/* === Reset & Base === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #0d1117;
  --bg-secondary: #161b22;
  --border: #21262d;
  --text: #e6edf3;
  --text-secondary: #8b949e;
  --accent: #58a6ff;
  --accent-hover: #79c0ff;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --max-width: 800px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

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

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

/* === Layout === */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* === Nav === */
nav {
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 100;
}

nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
}

.nav-brand:hover {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: color 0.2s;
}

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

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.25rem;
}

/* === Hero === */
.hero {
  padding: 4rem 0 2rem;
}

.hero h1 {
  font-family: var(--font-mono);
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.hero .subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
  max-width: 600px;
}

.hero .links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.hero .links a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  transition: border-color 0.2s, color 0.2s;
}

.hero .links a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* === Sections === */
section {
  padding: 2rem 0;
}

section + section {
  border-top: 1px solid var(--border);
}

h2 {
  font-family: var(--font-mono);
  font-size: 1.3rem;
  margin-bottom: 1.5rem;
  color: var(--text);
}

h3 {
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
}

/* === Skills Grid === */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.skill-card {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
}

.skill-card h3 {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.skill-card ul {
  list-style: none;
}

.skill-card li {
  color: var(--text-secondary);
  font-size: 0.85rem;
  padding: 0.15rem 0;
}

/* === Education === */
.education-item {
  margin-bottom: 1rem;
}

.education-item h3 {
  font-size: 1rem;
  margin-bottom: 0.15rem;
}

.education-item .school {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* === Project Cards === */
.project-card {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.25rem;
}

.project-card h3 {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}

.project-card h3 a {
  color: var(--text);
}

.project-card h3 a:hover {
  color: var(--accent);
}

.project-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 0.75rem;
}

.project-links {
  display: flex;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.project-links a {
  font-size: 0.85rem;
  padding: 0.3rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: 4px;
}

.project-links a:hover {
  border-color: var(--accent);
}

.tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  background: rgba(88, 166, 255, 0.1);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

/* === Paper List === */
.paper-item {
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.paper-item:last-child {
  border-bottom: none;
}

.paper-item h3 {
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.paper-item .date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}

.paper-item p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 0.4rem;
}

/* === Post List === */
.post-item {
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.post-item:last-child {
  border-bottom: none;
}

.post-item h3 {
  margin-bottom: 0.25rem;
}

.post-item .date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}

.post-item p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* === Archive === */
.archive-group {
  margin-bottom: 2rem;
}

.archive-group h3 {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.archive-list {
  list-style: none;
}

.archive-list li {
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--border);
}

.archive-list li:last-child {
  border-bottom: none;
}

.archive-list .date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-left: 0.5rem;
}

/* === Footer === */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  margin-top: 2rem;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

/* === Responsive === */
@media (max-width: 640px) {
  .nav-toggle {
    display: block;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 1rem 1.5rem;
    gap: 0.75rem;
  }

  .nav-links.open {
    display: flex;
  }

  nav .container {
    position: relative;
  }

  .hero h1 {
    font-size: 1.5rem;
  }

  .hero .subtitle {
    font-size: 1rem;
  }

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

/* === Article page styles === */
.article-content {
  padding: 2rem 0;
}

.article-content h1 {
  font-family: var(--font-mono);
  font-size: 1.8rem;
  margin-bottom: 1rem;
}

.article-content h2 {
  margin-top: 2rem;
}

.article-content h3 {
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
}

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

.article-content img {
  max-width: 100%;
  border-radius: 8px;
  margin: 1rem 0;
}

.article-content blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 1rem;
  color: var(--text-secondary);
  font-style: italic;
  margin: 1rem 0;
}

.article-content code {
  font-family: var(--font-mono);
  background: var(--bg-secondary);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  font-size: 0.9em;
}

.article-content pre {
  background: var(--bg-secondary);
  padding: 1rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 1rem 0;
}

.article-content pre code {
  background: none;
  padding: 0;
}

.article-content ul, .article-content ol {
  margin: 1rem 0;
  padding-left: 1.5rem;
  color: var(--text-secondary);
}

.article-content li {
  margin-bottom: 0.4rem;
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.85rem;
}

.article-content th, .article-content td {
  border: 1px solid var(--border);
  padding: 0.5rem;
  text-align: left;
}

.article-content th {
  background: var(--bg-secondary);
  color: var(--text);
}

.article-content td {
  color: var(--text-secondary);
}