55;
  margin-bottom: 1.25rem;
}

.hero-bio {
  font-size: 1.05rem;
  color: var(--color-muted);
  line-height: 1.75;
  margin-bottom: 2rem;
}

.hero-bio em { color: var(--color-text); font-style: italic; }

.hero-links { display: flex; flex-wrap: wrap; gap: 0.75rem; }

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

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.55rem 1.25rem;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
  cursor: pointer;
  text-decoration: none;
}
.btn:hover { text-decoration: none; }

.btn--primary {
  background: var(--color-accent);
  color: #fff;
  border: 1.5px solid var(--color-accent);
}
.btn--primary:hover { background: var(--color-accent-h); border-color: var(--color-accent-h); }

.btn--outline {
  background: transparent;
  color: var(--color-accent);
  border: 1.5px solid var(--color-accent);
}
.btn--outline:hover { background: var(--color-accent); color: #fff; }

.btn--ghost {
  background: transparent;
  color: var(--color-muted);
  border: 1.5px solid var(--color-border);
}
.btn--ghost:hover { color: var(--color-text); border-color: var(--color-text); }

/* ── Publications ── */
.publication-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.publication {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: 1.5rem;
  padding-block: 2rem;
  border-top: 1px solid var(--color-border);
}

.pub-meta {
  padding-top: 0.1rem;
}

.pub-year {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.03em;
}

.pub-title {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 0.35rem;
  color: var(--color-text);
}

.pub-authors {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 0.25rem;
}

.pub-venue {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 0.75rem;
}

.pub-abstract {
  font-size: 0.875rem;
  color: var(--color-muted);
  line-height: 1.6;
  margin-bottom: 0.75rem;
}

.pub-links { display: flex; gap: 0.5rem; flex-wrap: wrap; }

.tag-link {
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
  border-radius: 4px;
  padding: 0.2rem 0.55rem;
  transition: background 0.15s, color 0.15s;
  text-decoration: none;
}
.tag-link:hover { background: var(--color-accent); color: #fff; text-decoration: none; }

/* ── Hero avatar (shown until a real photo is added) ── */
.hero-avatar {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  background: var(--color-bg-alt);
  border: 2px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.04em;
  flex-shrink: 0;
  user-select: none;
}

.hero-photo-img {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--color-border);
  flex-shrink: 0;
}

/* ── Skills ── */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}

.skill-category {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 1.4rem 1.5rem;
}

.skill-cat-title {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--color-muted);
  margin-bottom: 0.85rem;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

@media (max-width: 600px) {
  .skills-grid { grid-template-columns: 1fr; }
  .hero-avatar { width: 100px; height: 100px; font-size: 1.1rem; }
}

/* ── Timeline (Experience & Education) ── */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.timeline-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 1.5rem;
  padding-block: 1.75rem;
  border-top: 1px solid var(--color-border);
  align-items: start;
}
.timeline-item:last-child { border-bottom: 1px solid var(--color-border); }

.timeline-meta { padding-top: 0.2rem; }

.timeline-date {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.03em;
}

.timeline-role {
  font-size: 1.02rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--color-text);
  margin-bottom: 0.15rem;
}
.timeline-role em { font-style: italic; color: var(--color-accent); }

.timeline-org {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 0.6rem;
}

.timeline-points {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.timeline-points li {
  position: relative;
  padding-left: 1.1rem;
  font-size: 0.92rem;
  color: var(--color-text);
  line-height: 1.6;
}
.timeline-points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--color-accent);
}

@media (max-width: 600px) {
  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
  .timeline-date { display: inline-block; margin-bottom: 0.1rem; }
}

/* ── Languages & Awards ── */
.extras-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2.5rem;
}

.lang-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
}
.lang-list li {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 0.7rem;
  border-top: 1px solid var(--color-border);
}
.lang-list li:last-child { border-bottom: 1px solid var(--color-border); }

.lang-name { font-size: 0.95rem; font-weight: 500; }
.lang-level {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-tag-text);
  background: var(--color-tag-bg);
  border-radius: 4px;
  padding: 0.15rem 0.55rem;
  white-space: nowrap;
}

.award-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}
.award-title {
  display: block;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 0.15rem;
}
.award-detail {
  display: block;
  font-size: 0.875rem;
  color: var(--color-muted);
  line-height: 1.6;
}

@media (max-width: 600px) {
  .extras-grid { grid-template-columns: 1fr; gap: 2rem; }
}

/* ── Conferences ── */
.conference-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.conference {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: 1.5rem;
  padding-block: 1.75rem;
  border-top: 1px solid var(--color-border);
  align-items: start;
}
.conference:last-child { border-bottom: 1px solid var(--color-border); }

.conf-meta { padding-top: 0.15rem; }

.conf-year {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.03em;
}

.conf-name {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 0.2rem;
  color: var(--color-text);
}

.conf-location {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 0.6rem;
}

.conf-badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  border-radius: 4px;
  padding: 0.2rem 0.55rem;
  margin-bottom: 0.5rem;
}

