/* Reserve — "switchgear ledger": engineering paper, ink, arc-amber. System fonts only. */
:root {
  --paper: #f2ede1;
  --paper-2: #e9e2d1;
  --card: #f8f5ec;
  --ink: #18222e;
  --ink-2: #2c3a4a;
  --muted: #5d6673;
  --grid: #ddd5c2;
  --rule: #c9bfa8;
  --amber: #d0661c;
  --amber-ink: #9a4710;
  --t1: #2f7a72;
  --t2: #c9822b;
  --t3: #7a4a8c;
  --t4: #b0412e;
  --accent: var(--amber);
  --serif: "Iowan Old Style", "Charter", "Bitstream Charter", "Sitka Text", Cambria, Georgia, serif;
  --sans: system-ui, -apple-system, "Segoe UI", "Noto Sans", Ubuntu, Cantarell, sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", Menlo, Consolas, "Liberation Mono", monospace;
}
.tier-1 { --accent: var(--t1); } .tier-2 { --accent: var(--t2); } .tier-3 { --accent: var(--t3); } .tier-4 { --accent: var(--t4); }
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; color: var(--ink); font: 17px/1.62 var(--sans);
  background-color: var(--paper);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 32px 32px; background-attachment: fixed;
}
.wrap { max-width: 1180px; margin: 0 auto; padding: 0 22px; }
a { color: var(--ink-2); text-decoration-color: var(--accent); text-decoration-thickness: 2px; text-underline-offset: 3px; transition: color .15s, background-color .15s; }
a:hover { color: var(--amber-ink); background: rgba(208,102,28,.08); }
a:focus-visible, summary:focus-visible, input:focus-visible, select:focus-visible, .tbl-scroll:focus-visible { outline: 3px solid var(--amber); outline-offset: 2px; }
.skip { position: absolute; left: -999px; } .skip:focus { left: 12px; top: 12px; background: var(--ink); color: var(--paper); padding: 8px 12px; z-index: 9; }

/* header */
.site-h { background: var(--ink); color: var(--paper); border-bottom: 4px solid var(--accent); }
.hrow { display: flex; align-items: center; justify-content: space-between; gap: 18px; min-height: 64px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--paper); text-decoration: none; font: 700 22px/1 var(--serif); }
.brand:hover { background: none; color: #fff7e6; }
.brand small { font: 500 12px/1 var(--mono); color: #b9b2a2; letter-spacing: .04em; text-transform: uppercase; }
.mark { color: var(--paper); flex: none; }
.site-h ul { display: flex; flex-wrap: wrap; gap: 2px; list-style: none; margin: 0; padding: 0; }
.site-h nav a { display: block; padding: 8px 12px; color: #e6dfcf; text-decoration: none; font: 600 14px/1 var(--mono); border-bottom: 2px solid transparent; }
.site-h nav a:hover { background: rgba(255,255,255,.08); color: #fff; border-bottom-color: var(--amber); }
.site-h nav a[aria-current="page"] { color: #fff; border-bottom-color: var(--accent); }

/* hero */
.hero { padding: 56px 0 28px; border-bottom: 2px solid var(--ink); margin-bottom: 28px; }
.kicker { font: 700 13px/1 var(--mono); letter-spacing: .14em; text-transform: uppercase; color: var(--accent); margin: 0 0 14px; }
.kicker::before { content: ""; display: inline-block; width: 28px; height: 3px; background: var(--accent); vertical-align: middle; margin-right: 10px; }
h1 { font: 700 clamp(34px, 5.4vw, 64px)/1.04 var(--serif); letter-spacing: -.02em; margin: 0 0 18px; max-width: 18ch; }
.lede { font: 400 20px/1.55 var(--serif); max-width: 62ch; color: var(--ink-2); margin: 0 0 18px; }
.legend { font-size: 14px; color: var(--muted); }
h2 { font: 700 clamp(24px, 3vw, 32px)/1.2 var(--serif); margin: 52px 0 14px; letter-spacing: -.01em; }
h2::before { content: ""; display: block; width: 44px; height: 4px; background: var(--accent); margin-bottom: 14px; }
h3 { font: 700 19px/1.3 var(--sans); margin: 30px 0 8px; color: var(--ink); }
p, ul, ol { max-width: 76ch; }
.lead-p { font-size: 18px; }
section { scroll-margin-top: 12px; }

