:root {
  --bg: #0B0D10;
  --surface: #111418;
  --border: #23272F;
  --text: #F5F7FA;
  --text-secondary: #B5BCC8;
  --accent: #4F8CFF;
  --accent-hover: #6BA1FF;
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
}

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

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-size: 19px;
  line-height: 1.9;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s;
}

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

img {
  max-width: 100%;
  display: block;
}

::selection {
  background: var(--accent);
  color: var(--bg);
}

/* Progress bar */
#reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  background: var(--accent);
  width: 0;
  z-index: 100;
  transition: width 0.1s linear;
}

/* Container */
.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  padding: 0.75rem 0;
}

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

.logo {
  color: var(--text);
  font-weight: 600;
  font-size: 1rem;
  display: flex;
  align-items: baseline;
  gap: 0;
}

.logo-domain {
  font-size: 0.7em;
  font-weight: 400;
  color: var(--text-secondary);
  margin-left: 0.05em;
}

nav {
  display: flex;
  gap: 0.25rem;
}

nav a {
  padding: 0.35rem 0.7rem;
  border-radius: 0.4rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: background 0.15s, color 0.15s;
}

nav a:hover {
  background: var(--surface);
  color: var(--text);
}

#nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: 0.4rem;
  padding: 0.4rem;
  cursor: pointer;
  color: var(--text-secondary);
}

@media (max-width: 640px) {
  #nav-toggle {
    display: block;
  }

  nav {
    display: none;
  }

  #mobile-menu.open {
    display: flex;
  }

  .container {
    padding: 0 1.25rem;
  }

  main {
    padding: 2rem 0 3rem;
  }

  .article-content {
    font-size: 17px;
  }

  .article-content h1 {
    font-size: 1.6rem;
  }

  .article-content h2 {
    font-size: 1.25rem;
  }

  .post-nav {
    flex-direction: column;
  }

  .post-nav a {
    min-width: 0;
  }

  .post-item {
    padding: 0.85rem 1rem;
  }
}

#mobile-menu {
  display: none;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.5rem 1.5rem 0.75rem;
  border-top: 1px solid var(--border);
}

#mobile-menu a {
  padding: 0.4rem 0.7rem;
  border-radius: 0.4rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

#mobile-menu a:hover {
  background: var(--surface);
  color: var(--text);
}

/* Main */
main {
  padding: 4rem 0 6rem;
}

/* Article content: serif font */
.article-content {
  font-family: 'Literata', Georgia, 'Times New Roman', serif;
  font-size: 19px;
  line-height: 1.9;
  color: var(--text);
  font-weight: 400;
}

.article-content h1,
.article-content h2,
.article-content h3,
.article-content h4 {
  font-family: 'Inter', -apple-system, sans-serif;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
  line-height: 1.35;
}

.article-content h1 {
  font-size: 2.25rem;
  margin-top: 0;
  margin-bottom: 1rem;
}

.article-content h2 {
  font-size: 1.5rem;
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
}

.article-content h3 {
  font-size: 1.2rem;
  margin-top: 2rem;
  margin-bottom: 0.5rem;
}

.article-content p {
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
}

.article-content h2 + p,
.article-content h3 + p {
  color: var(--text-secondary);
}

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

.article-content li {
  margin-bottom: 0.35rem;
}

.article-content li p {
  margin-bottom: 0.35rem;
}

.article-content blockquote {
  margin: 2rem 0;
  padding: 1rem 1.25rem;
  border-left: 3px solid var(--accent);
  background: var(--surface);
  border-radius: 0.5rem;
  color: var(--text);
}

.article-content blockquote p {
  color: var(--text);
  margin-bottom: 0;
}

.article-content a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

.article-content img {
  border-radius: 0.75rem;
  margin: 2rem auto;
  box-shadow: 0 4px 24px rgba(0,0,0,0.3);
}

.article-content pre {
  margin: 2rem 0;
  padding: 1.25rem;
  background: #080a0d;
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  overflow-x: auto;
  font-size: 0.875rem;
  line-height: 1.7;
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
}

.article-content pre code {
  background: none;
  padding: 0;
  border-radius: 0;
  font-size: inherit;
  color: var(--text);
}

