/* Gradfolio Dark Theme */
:root {
  --bg-color: #0d1117;
  --bg-secondary: #161b22;
  --text-color: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  --accent-hover: #79c0ff;
  --border-color: #30363d;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  font-size: 16px;
}

a {
  color: var(--accent-color);
  text-decoration: none;
  transition: color 0.2s;
}

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

/* Header */
header {
  padding: 2rem 0;
  border-bottom: 1px solid var(--border-color);
}

.header-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-color);
}

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

nav a {
  color: var(--text-secondary);
  font-weight: 500;
}

nav a:hover,
nav a.active {
  color: var(--accent-color);
}

/* Main Content */
main {
  max-width: 900px;
  margin: 0 auto;
  padding: 4rem 2rem;
  min-height: calc(100vh - 200px);
}

/* Hero Section */
.hero {
  margin-bottom: 4rem;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.hero-description {
  font-size: 1.1rem;
  line-height: 1.8;
  color: var(--text-secondary);
  max-width: 700px;
}

/* Section Headings */
h2 {
  font-size: 2rem;
  margin-bottom: 2rem;
  color: var(--text-color);
}

h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text-color);
}

/* About Section */
.about-content p {
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* Projects Grid */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.project-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
  transition: transform 0.2s, border-color 0.2s;
}

.project-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-color);
}

.project-card h3 {
  margin-bottom: 0.75rem;
  font-size: 1.25rem;
}

.project-card p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}

.tag {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

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

/* Publications */
.publication-item {
  margin-bottom: 2rem;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border-left: 3px solid var(--accent-color);
  border-radius: 4px;
}

.publication-item p {
  color: var(--text-secondary);
  line-height: 1.8;
}

.pdf-link {
  color: var(--accent-color);
  font-weight: 600;
  margin-left: 0.5rem;
}

/* Book Section */
.book-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 2rem;
  margin-top: 2rem;
}

.book-section h3 {
  color: var(--accent-color);
}

.book-section p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.8;
}

.book-topics {
  list-style: none;
  margin-top: 1rem;
}

.book-topics li {
  padding: 0.5rem 0;
  padding-left: 1.5rem;
  color: var(--text-secondary);
  position: relative;
}

.book-topics li:before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent-color);
}

/* Contact Section */
.contact-info {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: 2rem;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--text-secondary);
}

.social-links {
  display: flex;
  gap: 1.5rem;
  margin-top: 2rem;
}

.social-links a {
  font-size: 1.1rem;
  padding: 0.5rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  transition: all 0.2s;
}

.social-links a:hover {
  border-color: var(--accent-color);
  background: var(--bg-color);
}

/* Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  text-align: center;
  color: var(--text-secondary);
}

.footer-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Responsive */
@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 1rem;
  }

  nav ul {
    gap: 1rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

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

  main {
    padding: 2rem 1rem;
  }
}