:root {
  --bg: #F5F7F4;
  --surface: #FFFFFF;
  --ink: #16222A;
  --muted: #54636C;
  --line: #D5DDD8;
  --accent: #0B6B67;
  --accent-ink: #FFFFFF;
  --accent-soft: #DDEFEC;
  --warn: #9A3412;
  --focus: #E39B00;
  --chip1: #8FB8A4;
  --chip2: #9DB7D1;
  --chip3: #E3C9A0;
  --chip4: #C9776A;
  --chip5: #5D6B7A;
  --display: "Avenir Next", "Segoe UI", "Helvetica Neue", Arial, system-ui, sans-serif;
  --text: Georgia, "Iowan Old Style", "Times New Roman", serif;
  box-sizing: border-box;
  padding-top: env(safe-area-inset-top, 0px);
  padding-bottom: env(safe-area-inset-bottom, 0px);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0E1518; --surface: #152025; --ink: #E6EEEB; --muted: #9FB0B5; --line: #26363C;
    --accent: #5CC6BC; --accent-ink: #06211F; --accent-soft: #12312F; --warn: #F2A07B; --focus: #F4C25B;
  }
}
:root[data-theme="dark"] {
  --bg: #0E1518; --surface: #152025; --ink: #E6EEEB; --muted: #9FB0B5; --line: #26363C;
  --accent: #5CC6BC; --accent-ink: #06211F; --accent-soft: #12312F; --warn: #F2A07B; --focus: #F4C25B;
}
html { scroll-padding-top: env(safe-area-inset-top, 0px); }
*, *::before, *::after { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: var(--text); font-size: 1.0625rem; line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
a { color: var(--accent); text-underline-offset: 3px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 4px; }

/* site bar */
.bar { border-bottom: 1px solid var(--line); }
.bar .wrap { display: flex; align-items: center; gap: 14px; padding-top: 14px; padding-bottom: 14px; }
.chips { display: flex; height: 26px; border-radius: 4px; overflow: hidden; flex: none; }
.chips i { display: block; width: 9px; }
.chips i:nth-child(1){ background: var(--chip1); } .chips i:nth-child(2){ background: var(--chip2); }
.chips i:nth-child(3){ background: var(--chip3); } .chips i:nth-child(4){ background: var(--chip4); }
.chips i:nth-child(5){ background: var(--chip5); }
.brand { font-family: var(--display); font-weight: 650; font-size: 1.05rem; letter-spacing: -0.01em; color: var(--ink); text-decoration: none; }


/* intro */
.intro { padding: 34px 0 24px; }
h1 {
  font-family: var(--display); font-weight: 700; letter-spacing: -0.025em; line-height: 1.04;
  font-size: clamp(2rem, 4.6vw, 3.1rem); margin: 0 0 14px; max-width: 22ch; text-wrap: balance;
}
.lede { font-size: 1.15rem; color: var(--muted); max-width: 52ch; margin: 0; }

/* calculator */
.calc { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr); gap: 36px; align-items: start; padding-bottom: 56px; }
@media (max-width: 880px) { .calc { grid-template-columns: minmax(0, 1fr); gap: 28px; } }

form { font-family: var(--display); }
fieldset { border: 0; border-top: 1px solid var(--line); margin: 0; padding: 18px 0 20px; min-width: 0; }
fieldset:first-of-type { border-top: 0; padding-top: 4px; }
legend { font-weight: 650; font-size: 1.05rem; padding: 0 0 12px; letter-spacing: -0.005em; float: left; width: 100%; }
legend + * { clear: both; }
.row { display: grid; grid-template-columns: repeat(auto-fit, minmax(128px, 1fr)); gap: 14px; }
.field label, .field .lab { display: block; font-size: .92rem; font-weight: 550; margin-bottom: 6px; }
.row-hint { font-family: var(--display); color: var(--muted); font-size: .85rem; margin: 10px 0 0; }
.hint { display: block; font-weight: 400; color: var(--muted); font-size: .85rem; }
.inp { position: relative; }
input[type="number"], select {
  width: 100%; font: inherit; font-size: 1.05rem; color: var(--ink); background: var(--surface);
  border: 1.5px solid var(--line); border-radius: 8px; padding: 11px 42px 11px 12px; min-height: 46px;
  appearance: none; -moz-appearance: textfield;
}
input[type="number"]::-webkit-outer-spin-button, input[type="number"]::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
select { padding-right: 36px; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%);
  background-position: calc(100% - 18px) 55%, calc(100% - 12px) 55%; background-size: 6px 6px, 6px 6px; background-repeat: no-repeat; }
input[type="number"]:hover, select:hover { border-color: var(--muted); }
.unit { position: absolute; right: 12px; top: 50%; transform: translateY(-50%); color: var(--muted); font-size: .9rem; pointer-events: none; }
.plain input[type="number"] { padding-right: 12px; }