/* tier nav */
.tiernav ol { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; border: 2px solid var(--ink); background: var(--card); max-width: none; }
.tn { display: grid; gap: 4px; padding: 16px 18px; text-decoration: none; border-right: 1px solid var(--rule); border-top: 6px solid var(--c); height: 100%; transition: background-color .15s, transform .15s; }
.tiernav li:last-child .tn { border-right: 0; }
.tn.t1 { --c: var(--t1); } .tn.t2 { --c: var(--t2); } .tn.t3 { --c: var(--t3); } .tn.t4 { --c: var(--t4); }
.tn:hover { background: var(--paper-2); color: var(--ink); }
.tn:hover .tn-n { color: var(--c); }
.tn.is-cur { background: var(--ink); color: var(--paper); }
.tn.is-cur .tn-k, .tn.is-cur .tn-n { color: #d8d0bd; }
.tn-n { font: 700 12px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.tn-l { font: 700 17px/1.25 var(--serif); }
.tn-k { font: 600 13px/1 var(--mono); color: var(--muted); }

/* tables */
.tbl { margin: 22px 0 8px; }
.tbl-scroll { overflow-x: auto; border: 2px solid var(--ink); background: var(--card); }
table { border-collapse: collapse; width: 100%; font-size: 15px; min-width: 720px; }
caption { caption-side: top; text-align: left; font: 700 13px/1.3 var(--mono); letter-spacing: .06em; text-transform: uppercase; padding: 12px 14px; background: var(--ink); color: var(--paper); }
thead th { background: var(--paper-2); font: 700 13px/1.3 var(--mono); text-align: left; vertical-align: bottom; padding: 10px 12px; border-bottom: 2px solid var(--ink); }
thead th a { color: inherit; }
tbody th { text-align: left; font-weight: 700; background: rgba(233,226,209,.55); }
td, tbody th { padding: 10px 12px; border-top: 1px solid var(--rule); vertical-align: top; }
td + td, th + td { border-left: 1px dashed var(--rule); }
tbody tr { transition: background-color .12s; }
tbody tr:hover { background: #fff7e3; }
tbody tr:hover > th { box-shadow: inset 4px 0 0 var(--accent); }
figcaption { font-size: 13.5px; color: var(--muted); margin-top: 8px; max-width: 90ch; }
.matrix thead th:nth-child(2) { border-top: 6px solid var(--t1); }
.matrix thead th:nth-child(3) { border-top: 6px solid var(--t2); }
.matrix thead th:nth-child(4) { border-top: 6px solid var(--t3); }
.matrix thead th:nth-child(5) { border-top: 6px solid var(--t4); }
.matrix table { min-width: 980px; }
.matrix tbody th { width: 15%; }

.tag { display: inline-block; font: 700 10.5px/1 var(--mono); letter-spacing: .05em; text-transform: uppercase; padding: 3px 5px; border: 1px solid; border-radius: 2px; vertical-align: 2px; white-space: nowrap; }
.tag-ms { color: #1f5f58; border-color: #1f5f58; background: #e1efe9; }
.tag-calc { color: #2c3a4a; border-color: #2c3a4a; background: #e3e7ee; }
.tag-est { color: #8a4b0f; border-color: #c48a45; background: #f8e9d2; }
.tag-pend { color: #8f2f22; border-color: #b0412e; background: #f6e0da; }
a.src { font-size: 14px; }
a.src::before { content: "Source: "; color: var(--muted); }

.formula { font: 14.5px/1.6 var(--mono); background: var(--card); border-left: 4px solid var(--accent); padding: 10px 14px; display: block; max-width: 90ch; }

/* diagrams & trees */
.diagram { margin: 24px 0; background: var(--card); border: 1px solid var(--rule); padding: 14px; }
.diagram svg { display: block; width: 100%; max-width: 720px; height: auto; font-family: var(--mono); }
.tree { margin: 16px 0; }
.tree pre { margin: 0; font: 13.5px/1.6 var(--mono); background: var(--ink); color: #ece5d5; padding: 16px 18px; overflow-x: auto; border-left: 6px solid var(--accent); white-space: pre; }
.tree figcaption { margin: 0 0 6px; font: 700 12px/1.3 var(--mono); text-transform: uppercase; letter-spacing: .06em; color: var(--ink-2); }

