/* BuildersCalcs site.css
   Mobile-first (360px base). Implements design/DESIGN.md.
   Section 0 is a copy of design/tokens/tokens.css (source of truth); keep them in sync. */

/* ---------- 0. Tokens ---------- */
:root {
  color-scheme: light dark;
  --c-paper: #f5f4ee;
  --c-panel: #fcfbf7;
  --c-ink: #17202a;
  --c-ink-2: #34404c;
  --c-muted: #56606a;
  --c-line: #d9d6cb;
  --c-line-strong: #7d848a;
  --c-accent: #1b57a6;
  --c-accent-ink: #fcfbf7;
  --c-accent-soft: #e1e9f4;
  --c-ok: #2d6a36;
  --c-warn: #8a5300;
  --c-stop: #b0261b;
  --c-focus: #1b57a6;
  --f-head: "Sofia Sans Condensed", "Arial Narrow", "Roboto Condensed", "Helvetica Neue", sans-serif;
  --f-body: "Public Sans", -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --f-num: "Public Sans", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --t-xs: 0.8125rem;
  --t-sm: 0.875rem;
  --t-base: 1.0625rem;
  --t-md: 1.25rem;
  --t-lg: 1.5rem;
  --t-xl: 1.875rem;
  --t-2xl: clamp(2rem, 1.6rem + 2vw, 2.75rem);
  --t-3xl: clamp(2.5rem, 1.9rem + 3vw, 3.75rem);
  --lh-tight: 1.08;
  --lh-body: 1.58;
  --s-1: 0.25rem;
  --s-2: 0.5rem;
  --s-3: 0.75rem;
  --s-4: 1rem;
  --s-5: 1.5rem;
  --s-6: 2rem;
  --s-7: 3rem;
  --s-8: 4rem;
  --s-9: 6rem;
  --s-10: 8rem;
  --r-1: 2px;
  --r-2: 4px;
  --e-1: 0 1px 0 rgba(23, 32, 42, 0.06), 0 2px 6px -2px rgba(23, 32, 42, 0.14);
  --w-text: 68ch;
  --w-page: 72rem;
  --m-fast: 140ms;
  --m-ease: cubic-bezier(0.2, 0.7, 0.2, 1);
}
@media (prefers-color-scheme: dark) {
  :root {
    --c-paper: #12161b;
    --c-panel: #1a2028;
    --c-ink: #ebe9e2;
    --c-ink-2: #c8ccd1;
    --c-muted: #9aa3ac;
    --c-line: #2c343d;
    --c-line-strong: #6d7782;
    --c-accent: #86b4ec;
    --c-accent-ink: #0e1620;
    --c-accent-soft: #1c2b3f;
    --c-ok: #82c78a;
    --c-warn: #e5b45a;
    --c-stop: #ff9286;
    --c-focus: #9cc6ff;
    --e-1: 0 1px 0 rgba(0, 0, 0, 0.4), 0 2px 8px -2px rgba(0, 0, 0, 0.5);
  }
}
@media (prefers-reduced-motion: reduce) {
  :root { --m-fast: 0ms; }
}

/* ---------- 1. Fonts ---------- */
@font-face {
  font-family: "Sofia Sans Condensed";
  src: url("/static/fonts/sofia-sans-condensed-var-latin.woff2") format("woff2");
  font-weight: 500 800;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Public Sans";
  src: url("/static/fonts/public-sans-var-latin.woff2") format("woff2");
  font-weight: 400 700;
  font-style: normal;
  font-display: swap;
}

/* ---------- 2. Base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--c-paper);
  color: var(--c-ink);
  font-family: var(--f-body);
  font-size: var(--t-base);
  line-height: var(--lh-body);
  font-feature-settings: "kern", "lnum";
  overflow-wrap: break-word;
}
img, svg, video { max-width: 100%; height: auto; }
h1, h2, h3, h4 {
  font-family: var(--f-head);
  line-height: var(--lh-tight);
  color: var(--c-ink);
  margin: var(--s-7) 0 var(--s-3);
  text-wrap: balance;
}
h1 { font-size: var(--t-3xl); font-weight: 800; letter-spacing: -0.02em; margin-top: 0; }
h2 { font-size: var(--t-2xl); font-weight: 750; letter-spacing: -0.01em; }
h3 { font-size: var(--t-lg); font-weight: 700; margin-top: var(--s-6); }
h4 { font-size: var(--t-md); font-weight: 700; margin-top: var(--s-5); }
p, ul, ol, dl { margin: 0 0 var(--s-4); }
ul, ol { padding-left: 1.25em; }
li + li { margin-top: var(--s-1); }
a {
  color: var(--c-ink);
  text-decoration-line: underline;
  text-decoration-color: var(--c-line-strong);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
  transition: text-decoration-color var(--m-fast) var(--m-ease);
}
a:hover { text-decoration-color: currentColor; text-decoration-thickness: 2px; }
.content a { color: var(--c-accent); text-decoration-color: currentColor; }
strong, b { font-weight: 650; }
small { font-size: var(--t-sm); }
hr {
  border: 0;
  height: 14px;
  margin: var(--s-7) 0;
  background:
    linear-gradient(var(--c-line-strong), var(--c-line-strong)) left bottom / 100% 1px no-repeat,
    repeating-linear-gradient(90deg, var(--c-line-strong) 0 1px, transparent 1px 8px) left bottom / 100% 5px no-repeat;
}
code, kbd, samp {
  font-family: var(--f-num);
  font-variant-numeric: tabular-nums slashed-zero;
  font-size: 0.94em;
  background: var(--c-accent-soft);
  padding: 0 0.25em;
  border-radius: var(--r-1);
}
abbr[title] { text-decoration: underline dotted; cursor: help; }
::selection { background: var(--c-accent); color: var(--c-accent-ink); }
:focus-visible {
  outline: 3px solid var(--c-focus);
  outline-offset: 2px;
  border-radius: var(--r-1);
}
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%);
  white-space: nowrap;
}
.skip-link {
  position: absolute; left: var(--s-2); top: -100px;
  background: var(--c-ink); color: var(--c-paper);
  padding: var(--s-2) var(--s-4); z-index: 10;
}
.skip-link:focus { top: var(--s-2); }

