:root {
  --bg: #fafafa;
  --panel: #ffffff;
  --text: #1a1a1a;
  --muted: #5a5a5a;
  --faint: #9a9a9a;
  --accent: #4a3aff;
  --accent-soft: #ecebfb;
  --border: #e2e2e2;
  --ink: #1f1d3d;
}
* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  background: var(--bg); color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6; font-size: 17px;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

header.site-header {
  background: var(--ink); color: #fff;
  padding: 14px 24px; border-bottom: 1px solid #15132a;
}
header.site-header .nav-inner {
  max-width: 860px; margin: 0 auto;
  display: flex; gap: 18px; align-items: center; flex-wrap: wrap;
}
header.site-header .brand { font-weight: 600; font-size: 1.1rem; color: #fff; }
header.site-header nav { display: flex; flex-wrap: wrap; gap: 0 18px; }
header.site-header nav a { color: #fff; opacity: 0.85; font-size: 0.95rem; }
header.site-header nav a:hover { opacity: 1; }

main { max-width: 860px; margin: 32px auto; padding: 0 24px 60px; }
h1 { font-size: 2.1rem; margin: 0 0 4px; line-height: 1.2; }
.subtitle { color: var(--muted); font-size: 1.12rem; margin: 0 0 24px; }
h2 {
  font-size: 1.3rem; margin: 2.2em 0 0.6em;
  border-bottom: 1px solid var(--border); padding-bottom: 4px;
}
p { margin: 0.8em 0; }
.lead { font-size: 1.07rem; }
ul { padding-left: 1.3em; }
li { margin-bottom: 8px; }
.muted { color: var(--muted); }
code {
  background: #f3f3f7; padding: 1px 5px;
  border-radius: 3px; font-size: 0.92em;
  font-family: "SFMono-Regular", Menlo, Consolas, monospace;
}
blockquote {
  margin: 18px 0; padding: 10px 18px;
  border-left: 3px solid #ddd; color: var(--muted);
}
.equation-card {
  background: var(--panel); border: 1px solid var(--border);
  border-radius: 8px; padding: 14px 18px; margin: 18px 0;
  text-align: center; overflow-x: auto;
}

/* two-worlds diagram */
.diagram { margin: 26px 0 10px; }
.diagram svg { width: 100%; height: auto; display: block; }
.diagram .caption {
  text-align: center; color: var(--muted);
  font-size: 0.9rem; margin: 6px 0 0;
}

/* implementations table */
.table-wrap { overflow-x: auto; margin: 18px 0; }
table.impl { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
table.impl th, table.impl td {
  text-align: left; padding: 11px 14px;
  border-bottom: 1px solid var(--border); vertical-align: top;
}
table.impl thead th {
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.04em;
  color: var(--muted); font-weight: 600; border-bottom: 2px solid var(--border);
}
table.impl tbody td:first-child { font-weight: 600; white-space: nowrap; }
table.impl tr:last-child td { border-bottom: none; }
table.impl .mode { color: var(--muted); font-size: 0.9rem; }

/* bibliography */
.bib h3 { font-size: 1.02rem; margin-top: 1.4em; color: var(--ink); }
.bib ul { list-style: none; padding-left: 0; }
.bib li { margin-bottom: 12px; padding-left: 1.2em; text-indent: -1.2em; }

.pagenav { margin: 0 0 22px; font-size: 0.95rem; }
.next-steps {
  background: var(--accent-soft); border-radius: 8px;
  padding: 4px 20px; margin: 24px 0;
}

footer {
  max-width: 860px; margin: 40px auto 24px; padding: 16px 24px;
  font-size: 0.85rem; color: var(--muted); border-top: 1px solid var(--border);
}