/* callouts */
.callout { border: 2px solid var(--ink); background: var(--card); padding: 14px 18px; margin: 20px 0; max-width: 82ch; }
.callout-warn { border-left: 10px solid var(--amber); }
.callout-danger { border-left: 10px solid var(--t4); background: #f7e8e1; }
.callout-t { font: 700 12px/1 var(--mono); letter-spacing: .12em; text-transform: uppercase; margin: 0 0 8px; }
.callout p:last-child { margin-bottom: 0; }

.two { display: grid; grid-template-columns: 1fr 1fr; gap: 0 44px; }
.rules { counter-reset: r; list-style: none; padding: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 14px; max-width: none; }
.rules li { counter-increment: r; background: var(--card); border: 1px solid var(--rule); border-top: 4px solid var(--ink); padding: 16px 18px 16px 58px; position: relative; transition: border-top-color .15s; }
.rules li:hover { border-top-color: var(--amber); }
.rules li::before { content: counter(r, decimal-leading-zero); position: absolute; left: 16px; top: 14px; font: 700 20px/1 var(--mono); color: var(--amber); }
.checklist { list-style: none; padding: 0; }
.checklist li { padding: 8px 0 8px 32px; position: relative; border-bottom: 1px dashed var(--rule); }
.checklist li::before { content: ""; position: absolute; left: 4px; top: 13px; width: 14px; height: 14px; border: 2px solid var(--accent); }
.steps li { margin-bottom: 6px; }

/* estimator */
.calc { margin: 28px 0; border: 2px solid var(--ink); background: var(--card); padding: 4px 22px 16px; border-top: 8px solid var(--t1); }
.calc-f { display: grid; grid-template-columns: repeat(3, 1fr) 1.3fr; gap: 14px; align-items: end; }
.calc label { display: grid; gap: 6px; font: 700 12.5px/1.2 var(--mono); text-transform: uppercase; letter-spacing: .04em; }
.calc input, .calc select { font: 16px/1 var(--mono); padding: 10px; border: 2px solid var(--ink); background: var(--paper); color: var(--ink); width: 100%; height: 44px; border-radius: 0; }
.calc input:hover, .calc select:hover { border-color: var(--t1); }
.calc output { display: flex; align-items: center; height: 44px; padding: 0 12px; background: var(--ink); color: #f5d9b8; font: 700 16px/1 var(--mono); }
.small { font-size: 13.5px; color: var(--muted); }

/* faq */
.faq details { border-top: 1px solid var(--ink); max-width: 82ch; }
.faq details:last-child { border-bottom: 1px solid var(--ink); }
.faq summary { cursor: pointer; padding: 16px 32px 16px 0; font: 700 18px/1.35 var(--serif); list-style: none; position: relative; transition: color .15s; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; position: absolute; right: 4px; top: 14px; font: 700 22px/1 var(--mono); color: var(--accent); }
.faq details[open] summary::after { content: "\2212"; }
.faq summary:hover { color: var(--amber-ink); }
.faq details p { margin: 0 0 18px; }
.sources ul { font-size: 15px; }

/* footer */
.site-f { margin-top: 72px; background: var(--ink); color: #d6cfbf; border-top: 4px solid var(--accent); padding: 36px 0; font-size: 14.5px; }
.frow { display: grid; grid-template-columns: 2fr 1fr; gap: 32px; }
.brand-f { font: 700 22px/1 var(--serif); color: var(--paper); margin: 0 0 10px; }
.site-f ul { list-style: none; padding: 0; margin: 0; }
.site-f a { color: #efe8d8; display: inline-block; padding: 4px 0; }
.site-f a:hover { color: #fff; background: none; text-decoration-color: var(--amber); }

@media (max-width: 860px) {
  .tiernav ol, .rules { grid-template-columns: 1fr 1fr; }
  .tiernav li:nth-child(2) .tn { border-right: 0; }
  .two, .frow { grid-template-columns: 1fr; }
  .calc-f { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 560px) {
  body { font-size: 16px; }
  .tiernav ol, .rules, .calc-f { grid-template-columns: 1fr; }
  .tn { border-right: 0; }
  .brand small { display: none; }
  .hero { padding-top: 36px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }
@media print { body { background: none; } .site-h nav, .tiernav { display: none; } }