.seg { display: inline-flex; border: 1.5px solid var(--line); border-radius: 8px; overflow: hidden; background: var(--surface); }
.seg label { margin: 0; }
.seg input { position: absolute; opacity: 0; pointer-events: none; }
.seg span { display: block; padding: 10px 20px; min-height: 46px; line-height: 26px; font-weight: 550; cursor: pointer; border-right: 1.5px solid var(--line); }
.seg label:last-child span { border-right: 0; }
.seg input:checked + span { background: var(--accent); color: var(--accent-ink); }
.seg input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: -3px; }

.check { display: flex; gap: 10px; align-items: flex-start; margin: 0 0 12px; font-weight: 550; cursor: pointer; }
.check input { width: 20px; height: 20px; margin: 2px 0 0; accent-color: var(--accent); flex: none; }
.sub { margin: 0 0 14px 30px; max-width: 260px; }
[hidden] { display: none !important; }

details.adv { margin-top: 4px; }
details.adv summary { cursor: pointer; font-weight: 600; padding: 6px 0; color: var(--accent); }
details.adv .row { margin-top: 10px; }
.reset { font: inherit; font-family: var(--display); font-weight: 600; background: none; border: 0; color: var(--accent); padding: 8px 0; cursor: pointer; text-decoration: underline; text-underline-offset: 3px; }

/* result */
.result { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 16px); font-family: var(--display); }
@media (max-width: 880px) { .result { position: static; } }
.chip-card { background: var(--surface); border: 1px solid var(--line); border-radius: 6px; overflow: hidden; }
.chip-top { display: flex; height: 44px; }
.chip-top i { flex: 1; display: block; }
.chip-top i:nth-child(1){ background: var(--chip1); } .chip-top i:nth-child(2){ background: var(--chip2); }
.chip-top i:nth-child(3){ background: var(--chip3); } .chip-top i:nth-child(4){ background: var(--chip4); }
.chip-top i:nth-child(5){ background: var(--chip5); }
.chip-body { padding: 22px 22px 20px; }
.chip-body h2 { font-size: 1.05rem; font-weight: 650; margin: 0 0 4px; }
.status { color: var(--muted); margin: 0; font-size: 1rem; }
.status.err { color: var(--warn); font-weight: 550; }
.item { display: grid; grid-template-columns: 150px 1fr; gap: 16px; align-items: center; padding: 16px 0; border-top: 1px solid var(--line); }
.item:first-of-type { border-top: 0; padding-top: 6px; }
.cans { display: flex; align-items: flex-end; gap: 4px; flex-wrap: wrap; min-height: 56px; }
.cans svg { display: block; }
.can-body { fill: var(--surface); stroke: var(--ink); stroke-width: 1.6; }
.can-band { fill: var(--can, var(--accent)); }
.k-ceiling { --can: var(--chip2); } .k-primer { --can: var(--chip5); } .k-walls { --can: var(--accent); }
.more { font-size: .85rem; color: var(--muted); align-self: center; }
.item-name { margin: 0; font-size: .92rem; color: var(--muted); font-weight: 550; }
.item-buy { margin: 0; font-size: 1.65rem; font-weight: 700; letter-spacing: -0.02em; line-height: 1.2; }
.item-exact { margin: 2px 0 0; font-size: .88rem; color: var(--muted); }
.cost { border-top: 1px solid var(--line); padding-top: 14px; margin: 0; font-size: .95rem; }
.cost strong { font-weight: 700; }
.steps { border-top: 1px solid var(--line); margin-top: 14px; padding-top: 10px; }
.steps summary { cursor: pointer; font-weight: 600; color: var(--accent); padding: 4px 0; }
.steps ol { margin: 10px 0 0; padding-left: 22px; font-size: .95rem; }
.steps li { margin-bottom: 6px; }
.steps b { font-weight: 650; }
.note { font-size: .85rem; color: var(--muted); margin: 12px 2px 0; font-family: var(--text); }

/* mobile summary bar */
.dock { display: none; }
@media (max-width: 880px) {
  .dock { display: flex; align-items: center; justify-content: space-between; gap: 12px; position: fixed; left: 0; right: 0; bottom: 0; z-index: 20;
    background: var(--accent); color: var(--accent-ink); font-family: var(--display); font-weight: 600;
    padding: 12px 20px calc(12px + env(safe-area-inset-bottom, 0px)); }
  .dock a { color: var(--accent-ink); font-weight: 550; white-space: nowrap; }
  body { padding-bottom: 64px; }
}
@media (max-width: 480px) { .item { grid-template-columns: 112px 1fr; } .brand { font-size: 1rem; } }
.brand { white-space: nowrap; }

