/* Runlevel — engineering notes. Static blog stylesheet. */

/* ---------- Fonts (self-hosted) ---------- */
@font-face {
  font-family: 'Inter';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('/static/inter-400.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('/static/inter-500.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: url('/static/inter-600.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: url('/static/inter-700.woff2') format('woff2');
}
@font-face {
  font-family: 'JetBrains Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('/static/jbmono-400.woff2') format('woff2');
}
@font-face {
  font-family: 'JetBrains Mono';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('/static/jbmono-500.woff2') format('woff2');
}

/* ---------- Theme tokens ---------- */
:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Menlo, Consolas, monospace;

  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --bg-elev: #ffffff;
  --border: #e4e8ec;
  --border-strong: #d0d7de;
  --text: #1f2328;
  --text-soft: #57606a;
  --text-faint: #8b949e;
  --accent: #2f6feb;
  --accent-soft: rgba(47, 111, 235, 0.1);
  --tag-bg: #eef2f6;
  --tag-text: #445;
  --code-bg: #f6f8fa;
  --code-border: #e4e8ec;
  --shadow: 0 1px 2px rgba(27, 31, 36, 0.06), 0 3px 12px rgba(27, 31, 36, 0.04);
  --radius: 10px;
  --maxw: 1080px;
}

:root[data-theme='dark'] {
  --bg: #0d1117;
  --bg-soft: #12161d;
  --bg-elev: #161b22;
  --border: #232a33;
  --border-strong: #30363d;
  --text: #e6edf3;
  --text-soft: #9aa5b1;
  --text-faint: #6e7781;
  --accent: #4d8bf5;
  --accent-soft: rgba(77, 139, 245, 0.14);
  --tag-bg: #1b2129;
  --tag-text: #adbac7;
  --code-bg: #0b0f14;
  --code-border: #232a33;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 16px rgba(0, 0, 0, 0.3);
}

/* Respect system preference before any explicit toggle */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #0d1117;
    --bg-soft: #12161d;
    --bg-elev: #161b22;
    --border: #232a33;
    --border-strong: #30363d;
    --text: #e6edf3;
    --text-soft: #9aa5b1;
    --text-faint: #6e7781;
    --accent: #4d8bf5;
    --accent-soft: rgba(77, 139, 245, 0.14);
    --tag-bg: #1b2129;
    --tag-text: #adbac7;
    --code-bg: #0b0f14;
    --code-border: #232a33;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 16px rgba(0, 0, 0, 0.3);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(150%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px;
  height: 60px;
  display: flex;
  align-items: center;
  gap: 20px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  color: var(--text);
  letter-spacing: -0.02em;
}
.logo:hover { text-decoration: none; }
.logo .mark {
  width: 30px; height: 30px;
  border-radius: 8px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, var(--accent), #7b5cff);
  color: #fff;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 15px;
}
.logo .dot { color: var(--accent); }
.nav {
  display: flex;
  gap: 4px;
  margin-left: 8px;
}
.nav a {
  color: var(--text-soft);
  font-size: 14px;
  font-weight: 500;
  padding: 6px 10px;
  border-radius: 6px;
}
.nav a:hover { background: var(--bg-soft); color: var(--text); text-decoration: none; }
.header-spacer { flex: 1; }
.search {
  position: relative;
  display: flex;
  align-items: center;
}
.search input {
  font-family: var(--font-sans);
  font-size: 13px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 7px 12px 7px 32px;
  width: 200px;
  outline: none;
}
.search input:focus { border-color: var(--accent); }
.search svg { position: absolute; left: 10px; width: 15px; height: 15px; color: var(--text-faint); }
.icon-btn {
  width: 36px; height: 36px;
  display: grid; place-items: center;
  border: 1px solid var(--border);
  background: var(--bg-soft);
  color: var(--text-soft);
  border-radius: 8px;
  cursor: pointer;
}
.icon-btn:hover { color: var(--text); border-color: var(--border-strong); }
.icon-btn svg { width: 18px; height: 18px; }
.theme-toggle .sun { display: none; }
:root[data-theme='dark'] .theme-toggle .sun { display: block; }
:root[data-theme='dark'] .theme-toggle .moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) .theme-toggle .sun { display: block; }
  :root:not([data-theme='light']) .theme-toggle .moon { display: none; }
}

/* ---------- Layout ---------- */
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
  padding: 32px 20px 80px;
  max-width: var(--maxw);
  margin: 0 auto;
}
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { display: none; }
}