/* Layout shell */
.wrap {
  width: 100%;
  max-width: var(--w-page);
  margin-inline: auto;
  padding-inline: var(--s-4);
}
.layout { display: grid; gap: var(--s-7); padding-block: var(--s-5) var(--s-8); }
.content { min-width: 0; max-width: var(--w-text); }
.content > :first-child { margin-top: 0; }
@media (min-width: 64rem) {
  .wrap { padding-inline: var(--s-6); }
  .layout { grid-template-columns: minmax(0, 1fr) 18rem; column-gap: var(--s-8); }
}

/* Spec-book section numbering inside article content */
.content { counter-reset: sec; }
.content > h2 { counter-increment: sec; }
.content > h2::before {
  content: counter(sec, decimal-leading-zero);
  display: block;
  font-family: var(--f-num);
  font-variant-numeric: tabular-nums;
  font-size: var(--t-xs);
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--c-muted);
  margin-bottom: var(--s-1);
}

/* ---------- 3. Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--s-2);
  min-height: 44px;
  padding: var(--s-2) var(--s-5);
  font: 650 var(--t-base)/1.2 var(--f-body);
  letter-spacing: 0.01em;
  color: var(--c-accent-ink);
  background: var(--c-accent);
  border: 1px solid var(--c-accent);
  border-radius: var(--r-2);
  text-decoration: none;
  cursor: pointer;
  box-shadow: 0 2px 0 color-mix(in srgb, var(--c-accent) 50%, #000);
  transition: transform var(--m-fast) var(--m-ease), box-shadow var(--m-fast) var(--m-ease);
}
.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(2px); box-shadow: none; }
.btn--quiet {
  color: var(--c-ink);
  background: transparent;
  border-color: var(--c-line-strong);
  box-shadow: none;
}
.btn--quiet:hover { border-color: var(--c-ink); }
.btn--quiet:active { transform: translateY(1px); }
.btn[disabled], .btn[aria-disabled="true"] {
  background: var(--c-line); border-color: var(--c-line); color: var(--c-muted);
  box-shadow: none; cursor: not-allowed; transform: none;
}
.btn svg { width: 1.1em; height: 1.1em; }

/* ---------- 4. Header and navigation ---------- */
.site-head {
  border-bottom: 1px solid var(--c-line);
  background: var(--c-paper);
}
.site-head .wrap {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: var(--s-2) var(--s-4);
  min-height: 60px;
  padding-block: var(--s-2);
}
.site-head__logo { display: inline-flex; align-items: center; min-height: 44px; }
.site-head__logo img { display: block; height: 30px; width: auto; }
.site-head__logo .logo-dark { display: none; }
@media (prefers-color-scheme: dark) {
  .site-head__logo .logo-light { display: none; }
  .site-head__logo .logo-dark { display: block; }
}
.nav-toggle {
  display: none;
  min-height: 44px; min-width: 44px;
  padding: 0 var(--s-3);
  font: 600 var(--t-sm)/1 var(--f-body);
  letter-spacing: 0.06em; text-transform: uppercase;
  color: var(--c-ink); background: transparent;
  border: 1px solid var(--c-line-strong); border-radius: var(--r-2);
  cursor: pointer;
}
.nav-toggle__bars { display: inline-block; width: 16px; height: 10px; margin-right: var(--s-2); vertical-align: middle;
  background: linear-gradient(currentColor, currentColor) top / 100% 2px no-repeat,
              linear-gradient(currentColor, currentColor) center / 100% 2px no-repeat,
              linear-gradient(currentColor, currentColor) bottom / 100% 2px no-repeat; }
.nav-main { width: 100%; }
.nav-main ul {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-wrap: wrap; gap: 0 var(--s-1);
}
.nav-main li { margin: 0; }
.nav-main a {
  display: flex; align-items: center;
  min-height: 44px; padding: 0 var(--s-3);
  font: 600 var(--t-sm)/1 var(--f-body);
  letter-spacing: 0.02em;
  text-decoration: none;
  color: var(--c-ink-2);
  border-bottom: 2px solid transparent;
}
.nav-main a:hover { color: var(--c-ink); border-bottom-color: var(--c-line-strong); }
.nav-main a[aria-current="page"], .nav-main a[aria-current="true"] { color: var(--c-ink); border-bottom-color: var(--c-ink); }
/* JS present: collapse on small screens */
.js .nav-toggle { display: inline-flex; align-items: center; }
.js .nav-main { display: none; }
.js .nav-main[data-open] { display: block; }
.js .nav-main[data-open] ul { flex-direction: column; padding-bottom: var(--s-2); }
.js .nav-main[data-open] a { border-bottom: 1px solid var(--c-line); padding-inline: 0; }
@media (min-width: 52rem) {
  .site-head .wrap { flex-wrap: nowrap; }
  .nav-main, .js .nav-main { display: block; width: auto; }
  .js .nav-toggle { display: none; }
  .js .nav-main ul, .nav-main ul { flex-direction: row; }
}

