:root {
  --primary: #2456E8;
  --primary-soft: #2456E81A;
  --ink: #13213C;
  --muted: #4E5D78;
  --line: #E3E8EF;
  --soft: #F4F7FB;
  --teal: #0E8C7E;
  --teal-soft: #E2F4F1;
  --coral: #D2562A;
  --coral-soft: #FCEDE6;
  --coral-ink: #A8401B;
  --navy-deep: #0C1830;
  --mint: #9FE3D8;
  --placeholder: #8A96AB;

  /* Layout tokens: stepped down at the 1024px and 640px breakpoints below. */
  --gutter: clamp(48px, 8.34vw, 120px); /* 120px at the 1440 design width */
  --space-xl: 120px;
  --space-l: 104px;
  --space-m: 96px;
  --h1: clamp(52px, 4.45vw, 64px); /* 64px at 1440 */
  --h2: clamp(38px, 3.06vw, 44px); /* 44px at 1440 */
  --band-pad: 56px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body {
  margin: 0;
  background: #FFFFFF;
  color: var(--ink);
  font-family: "Plus Jakarta Sans", "Segoe UI", system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); }
a:hover { color: #1A3FB0; }
a:focus-visible, button:focus-visible, summary:focus-visible, input:focus-visible, select:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 3px;
}
h1, h2, h3, p, figure, ol, ul { margin: 0; }
ol, ul { padding: 0; list-style: none; }
svg { max-width: 100%; height: auto; }
[hidden] { display: none !important; }

.page { width: 100%; max-width: 1440px; margin: 0 auto; display: flex; flex-direction: column; }
.sprite { position: absolute; width: 0; height: 0; overflow: hidden; }

.skip-link {
  position: absolute; top: 12px; left: 12px; z-index: 100;
  padding: 12px 18px; background: var(--ink); color: #FFFFFF; border-radius: 10px;
  font-weight: 700; text-decoration: none;
  transform: translateY(-200%);
}
.skip-link:focus { transform: none; color: #FFFFFF; }

/* ---------- Shared type and components ---------- */

.eyebrow {
  align-self: flex-start; display: inline-flex; align-items: center;
  height: 30px; padding: 0 14px; border-radius: 999px;
  background: var(--primary-soft); color: var(--primary);
  font-size: 13px; font-weight: 700; letter-spacing: 0.02em;
}
.eyebrow--on-dark { background: rgba(255,255,255,0.1); color: var(--mint); }
.eyebrow--on-coral { background: #FFFFFF; color: var(--coral-ink); }

.section-title {
  font-size: var(--h2); line-height: 1.12; font-weight: 800; letter-spacing: -0.03em; color: var(--ink);
}
.section-title--on-dark { color: inherit; }
.lead { font-size: 18px; line-height: 1.65; color: var(--muted); }
.body-text { font-size: 17.5px; line-height: 1.7; color: var(--muted); }
.body-text--sm { font-size: 16.5px; line-height: 1.65; }
.note { font-size: 14px; color: var(--muted); }

.stack { display: flex; flex-direction: column; gap: 20px; }
.stack--6 { gap: 6px; }
.stack--8 { gap: 8px; }
.stack--16 { gap: 16px; }
.stack--28 { gap: 28px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  height: 52px; padding: 0 22px; border-radius: 14px;
  font-size: 16px; font-weight: 700; text-decoration: none; white-space: nowrap;
}
.btn--lg { height: 56px; padding: 0 26px; }
.btn--primary { background: var(--primary); color: #FFFFFF; border: none; }
.btn--primary:hover { background: #1A3FB0; color: #FFFFFF; }
.btn--secondary { background: #FFFFFF; color: var(--ink); border: 1px solid var(--line); }
.btn--secondary:hover { color: var(--ink); border-color: #C9D2DF; }
.btn--start { align-self: flex-start; }
.btn--light { height: 50px; background: #FFFFFF; color: var(--ink); }
.btn--light:hover { color: var(--ink); background: #E4EAF4; }

.icon-tile {
  flex-shrink: 0; display: flex; align-items: center; justify-content: center;
  width: 48px; height: 48px; border-radius: 14px; background: var(--primary-soft);
}
.icon-tile--teal { background: var(--teal-soft); }

.link-strong { font-weight: 700; }
.text-link { display: inline-flex; align-items: center; gap: 8px; font-size: 15px; font-weight: 700; text-decoration: none; }

/* Section heading row: title on the left, supporting copy or action on the right. */
.section-head { display: flex; justify-content: space-between; align-items: flex-end; gap: 40px; }
.section-head__aside { max-width: 420px; }
.section-head__aside--wide { max-width: 440px; }