/* ---------- Hero / page intro ---------- */
.page-intro { padding: 40px 0 8px; }
.page-intro h1 {
  font-size: 32px;
  letter-spacing: -0.03em;
  margin: 0 0 6px;
}
.page-intro p { color: var(--text-soft); margin: 0; font-size: 16px; }

.filter-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  padding: 20px 0 4px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 8px;
}
.chip {
  font-size: 13px;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg-soft);
  color: var(--text-soft);
  cursor: pointer;
}
.chip:hover { border-color: var(--border-strong); color: var(--text); }
.chip.active { background: var(--accent); color: #fff; border-color: var(--accent); }

/* ---------- Article list ---------- */
.post-list { display: flex; flex-direction: column; }
.post-card {
  display: flex;
  gap: 20px;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}
.post-card .body { flex: 1; min-width: 0; }
.post-meta-top {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
  font-size: 13px;
  color: var(--text-soft);
}
.avatar {
  border-radius: 50%;
  flex-shrink: 0;
  display: inline-grid;
  place-items: center;
  color: #fff;
  font-weight: 600;
  font-family: var(--font-sans);
  user-select: none;
}
.post-meta-top .avatar { width: 24px; height: 24px; font-size: 11px; }
.post-card h2 {
  font-size: 21px;
  line-height: 1.3;
  letter-spacing: -0.02em;
  margin: 0 0 6px;
}
.post-card h2 a { color: var(--text); }
.post-card h2 a:hover { color: var(--accent); text-decoration: none; }
.post-card .excerpt {
  color: var(--text-soft);
  font-size: 15px;
  margin: 0 0 14px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.post-meta-bottom {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  font-size: 13px;
  color: var(--text-faint);
}
.tags { display: flex; gap: 6px; flex-wrap: wrap; }
.tag {
  font-size: 12px;
  font-weight: 500;
  padding: 3px 9px;
  border-radius: 6px;
  background: var(--tag-bg);
  color: var(--tag-text);
}
.tag:hover { text-decoration: none; color: var(--accent); }
.meta-dot::before { content: '·'; margin-right: 14px; color: var(--text-faint); }
.post-thumb {
  width: 128px; height: 96px;
  border-radius: var(--radius);
  flex-shrink: 0;
  display: grid; place-items: center;
  overflow: hidden;
  border: 1px solid var(--border);
}
@media (max-width: 640px) {
  .post-thumb { display: none; }
  .post-card h2 { font-size: 19px; }
}

/* ---------- Sidebar ---------- */
.sidebar { display: flex; flex-direction: column; gap: 24px; }
.widget {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
}
.widget h3 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-faint);
  margin: 0 0 14px;
}
.trending-item {
  display: flex;
  gap: 12px;
  padding: 8px 0;
}
.trending-item .num {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 500;
  color: var(--text-faint);
  line-height: 1.2;
}
.trending-item a { color: var(--text); font-size: 14px; font-weight: 500; line-height: 1.35; }
.trending-item a:hover { color: var(--accent); text-decoration: none; }
.trending-item .sub { font-size: 12px; color: var(--text-faint); margin-top: 3px; }
.tagcloud { display: flex; flex-wrap: wrap; gap: 8px; }
.about-widget p { font-size: 14px; color: var(--text-soft); margin: 0 0 12px; }
.btn {
  display: inline-block;
  font-size: 14px;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  border: none;
  cursor: pointer;
}
.btn:hover { text-decoration: none; opacity: 0.92; }
.btn.ghost { background: transparent; border: 1px solid var(--border-strong); color: var(--text); }

/* ---------- Article page ---------- */
.article-wrap { max-width: 760px; margin: 0 auto; padding: 0 20px; }
.reading-bar {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), #7b5cff);
  z-index: 60;
  transition: width 0.1s linear;
}
.article-header { padding: 40px 0 24px; }
.breadcrumb { font-size: 13px; color: var(--text-faint); margin-bottom: 18px; }
.breadcrumb a { color: var(--text-soft); }
.article-header h1 {
  font-size: 38px;
  line-height: 1.2;
  letter-spacing: -0.03em;
  margin: 0 0 12px;
}
.article-header .subtitle {
  font-size: 19px;
  color: var(--text-soft);
  margin: 0 0 24px;
  line-height: 1.5;
}
.byline {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.byline .avatar { width: 44px; height: 44px; font-size: 16px; }
.byline .who { flex: 1; }
.byline .name { font-weight: 600; font-size: 15px; }
.byline .name a { color: var(--text); }
.byline .sub { font-size: 13px; color: var(--text-faint); margin-top: 2px; }
.byline .actions { display: flex; gap: 8px; }