/* ---------- 5. Breadcrumbs, title, lede, byline ---------- */
.crumbs { font-size: var(--t-sm); color: var(--c-muted); margin: var(--s-4) 0 var(--s-3); }
.crumbs ol { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; align-items: center; }
.crumbs li { margin: 0; display: inline-flex; align-items: center; }
.crumbs li + li::before { content: "/"; margin: 0 var(--s-2); color: var(--c-line-strong); }
.crumbs a { color: var(--c-muted); display: inline-flex; align-items: center; min-height: 32px; }
.crumbs a:hover { color: var(--c-ink); }
.crumbs [aria-current="page"] { color: var(--c-ink-2); }

/* Signature 1: the tape rule under every page title */
.page-title { margin-bottom: var(--s-5); }
.page-title h1 { margin: 0 0 var(--s-4); max-width: 22ch; }
.page-title::after {
  content: "";
  display: block;
  height: 16px;
  background:
    /* 16 in. stud-centre marks */
    repeating-linear-gradient(90deg, transparent 0 127px, var(--c-accent) 127px 129px) left bottom / 100% 16px no-repeat,
    /* foot / inch / eighth ticks */
    repeating-linear-gradient(90deg, var(--c-ink) 0 1px, transparent 1px 96px) left bottom / 100% 14px no-repeat,
    repeating-linear-gradient(90deg, var(--c-ink) 0 1px, transparent 1px 8px) left bottom / 100% 8px no-repeat,
    repeating-linear-gradient(90deg, var(--c-line-strong) 0 1px, transparent 1px 4px) left bottom / 100% 4px no-repeat,
    linear-gradient(var(--c-ink), var(--c-ink)) left bottom / 100% 1px no-repeat;
}
.lede {
  font-size: var(--t-md);
  line-height: 1.5;
  color: var(--c-ink-2);
  max-width: 60ch;
  margin: 0 0 var(--s-4);
}
.byline {
  display: flex; flex-wrap: wrap; gap: var(--s-1) var(--s-4);
  font-size: var(--t-sm); color: var(--c-muted);
  margin: 0 0 var(--s-5);
}
.byline time, .byline .byline__checked { font-family: var(--f-num); font-variant-numeric: tabular-nums; }
.byline a { color: var(--c-ink-2); }

/* ---------- 6. Table of contents ---------- */
.toc {
  border-top: 2px solid var(--c-ink);
  padding-top: var(--s-3);
  margin: 0 0 var(--s-6);
  font-size: var(--t-sm);
}
.toc__title {
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted);
  margin: 0 0 var(--s-2);
}
.toc ol { list-style: none; margin: 0; padding: 0; counter-reset: toc; }
.toc li { counter-increment: toc; margin: 0; display: flex; gap: var(--s-3); border-bottom: 1px dotted var(--c-line); }
.toc li::before {
  content: counter(toc, decimal-leading-zero);
  font-family: var(--f-num); font-variant-numeric: tabular-nums;
  color: var(--c-muted); padding-top: 0.6em; min-width: 2ch;
}
.toc a { display: block; flex: 1; padding: 0.55em 0; min-height: 44px; text-decoration: none; color: var(--c-ink-2); }
.toc a:hover { color: var(--c-ink); text-decoration: underline; }

/* ---------- 7. Calculator panel ---------- */
/* Signature 2: grid-paper panel (5 mm minor / 25 mm major feel) */
.calc {
  position: relative;
  margin: 0 0 var(--s-6);
  padding: var(--s-5) var(--s-4) var(--s-4);
  background-color: var(--c-panel);
  background-image:
    linear-gradient(var(--c-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--c-line) 1px, transparent 1px),
    linear-gradient(color-mix(in srgb, var(--c-line) 45%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--c-line) 45%, transparent) 1px, transparent 1px);
  background-size: 80px 80px, 80px 80px, 16px 16px, 16px 16px;
  background-position: -1px -1px;
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-2);
  box-shadow: var(--e-1);
}
.calc__head {
  display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: var(--s-2);
  margin-bottom: var(--s-4);
}
.calc__title {
  font: 750 var(--t-lg)/1.1 var(--f-head);
  margin: 0;
}
.calc__ref {
  font: 600 var(--t-xs)/1 var(--f-num);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted);
}
.calc__fields { display: grid; gap: var(--s-4); margin: 0 0 var(--s-4); border: 0; padding: 0; min-width: 0; }
.calc__fields legend { font-weight: 650; margin-bottom: var(--s-2); padding: 0; }
@media (min-width: 36rem) {
  .calc { padding: var(--s-6) var(--s-6) var(--s-5); }
  .calc__fields { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .calc__fields--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
.calc__actions { display: flex; flex-wrap: wrap; gap: var(--s-3); align-items: center; }

