/* site/style.css · Isotherm Building Science · v2, Option C
   Built 2026-08-24 under board/WEB-004 from docs/wireframe/HeroPoster.dc.html
   (Option C, approved by the principal 2026-08-24 late evening, recorded in
   docs/wireframe/APPROVED-C.md) and docs/wireframe/Mobile.dc.html for the
   390 px rules below the hero. v1 is frozen at site-versions/v1-25b3864/.

   Every color and font is a custom property and the :root block is copied from
   brand/tokens.css, so the page is one request plus fonts. No hex is written
   anywhere outside :root. The three translucent whites the artboard draws are
   color-mix over --paper and --tint, each with a solid token fallback on the
   line above it for a browser without color-mix. */

:root {
  /* palette · brand/tokens.css, from BRAND.md and the brand kit */
  --ink:      #16181A;
  --accent:   #2C6C93;
  --tint:     #8FB4CC;
  --muted:    #5A6570;
  --paper:    #FFFFFF;
  --muted-2:  #8B939C;
  --rule:     #CCD4DC;
  --card:     #F4F7FA;

  /* type · brand/logo files/README.md */
  --font-sans: "Instrument Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: "IBM Plex Mono", "SF Mono", Menlo, Consolas, monospace;
  --label-tracking: 0.22em;

  /* line weights · DECK-STYLE.md §4 */
  --hairline: 0.7px;
  --border:   1px;
  --accent-bar: 5px;

  --gutter: 120px;

  /* the entry easing, from the artboard */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

*, *::before, *::after { box-sizing: border-box; }

html { color-scheme: only light; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration: none; }
a:hover, a:focus-visible { color: var(--ink); text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }
p { margin: 0; }

/* mono labels are 11 px, never 10 · APPROVED.md deviation 5 */
.label {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: var(--label-tracking);
  text-transform: uppercase;
  color: var(--accent);
  line-height: 1.6;
  margin: 0;
}

.basis {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: var(--label-tracking);
  text-transform: uppercase;
  color: var(--muted-2);
  line-height: 1.6;
  margin: 0;
}

/* a quantity never splits from its unit across a line break */
.nb { white-space: nowrap; }

.section { padding-left: var(--gutter); padding-right: var(--gutter); }

/* ── 1 · the hero band · Option C ────────────────────────────────────────── */

.hero {
  position: relative;
  overflow: hidden;
  background: var(--ink);
  color: var(--paper);
  /* the approved band is 900 px. The cap is what keeps the mono strip inside
     the fold on a viewport shorter than 900 px, where a flat 900 px would push
     it under the edge; at 900 px and taller the two are the same number. */
  min-height: 900px;
  min-height: min(900px, 100svh);
  padding: 40px var(--gutter) 48px var(--gutter);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 48px;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 60% 50% at 30% 35%,
              color-mix(in srgb, var(--tint) 10%, transparent) 0%, transparent 70%);
  pointer-events: none;
}

.hero > * { position: relative; }

.brandbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
}

.brandbar img { width: 240px; }
.hero .label { color: var(--tint); }

.statement { display: flex; flex-direction: column; gap: 36px; }

/* 96 px at 1440, and the 1440 x 900 render is the measurement for how many
   lines it takes · board/WEB-004 predicted failure 1 */
.statement h1 {
  font-size: clamp(2.25rem, 6.6vw, 96px);
  font-weight: 600;
  line-height: 0.95;
  letter-spacing: -0.03em;
  max-width: 1200px;
  margin: 0;
  text-wrap: balance;
}

/* both ways to reach him sit in the hero, above the fold at 1440 x 900 ·
   principal, 2026-08-25: "make the phone number and email address prominent
   and easy to find" */
.cta-row { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }

.cta {
  display: inline-flex;
  align-items: center;
  min-height: 48px;
  padding: 0 28px;
  border-radius: 999px;
  border: var(--border) solid var(--muted);
  border-color: color-mix(in srgb, var(--paper) 25%, transparent);
  color: var(--paper);
  font-size: 14px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: transform 0.5s var(--ease-out), background 0.5s;
}

.cta:hover, .cta:focus-visible {
  transform: translateY(-2px);
  background: color-mix(in srgb, var(--paper) 6%, transparent);
  color: var(--paper);
  text-decoration: none;
}

/* the phone is the filled pill, the email the outlined one beside it */
.cta-solid {
  background: var(--paper);
  border-color: var(--paper);
  color: var(--ink);
  font-weight: 600;
}

.cta-solid:hover, .cta-solid:focus-visible {
  background: var(--tint);
  border-color: var(--tint);
  color: var(--ink);
}

.cta.mail-cta { text-transform: none; letter-spacing: 0; }

/* the four numbers as a mono strip at the band's foot. It wraps at 1440
   because five items at 11 px tracked 0.22 em are wider than the 1200 px
   content column; the measurement is in runs/WEB-004/desktop-1440x900.png */
.strip {
  display: flex;
  flex-wrap: wrap;
  column-gap: 40px;
  row-gap: 10px;
  border-top: var(--border) solid var(--muted);
  padding-top: 20px;
}

