:root {
  --bg: #ffffff;
  --surface: #f6f7f9;
  --text: #1f2328;
  --muted: #59636e;
  --border: #d8dee4;
  --accent: #990000;          /* USC cardinal */
  --accent-soft: #fbeaea;
  --link: #0b5cad;
  --hero-bg: #990000;
  --hero-text: #ffffff;
  --code-bg: #f3f4f6;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115;
    --surface: #171a21;
    --text: #e6e8eb;
    --muted: #9aa4af;
    --border: #2c323c;
    --accent: #ff8080;
    --accent-soft: #3a1c1c;
    --link: #6cb6ff;
    --hero-bg: #5c0d0d;
    --hero-text: #ffffff;
    --code-bg: #1b1f27;
  }
}

* { box-sizing: border-box; }
html { scroll-padding-top: 4rem; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Lato", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
}
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 0 16px; }

/* Navigation */
.site-nav {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; gap: 1.5rem;
  padding: 0.6rem max(16px, calc((100% - 1180px) / 2 + 16px));
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; color: var(--accent); font-size: 1.1rem; }
.nav-links { display: flex; align-items: center; gap: 1.25rem; margin-left: auto; }
.nav-links > a, .dd > summary { color: var(--text); cursor: pointer; padding: 0.25rem 0; }
.nav-links > a[aria-current="page"], .dd[data-active] > summary { color: var(--accent); font-weight: 700; }
.dd { position: relative; }
.dd > summary { list-style: none; }
.dd > summary::-webkit-details-marker { display: none; }
.dd > summary::after { content: " ▾"; font-size: 0.8em; }
.dd-menu {
  position: absolute; right: 0; top: 2.2rem;
  display: flex; gap: 2rem;
  padding: 1rem 1.25rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
  white-space: nowrap;
}
.dd-group > span { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); }
.dd-group ul { list-style: none; margin: 0.4rem 0 0; padding: 0; }
.dd-group li { margin: 0.2rem 0; }
.dd-group a { color: var(--text); }
.dd-group a[aria-current="page"] { color: var(--accent); font-weight: 700; }
.nav-toggle { display: none; margin-left: auto; font-size: 1.4rem; cursor: pointer; }

/* Headers */
.hero { background: var(--hero-bg); color: var(--hero-text); padding: 3.5rem 0 3rem; }
.hero h1 { margin: 0; font-size: clamp(2rem, 5vw, 3rem); }
.hero .tagline { margin: 0.5rem 0 0; font-size: 1.2rem; opacity: 0.9; }
.page-head { background: var(--surface); border-bottom: 1px solid var(--border); padding: 2.2rem 0 1.6rem; }
.page-head h1 { margin: 0; font-size: clamp(1.7rem, 4vw, 2.4rem); }

/* Content */
.content { padding-top: 1rem; padding-bottom: 3rem; }
.content h2 { margin: 2.2rem 0 0.6rem; padding-bottom: 0.3rem; border-bottom: 2px solid var(--accent-soft); font-size: 1.55rem; }
.content h3 { margin: 1.6rem 0 0.4rem; font-size: 1.2rem; }
.content p { margin: 0.6rem 0; }
.embed { margin: 0.8rem 0; }
.embed h2 { font-size: 1.25rem; border-bottom: none; margin-top: 1.6rem; }
mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; }

/* Tables */
.table-wrap { overflow-x: auto; margin: 0.8rem 0 1.2rem; border: 1px solid var(--border); border-radius: 8px; }
table { border-collapse: collapse; width: 100%; font-size: 0.9rem; }
th, td { padding: 0.45rem 0.7rem; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
th { background: var(--surface); font-weight: 700; white-space: nowrap; position: sticky; top: 0; }
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: var(--surface); }
td:first-child a { font-weight: 700; }
/* Domain-grouped tables (home page): one merged domain cell, a strong rule between domains */
tr.domain-start > td { border-top: 2px solid var(--border); }
tbody tr.domain-start:first-child > td { border-top: none; }
td.domain { background: var(--surface); vertical-align: middle; border-right: 1px solid var(--border); }
td.domain a { font-weight: 700; }
tbody tr:hover > td.domain { background: var(--surface); }
/* Collapsible formulations */
details.formulation { border: 1px solid var(--border); border-radius: 8px; margin: 0.8rem 0; padding: 0 1rem; }
details.formulation > summary { cursor: pointer; padding: 0.6rem 0; font-weight: 700; }
details.formulation[open] > summary { border-bottom: 1px solid var(--border); margin-bottom: 0.4rem; }

/* Reference lists */
.ref { padding-left: 1.5rem; text-indent: -1.5rem; margin: 0.45rem 0; }
.ref-key { font-weight: 700; }

/* BibTeX */
pre {
  position: relative;
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem 1rem;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.45;
}
.copy-btn {
  position: absolute; top: 0.5rem; right: 0.5rem;
  font: inherit; font-size: 0.75rem;
  padding: 0.2rem 0.6rem;
  color: var(--muted); background: var(--bg);
  border: 1px solid var(--border); border-radius: 6px; cursor: pointer;
}
.copy-btn:hover { color: var(--text); }

.site-footer { border-top: 1px solid var(--border); padding: 1.5rem 0; color: var(--muted); font-size: 0.9rem; }

@media (max-width: 760px) {
  .site-nav { flex-wrap: wrap; gap: 0.5rem; }
  .nav-toggle { display: block; }
  .nav-links { display: none; width: 100%; flex-direction: column; align-items: flex-start; gap: 0.4rem; padding: 0.5rem 0; }
  #nav-toggle:checked ~ .nav-links { display: flex; }
  .dd-menu { position: static; flex-direction: column; gap: 0.8rem; box-shadow: none; border: none; padding: 0.4rem 0 0 0.8rem; white-space: normal; }
  .hero { padding: 2.2rem 0 2rem; }
}