:root {
  --bg: #fafafa;
  --panel: #ffffff;
  --text: #1a1a1a;
  --muted: #5a5a5a;
  --faint: #9a9a9a;
  --accent: #0b7a55;
  --accent-soft: #e6f4ed;
  --border: #e2e2e2;
  --ink: #12312a;
}
* { 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 #0b201b;
}
header.site-header .nav-inner {
  max-width: 1020px; 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; }

.nav-dropdown { position: relative; }
.nav-dropdown > a::after { content: ' \25BE'; font-size: 0.75em; opacity: 0.8; }
.nav-dropdown-menu {
  display: none; position: absolute; top: 100%; left: 0; z-index: 20;
  background: var(--ink); border: 1px solid rgba(255,255,255,0.12);
  border-radius: 8px; padding: 6px; margin-top: 8px;
  min-width: 260px; box-shadow: 0 8px 24px rgba(0,0,0,0.25);
}
.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu { display: block; }
.nav-dropdown-menu a {
  display: block; padding: 7px 10px; border-radius: 5px;
  font-size: 0.88rem; opacity: 0.9; white-space: nowrap;
}
.nav-dropdown-menu a:hover { opacity: 1; background: rgba(255,255,255,0.08); text-decoration: none; }

main { max-width: 1020px; 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;
}

/* diagrams */
.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;
}

/* dictionary table */
.table-wrap { overflow-x: auto; margin: 18px 0; }
table.dict { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
table.dict th, table.dict td {
  text-align: left; padding: 11px 14px;
  border-bottom: 1px solid var(--border); vertical-align: top;
}
table.dict 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.dict tbody td:first-child { font-weight: 600; white-space: nowrap; }
table.dict tr:last-child td { border-bottom: none; }

/* 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;
}

/* demo controls */
.demo-panel {
  background: var(--panel); border: 1px solid var(--border);
  border-radius: 10px; padding: 18px 20px; margin: 20px auto;
  max-width: 840px;
}
.demo-panel canvas { width: 100%; height: auto; display: block; border-radius: 6px; }
.controls {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 10px 28px; margin-top: 14px; font-size: 0.9rem;
}
.controls label {
  display: grid; grid-template-columns: 148px 1fr 52px;
  align-items: center; gap: 10px; color: var(--muted); overflow: hidden;
}
.controls label .lab { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.controls input[type=range] { width: 100%; min-width: 0; accent-color: var(--accent); }
.controls .val {
  text-align: right; font-variant-numeric: tabular-nums;
  color: var(--text); font-family: "SFMono-Regular", Menlo, Consolas, monospace; font-size: 0.85rem;
}
.controls button {
  padding: 6px 16px; border: 1px solid var(--border); border-radius: 6px;
  background: var(--panel); color: var(--ink); font-size: 0.9rem; cursor: pointer;
}
.controls button:hover { border-color: var(--accent); color: var(--accent); }
.readout {
  display: flex; flex-wrap: wrap; gap: 8px 28px; margin-top: 12px;
  font-size: 0.92rem; color: var(--muted);
}
.readout b { color: var(--ink); font-variant-numeric: tabular-nums; }

footer {
  max-width: 1020px; margin: 40px auto 24px; padding: 16px 24px;
  font-size: 0.85rem; color: var(--muted); border-top: 1px solid var(--border);
}