:root {
  --bg-color: #ffffff;
  --text-color: #2c3e50;
  --accent-color: #3498db;
  --nav-hover: #2980b9;
  --border-color: #eee;
  --secondary-bg: #f8f9fa;
  --secondary-text: #666;
}

[data-theme="dark"] {
  --bg-color: #1f2937;
  --text-color: #e5e7eb;
  --accent-color: #60a5fa;
  --nav-hover: #93c5fd;
  --border-color: #374151;
  --secondary-bg: #111827;
  --secondary-text: #9ca3af;
}

body {
  font-family: -apple-system, system-ui, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--bg-color);
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem;
  transition:
    background-color 0.3s ease,
    color 0.3s ease;
}

nav {
  padding: 1rem 0;
}

.site-nav {
  margin-bottom: 3rem;
}

nav a {
  margin-right: 1rem;
  text-decoration: none;
  color: #0366d6;
}

.nav-link {
  margin-right: 1.5rem;
  color: var(--accent-color);
  text-decoration: none;
}

.nav-link:hover {
  text-decoration: underline;
}

.hero {
  padding: 4rem 0;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  color: var(--text-color);
}

h2 {
  color: var(--text-color);
  margin-top: 2rem;
}

h3 {
  color: var(--text-color);
}

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

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

.content {
  margin: 2rem 0;
  background-color: var(--bg-color);
  padding: 2rem;
  border-radius: 8px;
}

ul {
  list-style-type: none;
  padding: 0;
}

li {
  margin: 0.5rem 0;
}

footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
  color: var(--secondary-text);
}

.theme-switch {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  padding: 0.75rem;
  border-radius: 1.5rem;
  border: 1px solid var(--border-color);
  background: var(--secondary-bg);
  color: var(--text-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  transition: all 0.3s ease;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.theme-switch:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.theme-switch .icon {
  font-size: 1.2rem;
  transition: transform 0.3s ease;
  display: inline-block;
}

.project-card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  margin-bottom: 1rem;
  background: var(--secondary-bg);
}

.article-list {
  list-style: none;
  padding: 0;
}

.article-list li {
  margin-bottom: 2rem;
}

.article-date {
  color: var(--secondary-text);
  font-size: 0.9rem;
}