/* ---------- Article body typography ---------- */
.article-body {
  font-size: 18px;
  line-height: 1.75;
  color: var(--text);
  padding: 8px 0 40px;
}
.article-body > *:first-child { margin-top: 0; }
.article-body h2 {
  font-size: 26px;
  letter-spacing: -0.02em;
  margin: 44px 0 14px;
  padding-bottom: 6px;
}
.article-body h3 { font-size: 20px; margin: 32px 0 10px; }
.article-body p { margin: 0 0 20px; }
.article-body ul, .article-body ol { margin: 0 0 20px; padding-left: 26px; }
.article-body li { margin: 6px 0; }
.article-body a { text-decoration: underline; text-underline-offset: 2px; }
.article-body strong { font-weight: 600; }
.article-body blockquote {
  margin: 24px 0;
  padding: 4px 20px;
  border-left: 3px solid var(--accent);
  color: var(--text-soft);
  background: var(--accent-soft);
  border-radius: 0 8px 8px 0;
}
.article-body blockquote p:last-child { margin-bottom: 0; }
.article-body img, .article-body svg { max-width: 100%; }

/* inline code */
.article-body :not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 5px;
  padding: 1px 5px;
}

/* code blocks */
.article-body pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius);
  padding: 0;
  margin: 0 0 24px;
  overflow: hidden;
}
.code-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  border-bottom: 1px solid var(--code-border);
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-faint);
  background: color-mix(in srgb, var(--code-bg) 60%, var(--bg-soft));
}
.copy-btn {
  font-family: var(--font-sans);
  font-size: 12px;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-soft);
  border-radius: 6px;
  padding: 2px 8px;
  cursor: pointer;
}
.copy-btn:hover { color: var(--text); border-color: var(--border-strong); }
.article-body pre code.hljs {
  display: block;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.6;
  padding: 14px 16px;
  overflow-x: auto;
  background: transparent;
}

/* figure / diagrams */
.figure {
  margin: 28px 0;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-soft);
  text-align: center;
}
.figure svg { width: 100%; height: auto; }
.figure figcaption {
  margin-top: 12px;
  font-size: 13px;
  color: var(--text-faint);
}

.diagram-label { font-family: var(--font-mono); font-size: 12px; }
.diagram-box-text { font-family: var(--font-sans); font-size: 13px; font-weight: 500; }

/* article footer tags + share */
.article-tags { display: flex; gap: 8px; flex-wrap: wrap; margin: 8px 0 32px; }
.article-tags .tag { font-size: 13px; padding: 5px 12px; }

.author-card {
  display: flex;
  gap: 16px;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-soft);
  margin: 32px 0;
}
.author-card .avatar { width: 56px; height: 56px; font-size: 20px; }
.author-card .name { font-weight: 700; font-size: 17px; }
.author-card .bio { font-size: 14px; color: var(--text-soft); margin-top: 6px; }

/* ---------- Comments ---------- */
.comments { margin: 48px 0; }
.comments h2 { font-size: 20px; margin: 0 0 20px; }
.comment-form {
  display: flex;
  gap: 12px;
  margin-bottom: 32px;
}
.comment-form textarea {
  flex: 1;
  font-family: var(--font-sans);
  font-size: 15px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-elev);
  color: var(--text);
  resize: vertical;
  min-height: 44px;
  outline: none;
}
.comment-form textarea:focus { border-color: var(--accent); }
.comment {
  display: flex;
  gap: 12px;
  padding: 18px 0;
  border-top: 1px solid var(--border);
}
.comment .avatar { width: 36px; height: 36px; font-size: 14px; }
.comment .c-body { flex: 1; }
.comment .c-head { display: flex; align-items: center; gap: 8px; font-size: 14px; }
.comment .c-name { font-weight: 600; }
.comment .c-time { color: var(--text-faint); font-size: 12px; }
.comment .c-text { font-size: 15px; margin: 6px 0 8px; color: var(--text); }
.comment .c-actions { display: flex; gap: 16px; font-size: 13px; color: var(--text-faint); }
.comment .c-actions span { cursor: pointer; }
.comment .c-actions span:hover { color: var(--accent); }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-soft);
  margin-top: 40px;
}
.footer-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 20px;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 32px;
}
@media (max-width: 640px) { .footer-inner { grid-template-columns: 1fr; } }
.footer-inner h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-faint); margin: 0 0 12px; }
.footer-inner a { display: block; color: var(--text-soft); font-size: 14px; padding: 4px 0; }
.footer-inner a:hover { color: var(--accent); text-decoration: none; }
.footer-brand p { color: var(--text-soft); font-size: 14px; max-width: 320px; }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 18px 20px;
  text-align: center;
  font-size: 13px;
  color: var(--text-faint);
}

