:root {
  --bg: #0d1117; --bg-surface: #161b22; --bg-elevated: #1c2128;
  --bg-code: #0d1117; --bg-tech: #0f1a14;
  --border: #30363d; --border-subtle: #21262d; --border-tech: #1f4a2e;
  --text: #e6edf3; --text-muted: #8b949e; --text-subtle: #6e7681;
  --accent: #f7931a; --accent-dim: #f7931a22; --accent-hover: #ffab40;
  --link: #58a6ff; --link-hover: #79c0ff;
  --green: #3fb950; --sidebar-w: 280px; --content-max: 820px;
  --header-h: 48px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
body { font-family: 'IBM Plex Sans', -apple-system, sans-serif; background: var(--bg); color: var(--text); font-size: 16px; line-height: 1.7; }
html, body { overflow-x: hidden; }
/* ─── Header Bar (always visible) ─── */
.site-nav {
  display: flex;
  position: fixed; top: 0; left: 0; right: 0; z-index: 200;
  background: var(--bg-surface); border-bottom: 1px solid var(--border);
  padding: 0 16px; height: var(--header-h); align-items: center;
}
.site-nav button {
  background: none; border: none; color: var(--text); font-size: 22px;
  cursor: pointer; padding: 4px 8px; line-height: 1;
}
.site-nav button:hover { color: var(--accent); }
.site-nav .brand {
  font-family: 'Space Grotesk', sans-serif; font-size: 15px; font-weight: 600;
  color: var(--accent); margin-left: 12px; text-decoration: none;
}
.site-nav .brand:hover { color: var(--accent-hover); text-decoration: none; }
/* Cross-page nav links (App / Protocol / Docs). Right-aligned via
   margin-left:auto on the container. */
.site-nav-links {
  display: flex; gap: 4px; margin-left: auto;
}
.site-nav-links .nav-link {
  font-family: 'Space Grotesk', sans-serif; font-size: 13px; font-weight: 500;
  color: var(--text-muted); text-decoration: none;
  padding: 6px 12px; border-radius: 5px;
  transition: all 0.15s;
}
.site-nav-links .nav-link:hover {
  color: var(--text); background: var(--bg-elevated); text-decoration: none;
}
.site-nav-links .nav-link-active {
  color: var(--accent); background: var(--accent-dim);
}
@media (max-width: 500px) {
  .site-nav-links .nav-link { padding: 6px 8px; font-size: 12px; }
}

/* ─── Sidebar ─── */
#toc {
  position: fixed; top: var(--header-h); left: 0; width: var(--sidebar-w);
  height: calc(100vh - var(--header-h)); overflow-y: auto;
  background: var(--bg-surface); border-right: 1px solid var(--border);
  padding: 16px 0; z-index: 100;
  scrollbar-width: thin; scrollbar-color: var(--border) transparent;
  transition: transform 0.25s ease;
}
#toc::-webkit-scrollbar { width: 4px; }
#toc::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }
#toc.collapsed { transform: translateX(-100%); }
.toc-header {
  font-family: 'Space Grotesk', sans-serif; font-size: 11px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 1.5px; color: var(--text-subtle);
  padding: 0 20px 12px; border-bottom: 1px solid var(--border-subtle); margin-bottom: 8px;
}
#toc ul { list-style: none; }
#toc li a {
  display: block; padding: 4px 20px; color: var(--text-muted); text-decoration: none;
  font-size: 13px; line-height: 1.5; border-left: 2px solid transparent; transition: all 0.15s;
}
#toc li a:hover { color: var(--text); background: var(--bg-elevated); }
#toc li a.active { color: var(--accent); border-left-color: var(--accent); background: var(--accent-dim); }
#toc li.toc-h3 a { padding-left: 32px; font-size: 12px; color: var(--text-subtle); }
#toc li.toc-h3 a:hover { color: var(--text-muted); }
#toc li.toc-h3 a.active { color: var(--accent); border-left-color: var(--accent); }
.toc-loading { padding: 20px; color: var(--text-subtle); font-size: 13px; }

/* ─── Main Content ─── */
#content {
  margin-left: var(--sidebar-w);
  padding: calc(var(--header-h) + 24px) 40px 120px;
  transition: margin-left 0.25s ease;
}
#content.expanded { margin-left: 0; }

