:root {
  --fg: #1a1a1a;
  --fg-secondary: #636363;
  --bg: #fff;
  --bg-code: #f5f5f5;
  --bg-card-hover: #f4f4f4;
  --bg-button-secondary: #f8f8f8;
  --border: #e0e0e0;
  --border-light: #eee;
  --accent: #0055aa;
  --accent-dark: #004488;
  --accent-muted: rgba(0, 85, 170, 0.08);
  --accent-subtle: rgba(0, 85, 170, 0.04);
  --focus-ring: rgba(0, 85, 170, 0.35);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-card-hover: 0 4px 12px rgba(0, 0, 0, 0.08);
  --font-mono: 'SF Mono', 'Cascadia Code', 'Fira Code', Consolas, monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --max-width: 720px;
  --max-width-wide: 960px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e0e0e0;
    --fg-secondary: #999;
    --bg: #161616;
    --bg-code: #1e1e1e;
    --bg-card-hover: #1e1e1e;
    --bg-button-secondary: #1f1f1f;
    --border: #2a2a2a;
    --border-light: #222;
    --accent: #6db3f2;
    --accent-dark: #5a9de0;
    --accent-muted: rgba(109, 179, 242, 0.06);
    --accent-subtle: rgba(109, 179, 242, 0.03);
    --focus-ring: rgba(109, 179, 242, 0.35);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.2);
    --shadow-card-hover: 0 4px 12px rgba(0, 0, 0, 0.3);
  }
}

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

html {
  font-size: 17px;
  line-height: 1.7;
}

body {
  font-family: var(--font-sans);
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 3px;
  border-radius: 4px;
}

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

/* Header */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 1.5rem 0;
  margin-bottom: 3.5rem;
}

.site-header .container {
  max-width: var(--max-width-wide);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--fg);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-nav {
  display: flex;
  gap: 1.5rem;
}

.site-nav a {
  color: var(--fg-secondary);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

.site-nav a:hover {
  color: var(--fg);
}

/* Site intro (landing page) — hero section */
.site-intro {
  max-width: var(--max-width-wide);
  margin: 0 auto 3rem;
  padding: 2.5rem 2rem 2rem;
  background: var(--accent-subtle);
  border-radius: 12px;
  border: 1px solid var(--border-light);
}

.intro-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.intro-title {
  font-size: 2.25rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
  text-wrap: balance;
}

.intro-body {
  max-width: 680px;
}

.intro-body p {
  color: var(--fg-secondary);
  margin-bottom: 0.75rem;
  line-height: 1.7;
  font-size: 0.95rem;
}

.intro-body p:last-child {
  margin-bottom: 0;
}

.intro-audience {
  color: var(--fg);
  font-weight: 500;
}

.intro-body a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.intro-body a:hover {
  text-decoration: underline;
}

.intro-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.6rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  padding: 0.6rem 1.25rem;
  border: 1px solid transparent;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease, transform 0.1s ease, box-shadow 0.15s ease;
}

.button-primary {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}

.button-primary:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
  transform: translateY(-1px);
  box-shadow: 0 2px 6px rgba(0, 85, 170, 0.2);
}

.button-primary:active {
  transform: translateY(0);
  box-shadow: none;
}

.button-secondary {
  color: var(--fg);
  background: var(--bg-button-secondary);
  border-color: var(--border);
}

.button-secondary:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.button-secondary:active {
  transform: translateY(0);
}

.trust-bar {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.5rem;
  list-style: none;
  margin-top: 1.5rem;
}

.trust-bar li {
  font-size: 0.77rem;
  color: var(--fg-secondary);
  border: 1px solid var(--border);
  background: var(--bg);
  border-left: 3px solid var(--accent);
  border-radius: 6px;
  padding: 0.5rem 0.65rem 0.5rem 0.75rem;
  line-height: 1.4;
  font-weight: 500;
}

/* Article cards (index) */
.articles {
  margin-bottom: 2.5rem;
}

.articles-intro {
  margin-bottom: 1.25rem;
}

.articles-heading {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-secondary);
  margin-bottom: 0.35rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
}

.articles-subheading {
  color: var(--fg-secondary);
  font-size: 0.84rem;
}

.article-card {
  display: block;
  position: relative;
  margin-bottom: 0.75rem;
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 6px;
  box-shadow: var(--shadow-card);
  transition: border-color 0.15s ease, background-color 0.15s ease, box-shadow 0.2s ease, transform 0.15s ease;
}

.article-card:hover,
.article-card:focus-within {
  border-color: var(--accent);
  background-color: var(--bg-card-hover);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-1px);
}

.article-card-link {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0 1.5rem;
  color: inherit;
  text-decoration: none;
  padding: 1.5rem;
}

.article-part-number {
  grid-row: 1 / -1;
  display: flex;
  align-items: center;
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--accent);
  opacity: 0.15;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  padding-right: 0.25rem;
}

.article-card-content {
  min-width: 0;
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.35rem;
}

.article-part {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
}

.article-date {
  font-size: 0.8rem;
  color: var(--fg-secondary);
  font-variant-numeric: tabular-nums;
}

.article-reading-time {
  font-size: 0.78rem;
  color: var(--fg-secondary);
}

.article-meta-sep {
  color: var(--border);
  font-size: 0.7rem;
}

.article-title {
  font-size: 1.15rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 0.5rem;
  color: var(--fg);
}

