/* Hybrid Heater Codes. Tokens first; everything below reads them. System fonts keep pages fast. */
:root {
  --color-bg: #f6f4f0;
  --color-surface: #ffffff;
  --color-ink: #1d2327;
  --color-ink-muted: #4a545b;
  --color-accent: #9a4321;      /* copper: 6.0:1 on bg */
  --color-on-accent: #ffffff;
  --color-band: #1f2d36;
  --color-on-band: #e9eef1;
  --color-line: #d6d1c8;
  --color-warn-bg: #fff4d6;
  --color-warn-line: #c99a1a;
  --color-focus: #1a5fb4;
  --font-body: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --measure: 68ch;
  --wrap: 60rem;
  --gutter: 1rem;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #12181c;
    --color-surface: #1b2328;
    --color-ink: #e8ecee;
    --color-ink-muted: #b3bec4;
    --color-accent: #f0996b;
    --color-on-accent: #12181c;
    --color-band: #0b1013;
    --color-line: #34414a;
    --color-warn-bg: #3a2f10;
    --color-warn-line: #c99a1a;
    --color-focus: #8ab4f8;
  }
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body { margin: 0; background: var(--color-bg); color: var(--color-ink); font-family: var(--font-body); font-size: 1.0625rem; line-height: 1.6; overflow-wrap: break-word; }
a { color: var(--color-accent); text-underline-offset: 0.18em; }
:focus-visible { outline: 3px solid var(--color-focus); outline-offset: 2px; }
main:focus { outline: none; }
.wrap { width: min(100% - 2 * var(--gutter), var(--wrap)); margin-inline: auto; }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 1rem; top: 1rem; background: var(--color-surface); padding: .5rem 1rem; z-index: 10; }

.masthead { background: var(--color-band); color: var(--color-on-band); }
.masthead-row { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .5rem 1.5rem; padding-block: .8rem; }
.brandmark { color: inherit; font-weight: 750; font-size: 1.15rem; text-decoration: none; letter-spacing: -.01em; }
.masthead ul { display: flex; gap: 1.25rem; list-style: none; margin: 0; padding: 0; }
.masthead a { color: inherit; }
.masthead :focus-visible { outline-color: var(--color-on-band); }

main { padding-block: 1.5rem 3rem; }
h1 { font-size: clamp(1.7rem, 1.2rem + 2.2vw, 2.4rem); line-height: 1.15; letter-spacing: -.015em; margin: .25rem 0 .75rem; }
h2 { font-size: 1.35rem; line-height: 1.25; margin: 2rem 0 .6rem; }
h3 { font-size: 1.08rem; margin: 0 0 .35rem; }
p, ul, ol { margin: 0 0 .9rem; }
p, li { max-width: var(--measure); }
.lede { font-size: 1.15rem; color: var(--color-ink-muted); }
.kicker { text-transform: uppercase; letter-spacing: .08em; font-size: .8rem; font-weight: 650; color: var(--color-ink-muted); margin: 0; }
.small { font-size: .9rem; color: var(--color-ink-muted); }
.cite { font-size: .9rem; color: var(--color-ink-muted); }

.crumbs ol { display: flex; flex-wrap: wrap; gap: .25rem .5rem; list-style: none; padding: 0; margin: 0 0 1rem; font-size: .9rem; color: var(--color-ink-muted); }
.crumbs li + li::before { content: "›"; margin-right: .5rem; }

.hero { padding-block: 1rem 1.5rem; }
.lookup label { display: block; font-weight: 650; margin-bottom: .35rem; }
.lookup input { width: 100%; max-width: 32rem; font: inherit; font-size: 1.2rem; padding: .7rem .9rem; border: 2px solid var(--color-line); border-radius: var(--radius); background: var(--color-surface); color: var(--color-ink); }
.lookup input:focus-visible { border-color: var(--color-focus); }
#results ul { list-style: none; padding: 0; margin: .5rem 0 0; max-width: 40rem; }
#results li { border-bottom: 1px solid var(--color-line); }
#results a { display: block; padding: .6rem .2rem; text-decoration: none; color: var(--color-ink); }
#results a strong { color: var(--color-accent); font-family: var(--font-mono); margin-right: .4rem; }
#results .small { display: block; }

.cards { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(16rem, 1fr)); gap: .75rem; }
.cards li { background: var(--color-surface); border: 1px solid var(--color-line); border-radius: var(--radius); padding: .9rem 1rem; display: flex; flex-direction: column; gap: .2rem; max-width: none; }

.table-wrap { overflow-x: auto; border: 1px solid var(--color-line); border-radius: var(--radius); background: var(--color-surface); }
table.codes { border-collapse: collapse; width: 100%; font-size: .98rem; }
.codes th, .codes td { text-align: left; vertical-align: top; padding: .6rem .8rem; border-bottom: 1px solid var(--color-line); }
.codes thead th { font-size: .85rem; text-transform: uppercase; letter-spacing: .05em; color: var(--color-ink-muted); }
.codes tbody th a { font-family: var(--font-mono); font-weight: 700; white-space: nowrap; }
.codes tr:last-child > * { border-bottom: 0; }

.meaning { font-size: 1.15rem; }
.badge { display: inline-block; font-size: .8rem; font-weight: 700; text-transform: uppercase; letter-spacing: .06em; border: 1px solid var(--color-line); border-radius: 999px; padding: .1rem .6rem; }
.safety { background: var(--color-warn-bg); border-left: 4px solid var(--color-warn-line); border-radius: 0 var(--radius) var(--radius) 0; padding: .9rem 1.1rem; margin: 1.5rem 0; }
.safety h2 { margin-top: 0; font-size: 1.1rem; }
.safety ul { margin-bottom: .4rem; }
.entries { list-style: none; padding: 0; }
.entries > li { border-top: 1px solid var(--color-line); padding-top: .9rem; margin-top: .9rem; }
.code-links { columns: 12rem; padding-left: 1.1rem; }
.sources li { font-size: .95rem; }
.ad-slot { min-height: 280px; margin: 1.5rem 0; }

.foot { background: var(--color-band); color: var(--color-on-band); padding-block: 1.5rem; font-size: .92rem; }
.foot a { color: inherit; }
.foot p { max-width: var(--measure); }
.note { border: 1px solid var(--color-line); border-left: 4px solid var(--color-accent); border-radius: 0 var(--radius) var(--radius) 0; background: var(--color-surface); padding: .8rem 1.1rem; margin: 1.25rem 0; }
.note h2 { margin-top: 0; font-size: 1.05rem; }
.tech-note { font-weight: 600; }