/* ─── Site Header ─── */
.site-header { margin-bottom: 48px; padding-bottom: 32px; border-bottom: 1px solid var(--border); }
.site-header h1 { font-family: 'Space Grotesk', sans-serif; font-size: 42px; font-weight: 700; color: var(--accent); letter-spacing: -1px; margin-bottom: 8px; }
.subtitle { font-size: 20px; color: var(--text-muted); margin-bottom: 16px; }
.meta { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.badge { display: inline-block; padding: 4px 12px; border-radius: 20px; font-size: 12px; font-weight: 600; letter-spacing: 0.5px; }
.badge-draft { background: #f7931a22; color: var(--accent); border: 1px solid #f7931a44; }
.badge-version { background: var(--bg-elevated); color: var(--text-muted); border: 1px solid var(--border); }
.btn-contribute { display: inline-flex; align-items: center; gap: 8px; padding: 8px 20px; background: var(--bg-elevated); color: var(--accent); text-decoration: none; border-radius: 6px; font-size: 14px; font-weight: 600; font-family: 'Space Grotesk', sans-serif; border: 1px solid var(--accent); transition: all 0.2s; }
.btn-contribute:hover { background: var(--accent); color: #fff; text-decoration: none; }
.btn-contribute svg { width: 16px; height: 16px; }
.abstract { margin-top: 24px; padding: 20px 24px; background: var(--bg-surface); border: 1px solid var(--border); border-radius: 8px; font-size: 15px; color: var(--text-muted); line-height: 1.75; }
.abstract strong { color: var(--text); }
.loading-msg { color: var(--text-subtle); font-style: italic; }

/* ─── Typography ─── */
h2 { font-family: 'Space Grotesk', sans-serif; font-size: 28px; font-weight: 700; color: var(--text); margin-top: 56px; margin-bottom: 16px; padding-top: 24px; border-top: 1px solid var(--border-subtle); letter-spacing: -0.5px; }
h2:first-of-type { border-top: none; padding-top: 0; margin-top: 0; }
h3 { font-family: 'Space Grotesk', sans-serif; font-size: 20px; font-weight: 600; color: var(--text); margin-top: 36px; margin-bottom: 12px; }
p { margin-bottom: 16px; }
strong { font-weight: 600; }
a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; }
sup { font-size: 11px; color: var(--accent); font-weight: 500; }
code { font-family: 'JetBrains Mono', monospace; font-size: 13.5px; background: var(--bg-elevated); padding: 2px 6px; border-radius: 4px; border: 1px solid var(--border-subtle); color: #a5d6ff; }

/* ─── Code Blocks ─── */
pre { position: relative; margin: 20px 0 28px; background: var(--bg-code); border: 1px solid var(--border); border-radius: 8px; padding: 20px 24px; overflow-x: auto; line-height: 1.6; }
pre code { font-family: 'JetBrains Mono', monospace; font-size: 13px; color: var(--text-muted); background: none; border: none; padding: 0; }
.copy-btn { position: absolute; top: 10px; right: 10px; background: var(--bg-elevated); border: 1px solid var(--border); color: var(--text-subtle); padding: 6px 10px; border-radius: 5px; cursor: pointer; font-size: 12px; font-family: 'Space Grotesk', sans-serif; display: flex; align-items: center; gap: 4px; transition: all 0.2s; z-index: 2; }
.copy-btn:hover { color: var(--text); border-color: var(--text-subtle); background: var(--border); }
.copy-btn.copied { color: var(--green); border-color: var(--green); }

/* Technical blocks (text/protocol specs) get green accent */
pre.language-text { border-left: 3px solid var(--green); background: var(--bg-tech); }
pre.language-text code { color: #8fbfae; }

/* ─── Tables ─── */
table { width: 100%; border-collapse: collapse; margin: 16px 0 24px; font-size: 14px; }
th { background: var(--bg-elevated); color: var(--text); font-weight: 600; text-align: left; padding: 10px 14px; border: 1px solid var(--border); font-family: 'Space Grotesk', sans-serif; font-size: 13px; }
td { padding: 8px 14px; border: 1px solid var(--border-subtle); color: var(--text-muted); }
tr:nth-child(even) td { background: var(--bg-surface); }

/* ─── Mobile ─── */
@media (max-width: 900px) {
  #toc { width: 260px; transform: translateX(-100%); }
  #toc.open { transform: translateX(0); box-shadow: 4px 0 24px rgba(0,0,0,0.5); }
  #toc.collapsed { transform: translateX(-100%); }
  #content { margin-left: 0; padding-left: 20px; padding-right: 20px; }
  #content.expanded { margin-left: 0; }
}
/* ─── Mobile overflow fixes ─── */
#article a {
  word-break: break-all;
}

#article code {
  word-break: break-all;
}

@media (max-width: 900px) {
  table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
}