/* Unit toggle (imperial / metric), radio-based segmented control */
.calc-unit-toggle {
  display: inline-flex;
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-2);
  background: var(--c-panel);
  padding: 2px;
  margin: 0;
}
.calc-unit-toggle legend { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }
.calc-unit-toggle input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.calc-unit-toggle label {
  display: inline-flex; align-items: center;
  min-height: 40px; padding: 0 var(--s-4);
  font: 600 var(--t-sm)/1 var(--f-body);
  letter-spacing: 0.02em;
  color: var(--c-ink-2);
  border-radius: var(--r-1);
  cursor: pointer;
}
.calc-unit-toggle input:checked + label { background: var(--c-ink); color: var(--c-paper); }
.calc-unit-toggle input:focus-visible + label { outline: 3px solid var(--c-focus); outline-offset: 1px; }

/* Field */
.calc-field { display: grid; grid-template-columns: minmax(0, 1fr); align-content: start; gap: var(--s-1); min-width: 0; }
.calc-field label, .calc-field__label { font-weight: 600; font-size: var(--t-sm); color: var(--c-ink); }
.calc-field__hint { font-size: var(--t-xs); color: var(--c-muted); }
.calc-field__control {
  display: flex; align-items: stretch;
  background: var(--c-panel);
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-2);
  transition: border-color var(--m-fast) var(--m-ease), box-shadow var(--m-fast) var(--m-ease);
}
.calc-field__control:focus-within { border-color: var(--c-ink); box-shadow: 0 0 0 1px var(--c-ink); }
.calc-field input, .calc-field select {
  flex: 1 1 0%; min-width: 0; width: 100%;
  min-height: 46px;
  padding: 0 var(--s-3);
  font: 500 var(--t-md)/1 var(--f-num);
  font-variant-numeric: tabular-nums lining-nums;
  color: var(--c-ink);
  background: transparent;
  border: 0; border-radius: var(--r-2);
}
.calc-field input:focus, .calc-field select:focus { outline: none; }
.calc-field select { font-family: var(--f-body); font-size: var(--t-base); appearance: auto; }
.calc-field__unit {
  display: flex; align-items: center;
  padding: 0 var(--s-3);
  font: 600 var(--t-sm)/1 var(--f-body);
  color: var(--c-muted);
  border-left: 1px solid var(--c-line);
  white-space: nowrap;
}
/* Invalid state: native :user-invalid plus scripted .is-invalid */
.calc-field__error {
  display: none;
  align-items: flex-start; gap: var(--s-2);
  font-size: var(--t-sm); font-weight: 600;
  color: var(--c-stop);
}
.calc-field__error::before {
  content: "!";
  flex: none;
  display: inline-grid; place-items: center;
  width: 1.25em; height: 1.25em; margin-top: 0.1em;
  font: 800 0.8em/1 var(--f-body);
  color: var(--c-panel); background: var(--c-stop);
  border-radius: 50%;
}
.calc-field.is-invalid .calc-field__control,
.calc-field__control:has(input:user-invalid) {
  border-color: var(--c-stop);
  box-shadow: 0 0 0 1px var(--c-stop);
}
.calc-field.is-invalid .calc-field__error,
.calc-field:has(input:user-invalid) .calc-field__error { display: flex; }

/* Result: Signature 3, the dimension-line result */
.calc-result {
  margin: var(--s-5) 0 0;
  padding: var(--s-4);
  background: var(--c-panel);
  border: 1px solid var(--c-ink);
  border-radius: var(--r-2);
}
.calc-result[hidden] { display: none; }
.calc-result__label {
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted);
  margin: 0 0 var(--s-2);
}
.calc-result__dim {
  display: flex; align-items: center; gap: var(--s-3);
  color: var(--c-ink);
  margin: 0 0 var(--s-2);
}
.calc-result__dim::before, .calc-result__dim::after {
  content: "";
  flex: 1 1 var(--s-5);
  min-width: var(--s-4);
  height: 22px;
  background:
    linear-gradient(currentColor, currentColor) center / 100% 1px no-repeat,
    linear-gradient(currentColor, currentColor) left center / 1px 100% no-repeat,
    linear-gradient(-55deg, transparent calc(50% - 0.75px), currentColor calc(50% - 0.75px) calc(50% + 0.75px), transparent calc(50% + 0.75px)) left center / 12px 12px no-repeat;
  transform-origin: center;
  animation: dim-draw calc(var(--m-fast) * 2) var(--m-ease) both;
}
.calc-result__dim::after { transform: scaleX(-1); animation-name: dim-draw-r; }
@keyframes dim-draw { from { transform: scaleX(0.2); opacity: 0; } to { transform: scaleX(1); opacity: 1; } }
@keyframes dim-draw-r { from { transform: scaleX(-0.2); opacity: 0; } to { transform: scaleX(-1); opacity: 1; } }
.calc-result output, .calc-result__value {
  flex: none;
  font: 800 var(--t-2xl)/1 var(--f-head);
  font-variant-numeric: tabular-nums lining-nums;
  letter-spacing: -0.01em;
  color: var(--c-ink);
}
.calc-result__unit { font-weight: 600; font-size: 0.55em; color: var(--c-ink-2); margin-left: 0.15em; letter-spacing: 0; }
.calc-result__sentence { margin: 0 0 var(--s-3); color: var(--c-ink-2); }
.calc-result__also {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr));
  gap: 0; margin: 0;
  border-top: 1px solid var(--c-line);
}
.calc-result__also > div { padding: var(--s-2) var(--s-3) var(--s-2) 0; border-bottom: 1px solid var(--c-line); }
.calc-result__also dt { font-size: var(--t-xs); color: var(--c-muted); }
.calc-result__also dd { margin: 0; font: 650 var(--t-md)/1.3 var(--f-num); font-variant-numeric: tabular-nums; }
.calc-result--empty { border-style: dashed; border-color: var(--c-line-strong); color: var(--c-muted); font-size: var(--t-sm); }
.calc-result--empty .calc-result__dim { color: var(--c-line-strong); }
.calc-result--empty .calc-result__dim::before, .calc-result--empty .calc-result__dim::after { animation: none; }
.calc-result--empty output { font-size: var(--t-xl); color: var(--c-muted); }