/* loading / states */
.skeleton { color: var(--text-faint); padding: 60px 0; text-align: center; }

/* ---------- highlight.js theme (self-contained) ---------- */
.hljs { color: var(--text); background: transparent; }
:root .hljs-comment, :root .hljs-quote { color: #6a737d; font-style: italic; }
:root .hljs-keyword, :root .hljs-selector-tag, :root .hljs-built_in, :root .hljs-name, :root .hljs-tag { color: #cf222e; }
:root .hljs-string, :root .hljs-title, :root .hljs-section, :root .hljs-attribute, :root .hljs-literal, :root .hljs-template-tag, :root .hljs-template-variable, :root .hljs-type, :root .hljs-addition { color: #0a7d33; }
:root .hljs-number, :root .hljs-symbol, :root .hljs-bullet, :root .hljs-link { color: #0550ae; }
:root .hljs-title.function_, :root .hljs-function .hljs-title { color: #6639ba; }
:root .hljs-attr, :root .hljs-variable, :root .hljs-params { color: #953800; }
:root .hljs-meta { color: #6a737d; }
:root .hljs-deletion { color: #cf222e; }

:root[data-theme='dark'] .hljs-comment, :root[data-theme='dark'] .hljs-quote { color: #8b949e; }
:root[data-theme='dark'] .hljs-keyword, :root[data-theme='dark'] .hljs-selector-tag, :root[data-theme='dark'] .hljs-built_in, :root[data-theme='dark'] .hljs-name, :root[data-theme='dark'] .hljs-tag { color: #ff7b72; }
:root[data-theme='dark'] .hljs-string, :root[data-theme='dark'] .hljs-title, :root[data-theme='dark'] .hljs-section, :root[data-theme='dark'] .hljs-attribute, :root[data-theme='dark'] .hljs-literal, :root[data-theme='dark'] .hljs-template-tag, :root[data-theme='dark'] .hljs-template-variable, :root[data-theme='dark'] .hljs-type, :root[data-theme='dark'] .hljs-addition { color: #7ee787; }
:root[data-theme='dark'] .hljs-number, :root[data-theme='dark'] .hljs-symbol, :root[data-theme='dark'] .hljs-bullet, :root[data-theme='dark'] .hljs-link { color: #79c0ff; }
:root[data-theme='dark'] .hljs-title.function_, :root[data-theme='dark'] .hljs-function .hljs-title { color: #d2a8ff; }
:root[data-theme='dark'] .hljs-attr, :root[data-theme='dark'] .hljs-variable, :root[data-theme='dark'] .hljs-params { color: #ffa657; }
:root[data-theme='dark'] .hljs-meta { color: #8b949e; }

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) .hljs-comment, :root:not([data-theme='light']) .hljs-quote { color: #8b949e; }
  :root:not([data-theme='light']) .hljs-keyword, :root:not([data-theme='light']) .hljs-built_in, :root:not([data-theme='light']) .hljs-name, :root:not([data-theme='light']) .hljs-tag { color: #ff7b72; }
  :root:not([data-theme='light']) .hljs-string, :root:not([data-theme='light']) .hljs-title, :root:not([data-theme='light']) .hljs-literal, :root:not([data-theme='light']) .hljs-type, :root:not([data-theme='light']) .hljs-attribute { color: #7ee787; }
  :root:not([data-theme='light']) .hljs-number, :root:not([data-theme='light']) .hljs-symbol, :root:not([data-theme='light']) .hljs-link { color: #79c0ff; }
  :root:not([data-theme='light']) .hljs-title.function_ { color: #d2a8ff; }
  :root:not([data-theme='light']) .hljs-attr, :root:not([data-theme='light']) .hljs-variable, :root:not([data-theme='light']) .hljs-params { color: #ffa657; }
}