/* article */
.article { border-top: 1px solid var(--line); padding: 48px 0 24px; }
.prose { max-width: 66ch; }
.prose h2 { font-family: var(--display); font-weight: 700; font-size: clamp(1.5rem, 3.4vw, 2rem); letter-spacing: -0.02em; line-height: 1.15; margin: 2.4em 0 .6em; text-wrap: balance; }
.prose h2:first-child { margin-top: 0; }
.prose p, .prose li { margin: 0 0 1em; }
.prose ul, .prose ol { padding-left: 1.3em; margin: 0 0 1.2em; }
.formula { font-family: var(--display); background: var(--accent-soft); border-left: 4px solid var(--accent); padding: 14px 16px; margin: 1.2em 0; border-radius: 0 6px 6px 0; line-height: 1.7; }
.tablewrap { overflow-x: auto; margin: 1.2em 0; max-width: 100%; }
table { border-collapse: collapse; width: 100%; min-width: 420px; font-family: var(--display); font-size: .98rem; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-weight: 650; background: var(--accent-soft); }
td.num, th.num { text-align: right; white-space: nowrap; }
tr.total td { font-weight: 700; border-top: 2px solid var(--ink); }
.faq details { border-bottom: 1px solid var(--line); padding: 4px 0; }
.faq summary { font-family: var(--display); font-weight: 600; font-size: 1.08rem; cursor: pointer; padding: 12px 0; }
.faq details p { margin: 0 0 14px; }
.sources { font-size: .95rem; color: var(--muted); }
.sources h2 { color: var(--ink); }
footer { border-top: 1px solid var(--line); padding: 26px 0 40px; color: var(--muted); font-family: var(--display); font-size: .9rem; }
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; animation: none !important; } }

/* site chrome */
.bar .wrap { flex-wrap: wrap; row-gap: 6px; }
.nav { margin-left: auto; display: flex; gap: 6px 20px; flex-wrap: wrap; font-family: var(--display); font-size: .95rem; }
.nav a { color: var(--ink); text-decoration: none; padding: 6px 0; border-bottom: 2px solid transparent; }
.nav a:hover { border-color: var(--line); }
.nav a[aria-current="page"] { border-color: var(--accent); font-weight: 600; }
.foot-nav { display: flex; flex-wrap: wrap; gap: 6px 20px; margin-bottom: 12px; }
.foot-nav a { color: var(--muted); }
.page { padding-top: 38px; padding-bottom: 60px; }
.page h1 { max-width: 26ch; font-size: clamp(1.9rem, 4.2vw, 2.8rem); }
.page .lede { margin-bottom: 30px; }
.updated { font-family: var(--display); font-size: .88rem; color: var(--muted); margin: 0 0 24px; }
.related { margin-top: 2.4em; padding-top: 1.4em; border-top: 1px solid var(--line); }
.related h2 { margin-top: 0 !important; font-size: 1.25rem !important; }
.related ul { list-style: none; padding: 0; }
.related li { margin-bottom: .5em; }
.callout { background: var(--accent-soft); border-radius: 6px; padding: 14px 16px; margin: 1.2em 0; font-family: var(--display); font-size: .98rem; }
.prose { max-width: 880px; }
.prose > * { max-width: 66ch; }
.prose > .tablewrap { max-width: 880px; }
.rooms td:first-child { white-space: nowrap; }
.skip { position: absolute; left: -999px; top: 0; background: var(--accent); color: var(--accent-ink); padding: 10px 14px; z-index: 50; font-family: var(--display); }
.skip:focus { left: 8px; top: 8px; }
.crumbs ol { list-style: none; display: flex; flex-wrap: wrap; gap: 4px 8px; padding: 0; margin: 0 0 14px; font-family: var(--display); font-size: .88rem; color: var(--muted); }
.crumbs li + li::before { content: "/"; margin-right: 8px; color: var(--line); }
.crumbs a { color: var(--muted); }
.diagram { margin: 1.6em 0; max-width: 680px; }
.diagram svg { width: 100%; height: auto; display: block; }
.diagram .dg-line { stroke: var(--ink); fill: none; stroke-width: 1.6; }
.diagram .dg-dim { stroke: var(--accent); fill: none; stroke-width: 1.4; }
.diagram .dg-room { fill: var(--accent-soft); }
.diagram .dg-wall { fill: var(--surface); }
.diagram .dg-door { fill: var(--chip3); }
.diagram .dg-win { fill: var(--chip2); }
.diagram text { font-family: var(--display); fill: var(--ink); font-size: 13px; }
.diagram .dg-cap { fill: var(--muted); font-size: 12.5px; }
.diagram .dg-accent { fill: var(--accent); font-weight: 600; }
@media (max-width: 520px) { .diagram text { font-size: 20px; } .diagram .dg-cap { font-size: 18px; } }
.diagram figcaption { font-family: var(--display); font-size: .88rem; color: var(--muted); margin-top: 8px; }
.guide-list { list-style: none; padding: 0; margin: 0; }
.guide-list li { padding: 18px 0; border-top: 1px solid var(--line); margin: 0; }
.guide-list li:first-child { border-top: 0; padding-top: 0; }
.guide-list a { font-family: var(--display); font-weight: 650; font-size: 1.2rem; letter-spacing: -0.01em; }
.guide-list p { margin: 4px 0 0; color: var(--muted); }
ol.steps-list { padding-left: 1.4em; }
ol.steps-list > li { margin-bottom: 1em; padding-left: .3em; }