/* Worked steps */
.calc-steps {
  margin: var(--s-4) 0 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
  border-top: 1px solid var(--c-line);
}
.calc-steps li {
  counter-increment: step;
  display: grid; grid-template-columns: 2.25rem minmax(0, 1fr);
  gap: 0 var(--s-2);
  margin: 0;
  padding: var(--s-3) 0;
  border-bottom: 1px solid var(--c-line);
}
.calc-steps li::before {
  content: counter(step);
  grid-row: span 2;
  display: grid; place-items: center;
  width: 1.75rem; height: 1.75rem;
  font: 700 var(--t-xs)/1 var(--f-num);
  border: 1px solid var(--c-ink);
  border-radius: 50%;
}
.calc-steps__what { font-size: var(--t-sm); color: var(--c-ink-2); }
.calc-steps__math {
  font-family: var(--f-num);
  font-variant-numeric: tabular-nums slashed-zero;
  font-size: var(--t-base);
  color: var(--c-ink);
  overflow-x: auto;
}
.calc-steps__math b { font-weight: 700; }

/* Assumptions */
.calc-assumptions {
  margin: var(--s-4) 0 0;
  font-size: var(--t-sm);
  color: var(--c-ink-2);
  border-top: 1px dashed var(--c-line-strong);
  padding-top: var(--s-3);
}
.calc-assumptions summary, .calc-assumptions__title {
  font-weight: 650; color: var(--c-ink); cursor: pointer;
  min-height: 44px; display: flex; align-items: center;
}
.calc-assumptions ul { margin: var(--s-2) 0 0; }

/* ---------- 8. Figures and diagrams ---------- */
.figure { margin: var(--s-6) 0; }
.figure img, .figure svg { display: block; width: 100%; }
.figure figcaption, .figure__cap {
  margin-top: var(--s-2);
  font-size: var(--t-sm); color: var(--c-muted);
  border-top: 1px solid var(--c-line); padding-top: var(--s-2);
}
.figure figcaption b { color: var(--c-ink); font-family: var(--f-num); font-weight: 650; margin-right: var(--s-2); }
.diagram-grid {
  display: grid; gap: var(--s-4);
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 14rem), 1fr));
  margin: var(--s-6) 0;
}
.diagram-grid .figure {
  margin: 0;
  padding: var(--s-3);
  background-color: var(--c-panel);
  background-image:
    linear-gradient(var(--c-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--c-line) 1px, transparent 1px);
  background-size: 16px 16px;
  border: 1px solid var(--c-line);
}
.diagram-grid .figure figcaption { background: var(--c-panel); margin: var(--s-2) calc(var(--s-3) * -1) calc(var(--s-3) * -1); padding: var(--s-2) var(--s-3); }

/* ---------- 9. Tables and bars ---------- */
.table-wrap {
  overflow-x: auto;
  margin: var(--s-5) 0;
  border-top: 2px solid var(--c-ink);
  -webkit-overflow-scrolling: touch;
}
.table-wrap:focus-visible { outline-offset: 2px; }
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--t-sm);
  font-variant-numeric: tabular-nums lining-nums;
}
.data-table caption {
  caption-side: bottom; text-align: left;
  font-size: var(--t-xs); color: var(--c-muted);
  padding-top: var(--s-2);
}
.data-table th, .data-table td {
  padding: var(--s-2) var(--s-3);
  text-align: left; vertical-align: top;
  border-bottom: 1px solid var(--c-line);
  white-space: nowrap;
}
.data-table thead th {
  font: 700 var(--t-xs)/1.25 var(--f-body);
  letter-spacing: 0.06em; text-transform: uppercase;
  color: var(--c-ink-2);
  border-bottom: 1px solid var(--c-ink);
  vertical-align: bottom;
}
.data-table tbody th { font-weight: 600; }
.data-table .num, .data-table td[data-num] { text-align: right; font-family: var(--f-num); }
.data-table tbody tr:hover { background: var(--c-accent-soft); }
.data-table tr.is-match { background: var(--c-accent-soft); }
.data-table tr.is-match th::before { content: "\2192\00a0"; }