.strip .basis { white-space: nowrap; }
.strip .lit { color: var(--paper); }

/* the staggered entry · CSS only, and off entirely under reduced motion */
.rise { animation: rise 0.8s var(--ease-out) both; }
.rise-2 { animation-delay: 0.12s; }
.rise-3 { animation-delay: 0.24s; }
.rise-4 { animation-delay: 0.36s; }

@keyframes rise {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
  .rise { animation: none; }
  .cta { transition: none; }
  .cta:hover, .cta:focus-visible { transform: none; }
}

/* ── 2 · the numbers ─────────────────────────────────────────────────────── */

.numbers {
  padding-top: 72px;
  padding-bottom: 64px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.numbers-head { display: flex; flex-direction: column; gap: 12px; }

.numbers-head h2 {
  font-size: 30px;
  font-weight: 600;
  line-height: 1.2;
  max-width: 900px;
  margin: 0;
}

.lede { font-size: 15px; line-height: 1.5; color: var(--muted); max-width: 760px; }

.hairline { height: var(--hairline); background: var(--rule); }

.grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 24px;
  align-items: stretch;
}

.cell {
  background: var(--card);
  border: var(--border) solid var(--rule);
  border-bottom: var(--accent-bar) solid var(--accent);
  padding: 28px 24px 24px 24px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

/* the four basis labels sit on one baseline whatever the condition wraps to */
.cell .basis { margin-top: auto; }

.value {
  display: flex;
  align-items: baseline;
  gap: 8px;
  white-space: nowrap;
}

.value b {
  font-size: clamp(34px, 3.4vw, 48px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.01em;
}

.value span { font-size: 18px; color: var(--muted); }
.cond { font-size: 14px; line-height: 1.45; color: var(--ink); }

/* ── 3 and 4 · what Datum does, and about ────────────────────────────────── */

.duo {
  padding-top: 24px;
  padding-bottom: 72px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 64px;
}

.duo > div { display: flex; flex-direction: column; gap: 16px; }

.duo h2 {
  font-size: 24px;
  font-weight: 600;
  line-height: 1.25;
  margin: 0;
}

.duo p:not(.label) { font-size: 16px; line-height: 1.6; color: var(--muted); }

.hr { margin: 0 var(--gutter); height: var(--hairline); background: var(--rule); border: 0; }

/* ── 5 · contact ─────────────────────────────────────────────────────────── */

.contact {
  padding-top: 56px;
  padding-bottom: 56px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 48px;
}

.contact > div { display: flex; flex-direction: column; gap: 10px; }

.contact .tel {
  font-size: 28px;
  font-weight: 600;
  color: var(--ink);
  min-height: 44px;
  display: flex;
  align-items: center;
}

/* the email is set at the phone's weight and near its size, so neither reads
   as the secondary one · principal, 2026-08-25 */
.contact .mail {
  font-size: clamp(18px, 1.9vw, 26px);
  word-break: break-word;
}

/* ── footer ──────────────────────────────────────────────────────────────── */

.foot {
  background: var(--card);
  border-top: var(--hairline) solid var(--rule);
  padding-top: 24px;
  padding-bottom: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
}

/* 24 px is the kit's floor: "mark never below 24 px on screen"
   (docs/SITE-BRIEF.md, Brand). The artboard draws it at 18 px and v1 shipped
   18 px; the kit rule outranks the artboard. */
.foot img { width: 24px; flex: none; }

/* ── the 1100 px step: four cards to two, two columns to one ─────────────── */

@media (max-width: 1100px) {
  :root { --gutter: 56px; }
  .hero { min-height: 720px; }
  .grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .duo { grid-template-columns: minmax(0, 1fr); gap: 40px; }
  .contact { grid-template-columns: minmax(0, 1fr); gap: 32px; }
}

/* ── the 390 px rules · docs/wireframe/Mobile.dc.html, and APPROVED-C.md for
      the hero: heading clamp(2.25rem, 11vw, 3rem), the CTA full width at
      48 px, the mono strip stacked one item per line ────────────────────── */

@media (max-width: 700px) {
  :root { --gutter: 24px; }

  .hero {
    min-height: 0;
    padding-top: 28px;
    padding-bottom: 36px;
    gap: 40px;
  }
  .brandbar img { width: 200px; }
  .statement { gap: 24px; }
  .statement h1 { font-size: clamp(2.25rem, 11vw, 3rem); max-width: none; }

  .cta-row { display: block; }
  .cta { display: flex; width: 100%; justify-content: center; min-height: 48px; }

  .strip { flex-direction: column; row-gap: 8px; padding-top: 16px; }
  .strip .basis { white-space: normal; }

  .numbers { padding-top: 40px; padding-bottom: 32px; gap: 24px; }
  .numbers-head h2 { font-size: 22px; }
  .grid { grid-template-columns: minmax(0, 1fr); gap: 16px; }
  .cell { padding: 22px 20px 20px 20px; }
  .value b { font-size: 40px; }
  .value span { font-size: 16px; }

  .duo { padding-top: 8px; padding-bottom: 40px; }
  .duo h2 { font-size: 20px; }
  .duo p:not(.label) { font-size: 15px; }

  .contact { padding-top: 36px; padding-bottom: 40px; }
  .contact .tel { font-size: 26px; }
  .contact .mail { font-size: 17px; }

  .foot { padding-top: 20px; padding-bottom: 20px; align-items: flex-start; }
  .foot img { width: 24px; }
}