.article-content code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  background: var(--surface);
  padding: 0.15rem 0.4rem;
  border-radius: 0.35rem;
  font-size: 0.85em;
  color: var(--text);
}

.article-content h2 .anchor,
.article-content h3 .anchor {
  opacity: 0;
  margin-left: 0.25rem;
  font-weight: 400;
  color: var(--accent);
  text-decoration: none;
  font-size: 0.85em;
  transition: opacity 0.15s;
}

.article-content h2:hover .anchor,
.article-content h3:hover .anchor {
  opacity: 1;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 2rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-family: 'Inter', sans-serif;
}

.breadcrumb a {
  color: var(--text-secondary);
  transition: color 0.15s;
}

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

.breadcrumb span {
  color: var(--border);
}

/* Post header */
.post-header {
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
}

.post-header time {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.post-header .post-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.4rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.post-header .post-meta .sep {
  color: var(--border);
}

.post-header .post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
}

.post-header .post-tags a {
  display: inline-block;
  padding: 0.15rem 0.6rem;
  border-radius: 0.3rem;
  font-size: 0.75rem;
  font-family: 'Inter', sans-serif;
  background: var(--surface);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  transition: background 0.15s, color 0.15s;
  text-decoration: none;
}

.post-header .post-tags a:hover {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}

/* Post navigation */
.post-nav {
  display: flex;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.post-nav a {
  flex: 1;
  padding: 1rem 1.25rem;
  background: var(--surface);
  border-radius: 0.75rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  transition: box-shadow 0.15s;
}

.post-nav a:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.post-nav .nav-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-family: 'Inter', sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
}

.post-nav .nav-title {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
}

/* Home page */
.home-hero {
  margin-bottom: 3.5rem;
}

.home-hero h1 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
}

.home-hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.section-head h2 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 0;
}

.section-head a {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

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

.post-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.post-item {
  display: block;
  padding: 1rem 1.25rem;
  background: var(--surface);
  border-radius: 0.75rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  transition: box-shadow 0.15s;
  color: var(--text);
}

.post-item:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  color: var(--text);
}

.post-item-date {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.2rem;
}

.post-item-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.post-item-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Back link */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 2.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-family: 'Inter', sans-serif;
}

.back-link:hover {
  color: var(--accent);
}

/* TOC */
.toc {
  margin-bottom: 2.5rem;
  padding: 1.25rem 1.5rem;
  background: var(--surface);
  border-radius: 0.75rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem;
}

.toc-title {
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.5rem;
}

.toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.toc li {
  margin-bottom: 0.25rem;
  line-height: 1.5;
}

.toc a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s;
}

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

/* Copy button */
.article-content pre {
  position: relative;
}

.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.25rem 0.6rem;
  font-family: 'Inter', sans-serif;
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.35rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s, background 0.15s, color 0.15s;
}

.article-content pre:hover .copy-btn {
  opacity: 1;
}

.copy-btn:hover {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}

.code-lang {
  position: absolute;
  top: 0.5rem;
  left: 0.75rem;
  font-family: 'Inter', sans-serif;
  font-size: 0.7rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Responsive tables */
.table-wrapper {
  overflow-x: auto;
  margin: 1.5rem 0;
}

.table-wrapper table {
  width: 100%;
  border-collapse: collapse;
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem;
}

.table-wrapper th,
.table-wrapper td {
  padding: 0.6rem 0.75rem;
  border: 1px solid var(--border);
  text-align: left;
}

.table-wrapper th {
  background: var(--surface);
  color: var(--text);
  font-weight: 600;
}

.table-wrapper td {
  color: var(--text-secondary);
}

/* Related posts */
.related-posts {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.related-posts h2 {
  font-family: 'Inter', sans-serif;
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.75rem;
}

.related-posts .post-list {
  gap: 0.4rem;
}

/* Search */
.search-box {
  position: relative;
  margin-bottom: 1.5rem;
}

.search-box input {
  width: 100%;
  padding: 0.65rem 1rem;
  background: var(--surface);
  border: none;
  border-radius: 0.5rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  color: var(--text);
  font-family: 'Inter', sans-serif;
  font-size: 0.9rem;
  outline: none;
  transition: box-shadow 0.15s;
}

.search-box input:focus {
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.search-box input::placeholder {
  color: var(--text-secondary);
}

.search-hidden {
  display: none !important;
}

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