.bar-list { list-style: none; margin: var(--s-5) 0; padding: 0; font-size: var(--t-sm); }
.bar-list li {
  display: grid; grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--s-1) var(--s-3);
  margin: 0 0 var(--s-3);
}
.bar-list__label { color: var(--c-ink-2); }
.bar-list__value { font-family: var(--f-num); font-variant-numeric: tabular-nums; font-weight: 650; text-align: right; }
.bar-list__bar {
  grid-column: 1 / -1;
  height: 10px;
  background:
    repeating-linear-gradient(90deg, var(--c-line-strong) 0 1px, transparent 1px 10%) left bottom / 100% 4px no-repeat,
    var(--c-panel);
  border: 1px solid var(--c-line);
  position: relative;
}
.bar-list__bar > span {
  display: block; height: 100%;
  width: var(--v, 0%);
  background: var(--c-ink-2);
}
.bar-list li.is-key .bar-list__bar > span { background: var(--c-accent); }

/* ---------- 10. Notes ---------- */
.note-safety, .note-info {
  position: relative;
  margin: var(--s-6) 0 var(--s-5);
  padding: var(--s-5) var(--s-4) var(--s-3);
  border: 1px solid var(--c-line-strong);
  background: var(--c-panel);
  font-size: var(--t-base);
}
.note-safety > :last-child, .note-info > :last-child { margin-bottom: 0; }
.note-safety__label, .note-info__label {
  position: absolute; top: -0.8em; left: var(--s-3);
  display: inline-flex; align-items: center; gap: var(--s-2);
  padding: 0.25em 0.6em;
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
}
.note-info__label { background: var(--c-ink); color: var(--c-paper); }
.note-safety { border-color: var(--c-stop); border-width: 2px; }
.note-safety__label { background: var(--c-stop); color: var(--c-panel); }
.note-safety__label svg, .note-info__label svg { width: 14px; height: 14px; }
.note-safety strong { color: var(--c-stop); }

/* ---------- 11. FAQ ---------- */
.faq { margin: var(--s-6) 0; border-top: 2px solid var(--c-ink); }
.faq-item { border-bottom: 1px solid var(--c-line); }
.faq-item summary {
  list-style: none;
  display: flex; align-items: center; justify-content: space-between; gap: var(--s-4);
  min-height: 52px; padding: var(--s-3) 0;
  font: 700 var(--t-md)/1.25 var(--f-head);
  cursor: pointer;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "";
  flex: none; width: 14px; height: 14px;
  background:
    linear-gradient(currentColor, currentColor) center / 100% 2px no-repeat,
    linear-gradient(currentColor, currentColor) center / 2px 100% no-repeat;
  transition: transform var(--m-fast) var(--m-ease);
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item summary:hover { color: var(--c-ink-2); }
.faq-item__body { padding: 0 0 var(--s-4); color: var(--c-ink-2); max-width: 62ch; }
.faq-item__body > :last-child { margin-bottom: 0; }

/* ---------- 12. Products ---------- */
.product-grid {
  display: grid; gap: var(--s-4);
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 16rem), 1fr));
  margin: var(--s-5) 0;
  padding: 0; list-style: none;
}
.product-grid > li { margin: 0; }
.product {
  display: flex; flex-direction: column; gap: var(--s-3);
  height: 100%;
  padding: var(--s-4);
  background: var(--c-panel);
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-2);
}
.product__img {
  aspect-ratio: 4 / 3;
  display: grid; place-items: center;
  background: var(--c-paper);
  border: 1px solid var(--c-line);
}
.product__img img { max-height: 100%; object-fit: contain; }
.product__tag {
  align-self: flex-start;
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-ink-2);
  border: 1px solid var(--c-line-strong);
  padding: 0.3em 0.5em;
}
.product__name { font: 750 var(--t-lg)/1.15 var(--f-head); margin: 0; }
.product__specs { display: grid; grid-template-columns: auto 1fr; gap: var(--s-1) var(--s-3); margin: 0; font-size: var(--t-sm); }
.product__specs dt { color: var(--c-muted); }
.product__specs dd { margin: 0; font-family: var(--f-num); font-variant-numeric: tabular-nums; }
.product__fit { font-size: var(--t-sm); color: var(--c-ink-2); margin: 0; }
.product-cta { margin-top: auto; display: grid; gap: var(--s-2); }
.product-cta .btn { width: 100%; }
.product-cta__note { font-size: var(--t-xs); color: var(--c-muted); }
.affiliate-note {
  font-size: var(--t-sm); color: var(--c-muted);
  border-top: 1px solid var(--c-line); border-bottom: 1px solid var(--c-line);
  padding: var(--s-2) 0;
  margin: var(--s-4) 0;
}
.affiliate-note a { color: var(--c-ink-2); }

