/* Professional PhD Student Website */

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary-color: #1a3a52;
  --secondary-color: #2c5aa0;
  --accent-color: #d4a574;
  --text-dark: #2c3e50;
  --text-light: #ecf0f1;
  --border-color: #bdc3c7;
  --bg-light: #f8f9fa;
  --font-serif: 'Georgia', 'Times New Roman', serif;
  --font-sans: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  font-family: var(--font-sans);
  color: var(--text-dark);
  line-height: 1.6;
  background-color: #ffffff;
}

/* Header & Navigation */
header {
  background-color: var(--primary-color);
  color: var(--text-light);
  padding: 2rem 0;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

header h1 {
  font-size: 1.8rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  letter-spacing: 0.5px;
}

header p {
  font-size: 0.95rem;
  opacity: 0.9;
  font-style: italic;
}

nav {
  background-color: var(--secondary-color);
  padding: 1rem 0;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 0;
}

nav li {
  flex: 1;
  text-align: center;
}

nav a {
  display: block;
  color: var(--text-light);
  text-decoration: none;
  padding: 0.75rem 1rem;
  transition: background-color 0.3s ease;
  font-weight: 500;
}

nav a:hover {
  background-color: var(--accent-color);
  color: var(--primary-color);
}

/* Main Content */
main {
  max-width: 1000px;
  margin: 0 auto;
  padding: 2rem;
}

section {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-color);
}

section:last-child {
  border-bottom: none;
}

h2 {
  font-size: 1.6rem;
  color: var(--primary-color);
  margin-bottom: 1.5rem;
  font-weight: 600;
  border-left: 4px solid var(--accent-color);
  padding-left: 1rem;
}

h3 {
  font-size: 1.2rem;
  color: var(--secondary-color);
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
  font-weight: 600;
}

p {
  margin-bottom: 1rem;
  text-align: justify;
}

/* Links */
a {
  color: var(--secondary-color);
  text-decoration: none;
  transition: color 0.3s ease;
  font-weight: 500;
}

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

/* Lists */
ul, ol {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

li {
  margin-bottom: 0.5rem;
}

/* Research & Publications */
.research-item, .publication-item, .education-item {
  background-color: var(--bg-light);
  padding: 1.25rem;
  margin-bottom: 1.25rem;
  border-left: 3px solid var(--accent-color);
  border-radius: 2px;
}

.research-item h4, .publication-item h4, .education-item h4 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
}

.research-item p, .publication-item p, .education-item p {
  font-size: 0.95rem;
  margin-bottom: 0.5rem;
}

.publication-meta {
  font-size: 0.9rem;
  color: #7f8c8d;
  font-style: italic;
}

/* Contact & Social */
.contact-section {
  background-color: var(--bg-light);
  padding: 2rem;
  border-radius: 4px;
  margin-top: 2rem;
}

.contact-section h3 {
  margin-top: 0;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.social-links {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background-color: var(--primary-color);
  color: var(--text-light);
  border-radius: 50%;
  transition: background-color 0.3s ease, transform 0.3s ease;
}

.social-links a:hover {
  background-color: var(--accent-color);
  color: var(--primary-color);
  transform: translateY(-3px);
  text-decoration: none;
}

/* Footer */
footer {
  background-color: var(--primary-color);
  color: var(--text-light);
  text-align: center;
  padding: 2rem;
  margin-top: 3rem;
  font-size: 0.9rem;
}

footer a {
  color: var(--accent-color);
}

footer a:hover {
  color: var(--text-light);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--secondary-color);
  color: var(--text-light);
  text-decoration: none;
  border-radius: 4px;
  transition: background-color 0.3s ease, transform 0.2s ease;
  border: none;
  cursor: pointer;
  font-weight: 600;
}

.btn:hover {
  background-color: var(--accent-color);
  color: var(--primary-color);
  transform: translateY(-2px);
}

/* Responsive Design */
@media (max-width: 768px) {
  header h1 {
    font-size: 1.5rem;
  }

  nav ul {
    flex-direction: column;
  }

  nav li {
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  }

  main {
    padding: 1.5rem;
  }

  h2 {
    font-size: 1.4rem;
  }

  h3 {
    font-size: 1.1rem;
  }

  .contact-section {
    padding: 1.5rem;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 14px;
  }

  header h1 {
    font-size: 1.3rem;
  }

  nav a {
    padding: 0.6rem 0.5rem;
    font-size: 0.9rem;
  }

  main {
    padding: 1rem;
  }

  h2 {
    font-size: 1.2rem;
  }

  section {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
  }
}