.article-card:hover .article-title,
.article-card:focus-within .article-title {
  color: var(--accent);
}

.article-description {
  font-size: 0.9rem;
  color: var(--fg-secondary);
  line-height: 1.55;
  margin-bottom: 0.75rem;
}

.article-tags {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.article-tag {
  display: inline-block;
  font-size: 0.76rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-muted);
  padding: 0.16rem 0.5rem;
  border-radius: 3px;
  letter-spacing: 0.01em;
}

/* Organizational identity section */
.site-about {
  border-top: 1px solid var(--border-light);
  padding: 2rem 0 0.5rem;
  margin-top: 0.5rem;
}

.site-about-heading {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-secondary);
  margin-bottom: 0.65rem;
}

.site-about p {
  font-size: 0.88rem;
  color: var(--fg-secondary);
  line-height: 1.65;
  max-width: 640px;
}

.site-about a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.site-about a:hover {
  text-decoration: underline;
}

/* Coda (bottom section) */
.site-coda {
  border-top: 1px solid var(--border-light);
  padding: 1.8rem 0 0.5rem;
  font-size: 0.88rem;
  color: var(--fg-secondary);
  line-height: 1.6;
}

.site-coda a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.site-coda a:hover {
  text-decoration: underline;
}

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

.post-title {
  font-size: 1.75rem;
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

.post-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

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

.post-reading-time {
  font-size: 0.88rem;
  color: var(--fg-secondary);
}

.post-meta-sep {
  color: var(--border);
  font-size: 0.7rem;
}

.post-part {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.25rem;
}

.post-series {
  font-size: 0.9rem;
  color: var(--fg-secondary);
  margin-top: 0.25rem;
}

.post-series a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.post-series a:hover {
  text-decoration: underline;
}

.post-content h2 {
  font-size: 1.35rem;
  font-weight: 600;
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
}

.post-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.5rem;
}

.post-content p {
  margin-bottom: 1.25rem;
}

.post-content ul, .post-content ol {
  margin-bottom: 1.25rem;
  padding-left: 1.5rem;
}

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

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

.post-content a:hover {
  text-decoration: underline;
}

/* Code */
.post-content code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--bg-code);
  padding: 0.15em 0.35em;
  border-radius: 3px;
}

.post-content pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  line-height: 1.5;
}

.post-content pre code {
  background: none;
  padding: 0;
  border-radius: 0;
  font-size: 0.85em;
}

/* Tables */
.post-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
}

.post-content th, .post-content td {
  border: 1px solid var(--border);
  padding: 0.5rem 0.75rem;
  text-align: left;
}

.post-content th {
  background: var(--bg-code);
  font-weight: 600;
}

/* Blockquote */
.post-content blockquote {
  border-left: 3px solid var(--border);
  padding-left: 1rem;
  color: var(--fg-secondary);
  margin-bottom: 1.25rem;
}

/* Strong/em */
.post-content strong {
  font-weight: 600;
}

/* Series navigation (post pages) */
.series-nav {
  border-top: 1px solid var(--border);
  margin-top: 3rem;
  padding-top: 1.5rem;
}

.series-nav-heading {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-secondary);
  margin-bottom: 0.75rem;
}

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

.series-nav-link {
  flex: 1 1 0;
  min-width: 200px;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease, background-color 0.15s ease, box-shadow 0.15s ease;
}

.series-nav-link:hover {
  border-color: var(--accent);
  background-color: var(--bg-card-hover);
  box-shadow: var(--shadow-card);
}

.series-nav-direction {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.25rem;
}

.series-nav-title {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--fg);
  line-height: 1.35;
}

.series-nav-link:hover .series-nav-title {
  color: var(--accent);
}

.series-nav-link--next {
  text-align: right;
  margin-left: auto;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  margin-top: 4rem;
  font-size: 0.82rem;
  color: var(--fg-secondary);
}

.site-footer .container {
  max-width: var(--max-width-wide);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.footer-left {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.footer-tagline {
  font-size: 0.78rem;
  color: var(--fg-secondary);
}

.site-footer a {
  color: var(--fg-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.15s ease;
  overflow-wrap: anywhere;
}

.site-footer a:hover {
  color: var(--fg);
}

@media (max-width: 720px) {
  html {
    font-size: 16px;
  }

  .site-header {
    margin-bottom: 2.5rem;
    padding: 1.15rem 0;
  }

  .site-header .container {
    align-items: flex-start;
    flex-direction: column;
    gap: 0.65rem;
  }

  .site-intro {
    margin-left: 0;
    margin-right: 0;
    border-radius: 0;
    border-left: none;
    border-right: none;
    padding: 1.75rem 1.5rem 1.5rem;
  }

  .intro-title {
    font-size: 1.72rem;
  }

  .intro-actions {
    width: 100%;
  }

  .button {
    flex: 1 1 auto;
    min-width: 10.5rem;
  }

  .trust-bar {
    grid-template-columns: 1fr;
  }

  .article-card-link {
    grid-template-columns: 1fr;
    padding: 1.15rem;
  }

  .article-part-number {
    display: none;
  }

  .article-tag {
    font-size: 0.78rem;
  }

  .series-nav-links {
    flex-direction: column;
  }

  .series-nav-link--next {
    text-align: left;
  }

  .site-footer .container {
    flex-direction: column;
    align-items: flex-start;
  }
}