/* ---------- 13. Stat lede ---------- */
.stat-lede {
  display: grid; gap: var(--s-2) var(--s-5);
  margin: var(--s-6) 0;
  padding: var(--s-4) 0;
  border-top: 1px solid var(--c-ink);
  border-bottom: 1px solid var(--c-line);
}
.stat-lede__num {
  font: 800 var(--t-3xl)/0.95 var(--f-head);
  font-variant-numeric: tabular-nums lining-nums;
  letter-spacing: -0.02em;
  margin: 0;
}
.stat-lede__num small { font-size: 0.4em; font-weight: 600; letter-spacing: 0; color: var(--c-ink-2); margin-left: 0.15em; }
.stat-lede__text { margin: 0; color: var(--c-ink-2); max-width: 52ch; align-self: center; }
.stat-lede__src { font-size: var(--t-xs); color: var(--c-muted); grid-column: 1 / -1; margin: 0; }
@media (min-width: 40rem) {
  .stat-lede { grid-template-columns: auto minmax(0, 1fr); }
}

/* ---------- 14. Sources, related, files, embed, cite ---------- */
.sources { margin: var(--s-6) 0; font-size: var(--t-sm); color: var(--c-ink-2); }
.sources h2, .sources__title { font-size: var(--t-lg); }
.sources ol { padding-left: 1.75em; }
.sources li::marker { font-family: var(--f-num); color: var(--c-muted); }
.sources a { color: var(--c-ink-2); word-break: break-word; }
.sources time { font-family: var(--f-num); color: var(--c-muted); }

.related { margin: var(--s-6) 0; }
.related ul { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--c-ink); }
.related li { margin: 0; border-bottom: 1px solid var(--c-line); }
.related a {
  display: flex; justify-content: space-between; align-items: center; gap: var(--s-3);
  min-height: 48px; padding: var(--s-2) 0;
  text-decoration: none; font-weight: 600; color: var(--c-ink);
}
.related a::after { content: "\2192"; color: var(--c-muted); transition: transform var(--m-fast) var(--m-ease); }
.related a:hover::after { transform: translateX(3px); color: var(--c-ink); }
.related__why { display: block; font-weight: 400; font-size: var(--t-sm); color: var(--c-muted); }

.file-list { list-style: none; margin: var(--s-5) 0; padding: 0; border-top: 1px solid var(--c-ink); }
.file-list li { margin: 0; border-bottom: 1px solid var(--c-line); }
.file-list a {
  display: grid; grid-template-columns: auto minmax(0, 1fr) auto; align-items: center;
  gap: var(--s-3);
  min-height: 52px; padding: var(--s-2) 0;
  text-decoration: none; color: var(--c-ink);
}
.file-list__type {
  font: 700 var(--t-xs)/1 var(--f-num);
  letter-spacing: 0.06em;
  padding: 0.35em 0.45em;
  border: 1px solid var(--c-ink);
  min-width: 3.4em; text-align: center;
}
.file-list__name { font-weight: 600; }
.file-list__meta { font-size: var(--t-xs); color: var(--c-muted); font-family: var(--f-num); font-variant-numeric: tabular-nums; }
.file-list a:hover .file-list__name { text-decoration: underline; }

.embed-box, .cite-box {
  margin: var(--s-5) 0;
  padding: var(--s-4);
  background: var(--c-panel);
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-2);
}
.embed-box__title, .cite-box__title {
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted);
  margin: 0 0 var(--s-2);
}
.embed-box textarea, .cite-box__text {
  display: block; width: 100%;
  margin: 0 0 var(--s-3);
  padding: var(--s-3);
  font: 400 var(--t-sm)/1.5 var(--f-num);
  color: var(--c-ink);
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  border-radius: var(--r-1);
  resize: vertical;
  user-select: all;
}
.cite-box__formats { display: flex; flex-wrap: wrap; gap: var(--s-2); margin: 0 0 var(--s-3); }

/* ---------- 15. Sidebar ---------- */
.side { font-size: var(--t-sm); }
.side > * + * { margin-top: var(--s-6); }
.side__block { border-top: 2px solid var(--c-ink); padding-top: var(--s-3); }
.side__title {
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted); margin: 0 0 var(--s-2);
}
@media (min-width: 64rem) {
  .side { position: sticky; top: var(--s-5); align-self: start; }
}
.side--finder { display: none; }
@media (min-width: 64rem) {
  .side--finder { display: block; }
}
.side--finder .side__title { display: block; }
.finder__q {
  width: 100%; min-height: 46px;
  padding: 0 var(--s-3);
  font: 500 var(--t-base)/1 var(--f-body);
  color: var(--c-ink);
  background: var(--c-panel);
  border: 1px solid var(--c-line-strong); border-radius: var(--r-2);
}
.finder__q:focus { outline: none; border-color: var(--c-ink); box-shadow: 0 0 0 1px var(--c-ink); }
.finder__count { margin: var(--s-2) 0; font-size: var(--t-xs); color: var(--c-muted); }
.finder__list {
  list-style: none; margin: 0; padding: 0;
  max-height: calc(100vh - 16rem); overflow-y: auto; overscroll-behavior: contain;
  border-top: 1px solid var(--c-ink);
}
.finder__list li { margin: 0; border-bottom: 1px solid var(--c-line); }
.finder__list li[hidden] { display: none; }
.finder__list a {
  display: flex; justify-content: space-between; align-items: center; gap: var(--s-2);
  min-height: 40px; padding: var(--s-1) var(--s-1) var(--s-1) 0;
  text-decoration: none; font-weight: 600; color: var(--c-ink);
}
.finder__list a::after { content: "\2192"; color: var(--c-muted); }
.finder__list a:hover::after { color: var(--c-ink); }
.finder__more { margin: var(--s-3) 0 0; color: var(--c-muted); }

