/* ── Base ── */
:root {
  --theme: #00356b;
  --dark: #222;
  --gray: #555;
  --light-gray: #f7f7f7;
  --white: #fff;
  --max-width: 960px;
  --font-body: 'Source Sans Pro', 'Segoe UI', sans-serif;
  --font-heading: 'Libre Baskerville', 'Georgia', serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
section { scroll-margin-top: 100px; }
#home { scroll-margin-top: 0; margin-top: 0; padding-top: 0; }

body {
  font-family: var(--font-body);
  color: var(--dark);
  line-height: 1.7;
  font-size: 20px;
  background: var(--white);
}

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

/* ── Header / Nav ── */
header {
  background: var(--theme);
  padding: 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

nav {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
}

nav .site-name {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  color: var(--white);
  text-decoration: none;
  letter-spacing: 0.5px;
}

nav .nav-links { display: flex; gap: 28px; }

nav .nav-links a {
  color:var(--light-gray);
  font-size: 1.25rem;
  text-decoration: none;
  transition: color 0.2s;
}

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

/* ── Main Content ── */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 20px 80px;
}

/* ── Home page ── */
.home-intro {
  display: flex;
  gap: 48px;
  align-items: flex-start;
  justify-content: center;
  margin-bottom: 32px;
}

.home-intro .photo {
  width: 360px;
  min-width: 360px;
  border-radius: 6px;
  margin-top: 65px;
}

.home-intro .links a,
.home-intro .links button {
  font-size: 1rem;
  padding: 6px 16px;
}

.home-intro .bio h1 {
  font-family: var(--font-heading);
  font-size: 1.8rem;
  margin-bottom: 4px;
  color: var(--theme);
}

.home-intro .bio .subtitle {
  color: var(--gray);
  font-size: 1.25rem;
  margin-bottom: 16px;
}

.home-intro .bio p {
  margin-bottom: 12px;
}

.info-line {
  color: var(--gray);
  font-size: 1rem;
}

.info-line a { color: var(--theme); }

/* ── Section headings ── */
h2 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  color: var(--theme);
  margin: 40px 0 18px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--theme);
}

h3 {
  font-size: 1rem;
  margin: 24px 0 8px;
  color: var(--dark);
}

/* ── Research page ── */
.paper {
  margin-bottom: 22px;
  scroll-margin-top: 100px;
}

.paper .title {
  font-weight: 600;
}

.paper .title a {
  color: var(--theme);
}

.paper .authors,
.paper .venue,
.paper .note {
  font-size: 1rem;
  color: var(--gray);
}

.paper .authors a {
  color: var(--gray);
}

.paper .venue {
  font-weight: bold;
}

.paper .note {
  font-size: 1rem;
  color: var(--gray);
}

.links {
  margin-top: 6px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.links a,
.links button {
  display: inline-block;
  font-family: var(--font-body);
  font-size: 0.85rem;
  line-height: 1.4;
  padding: 3px 12px;
  border: 1px solid var(--theme);
  border-radius: 3px;
  color: var(--theme);
  background: var(--white);
  text-decoration: none;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.links a:hover,
.links button:hover {
  background: var(--theme);
  color: var(--white);
  text-decoration: none;
}

.paper .abstract {
  display: none;
  margin-top: 10px;
  padding: 14px 16px;
  background: var(--light-gray);
  border-left: 3px solid var(--theme);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--dark);
}

.paper .abstract.open {
  display: block;
}

.paper .abstract .abstract-img {
  display: block;
  max-width: 100%;
  margin-top: 12px;
}

/* ── Contact page ── */
.contact-info {
  line-height: 2;
}

.contact-info dt {
  font-weight: 600;
  color: var(--theme);
  display: inline;
}

.contact-info dd {
  display: inline;
  margin: 0;
}

.contact-info dd::after {
  content: '';
  display: block;
}

/* ── Footer ── */
footer {
  text-align: center;
  padding: 24px 20px;
  color: var(--gray);
  font-size: 0.85rem;
  border-top: none;
}

/* ── Responsive ── */
@media (max-width: 600px) {
  .home-intro {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  main { padding-top: 20px; }
  .home-intro .photo { width: 200px; min-width: auto; }
  .home-intro .links { justify-content: center; }
  nav { flex-direction: column; gap: 8px; }
  nav .site-name { font-size: 1.2rem; }
  nav .nav-links { gap: 16px; }
  nav .nav-links a { font-size: 1rem; }
  section { scroll-margin-top: 110px; }
  #home { scroll-margin-top: 0; }
}