.conf-badge--talk {
  background: #ecfdf5;
  color: #065f46;
}

.conf-badge--poster {
  background: #eff6ff;
  color: #1e40af;
}

.conf-badge--attendee {
  background: #f9fafb;
  color: #6b7280;
  border: 1px solid var(--color-border);
}

.conf-badge--school {
  background: #fdf4ff;
  color: #6b21a8;
}

[data-theme="dark"] .conf-badge--talk     { background: #064e3b; color: #6ee7b7; }
[data-theme="dark"] .conf-badge--poster   { background: #1f3a5c; color: #93c5fd; }
[data-theme="dark"] .conf-badge--attendee { background: #1f2937; color: #9ca3af; }
[data-theme="dark"] .conf-badge--school   { background: #3b0764; color: #e9d5ff; }

.conf-title {
  font-size: 0.9rem;
  color: var(--color-muted);
  font-style: italic;
  line-height: 1.5;
  margin-top: 0.1rem;
}

.conf-title-block {
  display: table;
}

.conf-title-sub {
  font-size: 0.8rem;
  color: #9ca3af;
  font-style: italic;
  line-height: 1.5;
  margin-top: 0.15rem;
  text-align: center;
  width: 100%;
}

@media (max-width: 600px) {
  .conference {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
  .conf-year { display: inline; margin-right: 0.5rem; }
}

/* ── Projects ── */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: box-shadow 0.15s, border-color 0.15s;
}
.project-card:hover {
  border-color: #c7d2fe;
  box-shadow: 0 4px 20px rgba(29, 78, 216, 0.07);
}
[data-theme="dark"] .project-card:hover {
  border-color: #3b5bdb;
  box-shadow: 0 4px 20px rgba(88, 166, 255, 0.1);
}

.project-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
}

.project-title {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text);
}

.project-gh {
  color: var(--color-muted);
  flex-shrink: 0;
  transition: color 0.15s;
  text-decoration: none;
}
.project-gh:hover { color: var(--color-text); }

.project-desc {
  font-size: 0.9rem;
  color: var(--color-muted);
  line-height: 1.65;
  flex: 1;
}

.project-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }

.tag {
  font-size: 0.75rem;
  font-weight: 500;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: 4px;
  padding: 0.2rem 0.55rem;
}

/* ── Contact ── */
.contact-methods {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.contact-item {
  display: flex;
  align-items: baseline;
  gap: 1.5rem;
  padding-block: 1.1rem;
  border-top: 1px solid var(--color-border);
  text-decoration: none;
  color: inherit;
  transition: color 0.15s;
}
.contact-item:last-child { border-bottom: 1px solid var(--color-border); }
.contact-item:hover { color: var(--color-accent); text-decoration: none; }

.contact-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--color-muted);
  width: 72px;
  flex-shrink: 0;
}
.contact-item:hover .contact-label { color: inherit; }

.contact-value {
  font-size: 0.95rem;
  font-weight: 500;
}

/* ── Footer ── */
.site-footer {
  padding-block: 2.5rem;
  border-top: 1px solid var(--color-border);
}

.site-footer p {
  font-size: 0.85rem;
  color: var(--color-muted);
  text-align: center;
}

/* ── Fade-in animation ── */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: none;
}

/* ── Responsive ── */

/* Tablets and phones: switch to hamburger menu */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    padding: 0.5rem 0;
    z-index: 99;
  }
  .nav-links.open { display: flex; }
  .nav-links li a {
    display: block;
    padding: 0.85rem 1.5rem;
    font-size: 1rem;
    color: var(--color-text);
  }
  .nav-links li a:hover { color: var(--color-accent); }

  /* Show divider + mobile-only items (CV, GitHub, LinkedIn) */
  .nav-mobile-only { display: block; }
  .nav-mobile-divider {
    display: block;
    height: 1px;
    background: var(--color-border);
    margin: 0.4rem 1.5rem;
  }

  /* Show hamburger */
  .nav-toggle { display: flex; }
  /* Enlarge toggle touch targets */
  .nav-toggle,
  .theme-toggle { width: 40px; height: 40px; }

  /* Hide secondary action links; keep theme toggle + hamburger */
  .nav-cv-link,
  .nav-icon-link { display: none; }

  /* Remove separator between brand and remaining actions */
  .nav-actions {
    margin-left: 0;
    padding-left: 0;
    border-left: none;
    gap: 0.5rem;
  }
}

/* Small phones */
@media (max-width: 600px) {
  html { font-size: 16px; }

  .hero-content {
    flex-direction: column-reverse;
    gap: 1.5rem;
  }
  .hero-photo-img {
    width: 120px;
    height: 120px;
    align-self: center;
  }

  .section { padding-block: 3.5rem; }
  .section--hero { padding-top: 2rem; padding-bottom: 3rem; }

  .publication {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
  .pub-year { display: inline; margin-right: 0.5rem; }

  .project-grid { grid-template-columns: 1fr; }

  .contact-item { flex-wrap: wrap; gap: 0.25rem; }
  .contact-label { width: auto; }
}