:root {
  --background: #ffffff;
  --surface: #f7f9fb;
  --surface-2: #eef3f8;
  --text: #1f2937;
  --muted: #64748b;
  --border: #dbe3ec;
  --accent: #0b5ea8;
  --accent-dark: #084b87;
  --header-height: 68px;
  --content-width: 1200px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.72;
}

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

a:hover { text-decoration: underline; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: rgba(255,255,255,.97);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
}

.header-inner {
  max-width: var(--content-width);
  height: 100%;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-brand {
  color: var(--text);
  font-size: 1.03rem;
  font-weight: 750;
  letter-spacing: -.01em;
}

.site-brand:hover { text-decoration: none; }

.top-nav {
  display: flex;
  align-items: center;
  gap: 23px;
}

.top-nav a {
  color: var(--muted);
  font-weight: 620;
  font-size: .92rem;
}

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

.menu-button {
  display: none;
  background: transparent;
  border: 0;
  font-size: 1.55rem;
  cursor: pointer;
}

.page-shell {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 48px 24px 80px;
  display: grid;
  grid-template-columns: 265px minmax(0, 1fr);
  gap: 70px;
}

.profile-card {
  position: sticky;
  top: calc(var(--header-height) + 32px);
}

.profile-image,
.avatar-fallback {
  width: 185px;
  height: 185px;
  border-radius: 50%;
}

.profile-image {
  display: block;
  object-fit: cover;
  border: 1px solid var(--border);
}

.avatar-fallback {
  display: none;
  align-items: center;
  justify-content: center;
  background: linear-gradient(145deg, var(--surface-2), var(--surface));
  border: 1px solid var(--border);
  color: var(--accent);
  font-size: 3rem;
  font-weight: 800;
}

.profile-card h1 {
  margin: 21px 0 3px;
  font-size: 1.55rem;
  line-height: 1.25;
}

.role {
  margin: 0 0 5px;
  font-weight: 650;
}

.bio {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: .93rem;
}

.profile-links {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  font-size: .94rem;
}

.profile-item { color: var(--muted); }

.main-content {
  min-width: 0;
  max-width: 850px;
}

.main-content > h1:first-child { margin-top: 0; }

h1, h2, h3 { line-height: 1.3; }

h1 {
  margin-bottom: 20px;
  font-size: clamp(2rem, 5vw, 2.8rem);
  letter-spacing: -.025em;
}

h2 {
  margin-top: 46px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  font-size: 1.5rem;
}

h3 {
  margin-top: 24px;
  font-size: 1.1rem;
}

p { margin: 0 0 18px; }

ul, ol { padding-left: 23px; }

li { margin: 5px 0; }

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 28px 0 36px;
}

.button {
  display: inline-block;
  padding: 10px 17px;
  border: 1px solid var(--border);
  border-radius: 7px;
  background: var(--background);
  color: var(--text);
  font-weight: 650;
  line-height: 1.25;
}

.button:hover {
  background: var(--surface);
  text-decoration: none;
}

.button-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.button-primary:hover {
  background: var(--accent-dark);
  color: #fff;
}

.stats-grid,
.skills-grid,
.project-grid {
  display: grid;
  gap: 14px;
  margin: 24px 0;
}

.stats-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.skills-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.project-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }

.stat-card,
.skill-card,
.project-card,
.timeline-item,
.education-card,
.publication-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--background);
}

.stat-card {
  padding: 16px;
  text-align: center;
}

.stat-card strong {
  display: block;
  color: var(--accent);
  font-size: 1.05rem;
}

.stat-card span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: .8rem;
}

.skill-card { padding: 18px; }

.skill-card h3 {
  margin: 0 0 8px;
  font-size: 1rem;
}

.skill-card p {
  margin: 0;
  color: var(--muted);
}

.project-card {
  padding: 19px 20px;
}

.project-card h3 {
  margin: 0 0 9px;
  color: var(--text);
}

.project-card p {
  margin-bottom: 13px;
  color: var(--muted);
}

.tag {
  display: inline-block;
  margin: 3px 4px 0 0;
  padding: 3px 8px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--accent-dark);
  font-size: .77rem;
  font-weight: 650;
}

.timeline {
  border-left: 2px solid var(--border);
  padding-left: 25px;
}

.timeline-item {
  position: relative;
  margin: 25px 0;
  padding: 7px 23px 20px;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 29px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--accent);
}

.timeline-item h2 {
  margin-top: 17px;
  padding: 0;
  border: 0;
  font-size: 1.35rem;
}

.education-card,
.publication-card {
  margin: 24px 0;
  padding: 8px 23px 20px;
}

.education-card h2,
.publication-card h2 {
  border: 0;
  padding: 0;
  margin-top: 18px;
}

.chip-list {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  margin: 16px 0 25px;
}

.chip-list span {
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 7px;
  background: var(--surface);
  font-size: .9rem;
}

.cert-list h3 { margin-bottom: 4px; }

.cv-download { margin: 24px 0 35px; }

code {
  display: inline-block;
  margin: 2px;
  padding: 3px 7px;
  border-radius: 5px;
  background: var(--surface-2);
  color: var(--accent-dark);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: .85rem;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 27px 24px;
  text-align: center;
  color: var(--muted);
  font-size: .87rem;
}

.site-footer p { margin: 0; }

@media (max-width: 950px) {
  .stats-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 820px) {
  .menu-button { display: block; }

  .top-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    padding: 14px 24px 20px;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
    background: #fff;
    border-bottom: 1px solid var(--border);
  }

  .top-nav.open { display: flex; }

  .page-shell {
    grid-template-columns: 1fr;
    gap: 34px;
    padding-top: 32px;
  }

  .profile-card {
    position: static;
    display: grid;
    grid-template-columns: 110px minmax(0, 1fr);
    column-gap: 20px;
  }

  .profile-image,
  .avatar-fallback {
    width: 110px;
    height: 110px;
    grid-row: 1 / span 4;
  }

  .profile-card h1 { margin: 2px 0 2px; }

  .profile-links {
    grid-column: 1 / -1;
    margin-top: 12px;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 8px 18px;
  }
}

@media (max-width: 600px) {
  .header-inner,
  .page-shell {
    padding-left: 18px;
    padding-right: 18px;
  }

  .profile-card { display: block; }

  .profile-image,
  .avatar-fallback {
    width: 120px;
    height: 120px;
  }

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

  h1 { font-size: 2rem; }
}