/* ---------- 16. Footer as a drawing title block ---------- */
.site-foot {
  container-type: inline-size;
  margin-top: var(--s-8);
  border-top: 2px solid var(--c-ink);
  font-size: var(--t-sm);
  color: var(--c-ink-2);
}
.site-foot__block {
  display: grid;
  grid-template-columns: 1fr;
  border-left: 1px solid var(--c-ink);
  border-right: 1px solid var(--c-ink);
  margin-block: var(--s-6);
}
.site-foot__cell {
  padding: var(--s-3) var(--s-4) var(--s-4);
  border-bottom: 1px solid var(--c-ink);
}
.site-foot__cell:first-child { border-top: 1px solid var(--c-ink); }
.site-foot__label {
  display: block;
  overflow-wrap: normal;
  font: 700 var(--t-xs)/1 var(--f-body);
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--c-muted);
  margin-bottom: var(--s-2);
}
.site-foot ul { list-style: none; margin: 0; padding: 0; }
.site-foot li { margin: 0; }
.site-foot li a { display: inline-flex; align-items: center; min-height: 36px; color: var(--c-ink-2); }
.site-foot__brand img { height: 26px; width: auto; display: block; margin-bottom: var(--s-2); }
.site-foot__brand .logo-dark { display: none; }
@media (prefers-color-scheme: dark) {
  .site-foot__brand .logo-light { display: none; }
  .site-foot__brand .logo-dark { display: block; }
}
.site-foot__fine { font-size: var(--t-xs); color: var(--c-muted); padding-bottom: var(--s-6); }
.site-foot__fine span { font-family: var(--f-num); font-variant-numeric: tabular-nums; }
@container (min-width: 36rem) {
  .site-foot__block { grid-template-columns: repeat(2, minmax(0, 1fr)); border-top: 1px solid var(--c-ink); }
  .site-foot__cell:first-child { border-top: 0; }
  .site-foot__cell:nth-child(odd) { border-right: 1px solid var(--c-ink); }
}
@container (min-width: 56rem) {
  .site-foot__block { grid-template-columns: 2fr repeat(3, minmax(0, 1fr)); border-bottom: 1px solid var(--c-ink); }
  .site-foot__cell { border-bottom: 0; border-right: 1px solid var(--c-ink); }
  .site-foot__cell:last-child { border-right: 0; }
}

/* ---------- 17. Motion safety ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---------- 18. Print: calculator results as a job-site sheet ---------- */
@media print {
  :root {
    --c-paper: #fff; --c-panel: #fff; --c-ink: #000; --c-ink-2: #222; --c-muted: #444;
    --c-line: #bbb; --c-line-strong: #666; --c-accent: #000; --c-accent-soft: #eee;
  }
  @page { margin: 14mm; }
  body { font-size: 11pt; background: #fff; color: #000; }
  .site-head, .nav-main, .nav-toggle, .crumbs, .toc, .side, .product-grid, .product,
  .affiliate-note, .embed-box, .cite-box, .related, .faq, .btn, .calc__actions,
  .calc-unit-toggle, .skip-link, .diagram-grid, .site-foot__block { display: none !important; }
  .layout { display: block; padding: 0; }
  .content { max-width: none; }
  .page-title::after { print-color-adjust: exact; -webkit-print-color-adjust: exact; }
  .calc { background: none; box-shadow: none; border: 1px solid #000; break-inside: avoid; padding: 8mm; }
  .calc-field__control { border: 0; border-bottom: 1px solid #000; border-radius: 0; }
  .calc-field__control, .calc-result, .calc-steps li { break-inside: avoid; }
  .calc-result { border: 2px solid #000; }
  .calc-result__dim::before, .calc-result__dim::after { animation: none; print-color-adjust: exact; -webkit-print-color-adjust: exact; }
  .calc-assumptions details, .calc-assumptions { display: block; }
  .calc-assumptions details > *:not(summary) { display: block !important; }
  .sources a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 8pt; word-break: break-all; }
  .site-foot { border-top: 1px solid #000; margin-top: 8mm; }
  .site-foot__fine::before { content: "Printed from builderscalcs.com. Check quantities against your supplier before ordering."; display: block; margin-bottom: 2mm; }
  h2, h3 { break-after: avoid; }
  table { break-inside: auto; }
  tr { break-inside: avoid; }
  .table-wrap { overflow: visible; }
  .data-table th, .data-table td { white-space: normal; }
}

[hidden]{display:none!important}

pre { max-width: 100%; white-space: pre-wrap; overflow-wrap: anywhere; }
pre code { overflow-wrap: anywhere; }

.figure--editorial { max-width: 720px; }
.figure--editorial img { height: auto; }
.figure__credit { display: block; margin-top: var(--s-2); }
.figure__sources { margin-top: var(--s-2); font-size: var(--t-sm); overflow-wrap: anywhere; }
.figure__sources summary { cursor: pointer; min-height: 44px; display: flex; align-items: center; }