:root {
  --fg: #1c2430;
  --muted: #5b6675;
  --bg: #f7f8fa;
  --surface: #ffffff;
  --accent: #2f6fed;
  --accent-strong: #1d4ed8;
  --border: #e4e7ec;
  --code-bg: #f0f2f5;
  --warn-bg: #fff8e1;
  --warn-border: #f0c000;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.04);
  --shadow-md: 0 4px 12px rgba(16, 24, 40, 0.08), 0 2px 4px rgba(16, 24, 40, 0.04);
  --max-width: 820px;
  --row1-h: 54px;
  --row2-h: 44px;
  --header-h: var(--row1-h);
}
/* Pages in a nav group render a second top-bar row, so sticky table headers
   must clear both rows. */
.page-repricing, .page-fracgas, .page-runtime, .page-glue,
.page-methodology, .page-reference { --header-h: calc(var(--row1-h) + var(--row2-h)); }

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16.5px;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Header / nav: a sticky two-tier top bar (primary sections + per-group sub-pages) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
}
.topbar-primary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem 2rem;
  min-height: var(--row1-h);
  padding: 0.4rem 1.5rem;
}
.topbar-secondary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
  min-height: var(--row2-h);
  padding: 0.3rem 1.5rem;
  border-top: 1px solid var(--border);
  background: rgba(16, 24, 40, 0.025);
}
.site-title {
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
}
.site-nav { display: flex; flex-wrap: wrap; gap: 1.25rem; }
.site-nav a, .topbar-secondary a {
  color: var(--muted);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.site-nav a:hover, .topbar-secondary a:hover { color: var(--accent); }
.site-nav a.active, .topbar-secondary a.active { color: var(--fg); font-weight: 600; border-bottom-color: var(--accent); }
.topbar-secondary a { font-size: 0.95rem; }

/* Content */
.content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
}
.content h1 {
  font-size: 2rem;
  letter-spacing: -0.02em;
  margin-top: 0;
  margin-bottom: 1rem;
}
.content h2 {
  font-size: 1.35rem;
  letter-spacing: -0.01em;
  margin-top: 2.75rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.35rem;
}
.content h3 { font-size: 1.1rem; }
.content a { color: var(--accent); text-decoration-color: rgba(47, 111, 237, 0.35); text-underline-offset: 2px; }
.content a:hover { color: var(--accent-strong); text-decoration-color: currentColor; }

/* Takeaway callout */
.takeaway {
  background: linear-gradient(0deg, rgba(47, 111, 237, 0.05), rgba(47, 111, 237, 0.05)), var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-sm);
}
.takeaway > :first-child { margin-top: 0; }
.takeaway > :last-child { margin-bottom: 0; }
.takeaway ol, .takeaway ul { padding-left: 1.25rem; }
.takeaway li + li { margin-top: 0.4rem; }

/* Tables */
table {
  border-collapse: separate;
  border-spacing: 0;
  width: 100%;
  margin: 1.5rem 0;
  font-size: 0.92rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
}
th, td { border-bottom: 1px solid var(--border); padding: 0.5rem 0.7rem; text-align: right; }
tr:last-child td { border-bottom: none; }
th {
  background: var(--code-bg);
  position: sticky;
  top: var(--header-h);
  z-index: 2;
  font-weight: 600;
  white-space: nowrap;
  box-shadow: inset 0 -1px 0 var(--border);
}
/* Round outer corners without overflow:hidden (which would break sticky th) */
thead tr:first-child th:first-child { border-top-left-radius: 8px; }
thead tr:first-child th:last-child { border-top-right-radius: 8px; }
tbody tr:last-child td:first-child { border-bottom-left-radius: 8px; }
tbody tr:last-child td:last-child { border-bottom-right-radius: 8px; }
tbody tr { transition: background 0.1s ease; }
tbody tr:nth-child(even) { background: rgba(16, 24, 40, 0.018); }
tbody tr:hover { background: rgba(47, 111, 237, 0.06); }
td:first-child, th:first-child { text-align: left; }
.worst-case { background: #fdecea; font-weight: 600; }
tbody tr:hover .worst-case { background: #fbdcd6; }

/* Code / preformatted fit summaries */
code {
  background: var(--code-bg);
  padding: 0.12em 0.35em;
  border-radius: 4px;
  font-size: 0.85em;
}
pre {
  background: var(--code-bg);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.82rem;
  line-height: 1.5;
}
pre code { background: none; padding: 0; }

/* Figures */
/* Bare markdown images (e.g. the new-gas heatmap/provenance plots) aren't wrapped
   in <figure>, so cap every content image to the column width. */
.content img { max-width: 100%; height: auto; }
figure { margin: 1.75rem 0; text-align: center; }
figure img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
}
figcaption { color: var(--muted); font-size: 0.85rem; margin-top: 0.5rem; }

/* Cards (landing page) */
.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; margin: 2rem 0; }
@media (max-width: 640px) { .cards { grid-template-columns: 1fr; } }

/* Plot grid (fit/glue pages): 2 plots per row; a lone trailing plot spans both columns */
.plot-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; margin: 2rem 0; }
.plot-grid > figure:last-child:nth-child(odd) { grid-column: 1 / -1; }
@media (max-width: 640px) { .plot-grid { grid-template-columns: 1fr; } }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.4rem;
  text-decoration: none;
  color: var(--fg);
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.card h3 { margin: 0 0 0.5rem; color: var(--accent); }
.card p { margin: 0; color: var(--muted); font-size: 0.9rem; }

