/* Reset and base styling */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", Tahoma, sans-serif;
  line-height: 1.6;
  background: #fafafa;
  color: #222;
}

/* --- Navigation --- */
header {
  position: sticky;
  top: 0;
  background: #ffffff;
  border-bottom: 1px solid #ddd;
  z-index: 1000;
}

.nav-container {
  max-width: 900px;
  margin: auto;
  padding: 0.5rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
  text-decoration: none;
  color: #333;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.2rem;
}

.nav-links a {
  text-decoration: none;
  color: #555;
  transition: color 0.3s;
}

.nav-links a:hover,
.nav-links a.active {
  color: #007acc;
}

/* Mobile toggle */
.mobile-menu-toggle {
  display: none;
  font-size: 1.5rem;
  background: none;
  border: none;
}

@media (max-width: 768px) {
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    background: #fff;
    display: none;
    border-top: 1px solid #ddd;
  }
  .nav-links.show {
    display: flex;
  }
  .mobile-menu-toggle {
    display: block;
  }
}

/* --- Hero Section --- */
.section-hero {
  background: linear-gradient(to right, #0c1a2c, #1b2f47);
  color: #fff;
  padding: 4rem 1rem;
  text-align: center;
}

.hero-flex {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
  max-width: 900px;
  margin: auto;
}

.profile-pic img {
  width: 220px;
  height: 220px;
  object-fit: cover;
  border-radius: 50%;
  border: 3px solid #38bdf8;
  box-shadow: 0 4px 12px rgba(0,0,0,0.3);
}

.hero-text h1 {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.hero-text p {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.quick-highlights {
  font-size: 0.95rem;
  margin-bottom: 1rem;
  color: #cbd5e1;
}

.btn-primary {
  display: inline-block;
  margin-top: 1rem;
  padding: 0.8rem 1.5rem;
  background: #38bdf8;
  color: #111;
  border: none;
  border-radius: 6px;
  text-decoration: none;
  font-weight: bold;
  transition: background 0.3s;
}

.btn-primary:hover {
  background: #0ea5e9;
}

/* --- Sections --- */
.section-light {
  background: #fff;
  padding: 3rem 1rem;
}

.section-dark {
  background: #f0f4f8;
  padding: 3rem 1rem;
}

.section-highlight {
  background: #e0f2fe;
  padding: 3rem 1rem;
}

.section-inner {
  max-width: 900px;
  margin: auto;
}

.section-inner h2 {
  margin-bottom: 1.5rem;
  font-size: 2rem;
  color: #333;
}

/* --- Featured Publication --- */
.featured-card {
  display: flex;
  align-items: flex-start;
  gap: 1.5rem;
  flex-wrap: wrap;
  background: #fff;
  border-radius: 10px;
  padding: 1.5rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.featured-card img {
  width: 500px;
  max-width: 100%;
  border-radius: 6px;
  border: 2px solid #ddd;
}

.featured-text h3 {
  color: #007acc;
  margin-bottom: 0.5rem;
}

.featured-text p {
  margin-bottom: 0.8rem;
}

/* --- Publications --- */
.pub-item {
  margin-bottom: 2rem;
}

.pub-item img {
  width: 300px;
  max-width: 100%;
  border-radius: 6px;
  border: 2px solid #ddd;
}

.pub-item h3 {
  font-size: 1.25rem;
  color: #007acc;
  margin-bottom: 0.5rem;
}

/* --- Badge Grid --- */
.badge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1.2rem;
  justify-items: center;
}

.badge-grid img {
  width: 220px;
  height: auto;
  border-radius: 8px;
  border: 1px solid #ddd;
  background: #fff;
  padding: 0.5rem;
  transition: transform 0.3s, box-shadow 0.3s;
}

.badge-grid img:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

/* --- Back to top --- */
#back-to-top {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  background: #007acc;
  color: #fff;
  border: none;
  padding: 0.6rem 0.9rem;
  border-radius: 50%;
  font-size: 1.25rem;
  display: none;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
  transition: background 0.3s;
}

#back-to-top:hover {
  background: #005fa3;
}

/* --- Footer --- */
footer {
  background: #333;
  color: #eee;
  text-align: center;
  padding: 1.5rem 1rem;
  margin-top: 2rem;
}

.footer-inner p {
  margin: 0;
}