/* Warnings */
.warning {
  background: var(--warn-bg);
  border: 1px solid var(--warn-border);
  border-left: 4px solid var(--warn-border);
  border-radius: 8px;
  padding: 0.85rem 1.1rem;
  margin: 1.25rem 0;
}

/* Filter controls (runtime / glue pages) */
.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  margin: 1.5rem 0;
  padding: 1rem 1.25rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: var(--shadow-sm);
}
.filters label { font-size: 0.9rem; font-weight: 600; }
.filters select {
  padding: 0.4rem 0.6rem;
  font-size: 0.9rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--surface);
  color: var(--fg);
}
.fit-section { margin: 2rem 0; padding-top: 1.25rem; border-top: 1px solid var(--border); }
.fit-section h3 { margin-top: 0; }
.stat-grid { display: flex; flex-wrap: wrap; gap: 1.5rem; margin: 0.75rem 0; font-size: 0.9rem; }
.stat-grid .stat { color: var(--muted); }
.stat-grid .stat strong { color: var(--fg); }

/* Repricing, bottleneck & reference pages: a wider canvas for the table */
.page-repricing .content, .page-bottleneck .content, .page-reference .content { max-width: 1100px; }
.filters .checkbox { display: inline-flex; align-items: center; gap: 0.4rem; font-weight: 600; }
p.muted { color: var(--muted); font-size: 0.9rem; margin-top: -0.5rem; }

/* Mobile: top bar stays sticky; rows wrap and the title sits above the nav */
@media (max-width: 720px) {
  .topbar-primary { align-items: baseline; gap: 0.5rem 1.25rem; }
  .site-nav { gap: 0.75rem 1rem; }
}

/* Plotly charts (throughput-loss page) */
.plotly-chart { width: 100%; min-height: 340px; margin: 1.5rem 0; }

/* Throughput-loss headline (scenario × metric) table */
#fracgas-headline { max-width: 640px; font-variant-numeric: tabular-nums; }
#fracgas-headline th small { font-weight: 400; color: var(--muted); }
#fracgas-headline tbody th { text-align: left; font-weight: 600; }
#fracgas-headline tr.ideal td, #fracgas-headline tr.ideal th { color: var(--muted); }
.note { color: var(--muted); font-size: 0.9rem; border-left: 3px solid var(--border); padding-left: 0.8rem; }
.note a { white-space: nowrap; }

/* Bottleneck table */
#bottleneck-table { font-variant-numeric: tabular-nums; }
#bottleneck-table td.worst { font-weight: 600; }
#bottleneck-table td.flag { text-align: center; color: #b42318; }
#bottleneck-table th[data-sort] { cursor: pointer; user-select: none; }

/* Reference table: left-align every column, allow code to wrap */
#reference-table th, #reference-table td { text-align: left; }
#reference-table th[data-sort] { cursor: pointer; user-select: none; }
#reference-table td code { white-space: normal; word-break: break-word; }
.muted-inline { color: var(--muted); font-size: 0.8em; }

/* Anchor control panel */
.anchor-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 10px;
  padding: 1.1rem 1.25rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-sm);
}
.anchor-control { display: flex; flex-wrap: wrap; align-items: center; gap: 0.75rem 1.25rem; }
.anchor-inputs { display: flex; align-items: center; gap: 0.75rem; flex: 1 1 320px; }
.anchor-inputs input[type="range"] { flex: 1 1 auto; min-width: 160px; accent-color: var(--accent); }
.anchor-inputs input[type="number"] {
  width: 7rem;
  padding: 0.4rem 0.6rem;
  font-size: 1rem;
  font-variant-numeric: tabular-nums;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--surface);
  color: var(--fg);
}
.anchor-unit { color: var(--muted); font-size: 0.9rem; }
.anchor-summary { font-size: 1.02rem; }

/* Live table cells */
#repricing-table { font-variant-numeric: tabular-nums; }
#repricing-table td.proposed { font-weight: 600; }
#repricing-table td.diff.up,
#repricing-table td.pct.up,
#repricing-table td.flag.up { color: #b42318; }
#repricing-table td.diff.down,
#repricing-table td.pct.down,
#repricing-table td.flag.down { color: #067647; }
#repricing-table td.flag { text-align: center; font-weight: 700; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); padding: 1.5rem; color: var(--muted); font-size: 0.8rem; }
.site-footer .repro { max-width: var(--max-width); margin: 0 auto; }
.site-footer code { font-size: 0.95em; }

/* Dark mode */
@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e6e9ef;
    --muted: #9aa4b2;
    --bg: #0f1218;
    --surface: #181c24;
    --accent: #6ea0ff;
    --accent-strong: #93b8ff;
    --border: #2a313d;
    --code-bg: #1f2530;
    --warn-bg: #2e2a16;
    --warn-border: #b89400;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.5);
  }
  .site-header { background: rgba(15, 18, 24, 0.78); }
  .content a { text-decoration-color: rgba(110, 160, 255, 0.4); }
  tbody tr:nth-child(even) { background: rgba(255, 255, 255, 0.025); }
  tbody tr:hover { background: rgba(110, 160, 255, 0.1); }
  .worst-case { background: #4a2420; color: #ffd9d2; }
  tbody tr:hover .worst-case { background: #5a2c27; }
  figure img { filter: brightness(0.92); }
  #repricing-table td.diff.up,
  #repricing-table td.pct.up,
  #repricing-table td.flag.up { color: #ff9b8e; }
  #repricing-table td.diff.down,
  #repricing-table td.pct.down,
  #repricing-table td.flag.down { color: #5fd4a0; }
}