/* 12-column split used by most two-column sections. Stacks below 1024px. */
.grid-12 { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); column-gap: 24px; row-gap: 48px; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-12 { grid-column: span 12; }
.start-6 { grid-column: 6 / span 7; }
.start-7 { grid-column: 7 / span 6; }

/* Equal-column card grids. */
.cols { display: grid; gap: 20px; }
.cols--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.cols--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.cols--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.cols--6 { grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 16px; }
.cols--tight { gap: 16px; }

.section { padding: var(--space-l) var(--gutter); }
.section--soft { background: var(--soft); }

/* ---------- Header and navigation ---------- */

.site-header {
  position: relative;
  display: flex; justify-content: space-between; align-items: center;
  height: 84px; padding: 0 var(--gutter);
  background: #FFFFFF; border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; color: var(--ink); }
.brand:hover { color: var(--ink); }
.brand svg { flex-shrink: 0; }
.brand__text { display: flex; flex-direction: column; line-height: 1.1; }
.brand__name { font-size: 19px; font-weight: 800; letter-spacing: -0.02em; }
.brand__tagline { font-size: 12px; font-weight: 500; color: var(--muted); }

.site-nav { display: flex; gap: 8px; align-items: center; font-size: 15px; font-weight: 600; }
.nav-link { padding: 10px 14px; color: var(--ink); text-decoration: none; border-radius: 10px; }
.nav-link:hover { color: var(--ink); background: var(--soft); }
.nav-cta { height: 46px; margin-left: 12px; padding: 0 20px; border-radius: 12px; font-size: 15px; font-weight: 600; }

.nav-toggle {
  display: none; align-items: center; gap: 8px;
  height: 44px; padding: 0 14px; border: 1px solid var(--line); border-radius: 12px;
  background: #FFFFFF; color: var(--ink); font: inherit; font-size: 15px; font-weight: 700; cursor: pointer;
}
.nav-toggle__close { display: none; }
.nav-open .nav-toggle__open { display: none; }
.nav-open .nav-toggle__close { display: block; }

/* ---------- Hero ---------- */

.hero { align-items: center; padding: var(--space-m) var(--gutter) var(--space-l); background: var(--soft); }
.hero__title { font-size: var(--h1); line-height: 1.05; font-weight: 800; letter-spacing: -0.035em; color: var(--ink); }
.hero__title span { color: var(--primary); }
.hero__lead { max-width: 540px; font-size: 20px; line-height: 1.6; color: var(--muted); }
.hero__actions { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.trust-row { display: flex; flex-wrap: wrap; gap: 8px 20px; align-items: center; padding-top: 8px; font-size: 14px; color: var(--muted); }
.trust-row span { display: flex; align-items: center; gap: 8px; }
.trust-row svg { flex-shrink: 0; }

.families {
  display: flex; flex-direction: column; gap: 16px; padding: 28px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 28px;
  box-shadow: 0 24px 60px rgba(19,33,60,0.08);
}
.families__head { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.families__head > div:first-child { display: flex; flex-direction: column; gap: 2px; }
.families__kicker { font-size: 13px; font-weight: 700; color: var(--muted); }
.families__title { font-size: 22px; font-weight: 800; letter-spacing: -0.02em; }
.families__label { flex-shrink: 0; padding: 6px 12px; background: var(--primary-soft); color: var(--primary); border-radius: 999px; font-size: 13px; font-weight: 700; }
.families__legend { display: flex; flex-wrap: wrap; gap: 8px 16px; font-size: 12.5px; color: var(--muted); }
.families__legend span { display: flex; align-items: center; gap: 6px; }
.families__legend .families__disclaimer { margin-left: auto; }
.swatch { width: 10px; height: 10px; border-radius: 50%; }
.swatch--carbon { background: var(--ink); }
.swatch--fluorine { background: var(--teal); }
.swatch--oxygen { background: var(--coral); border-radius: 3px; }

.mini-card {
  display: flex; flex-direction: column; gap: 14px; padding: 20px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 20px;
  box-shadow: 0 1px 2px rgba(19,33,60,0.04), 0 8px 24px rgba(19,33,60,0.06);
}
.mini-card__names { display: flex; flex-direction: column; gap: 4px; }
.mini-card__name { font-size: 16px; font-weight: 700; line-height: 1.3; }
.mini-card__sub { font-size: 13px; color: var(--muted); }

.mol-well { display: flex; align-items: center; justify-content: center; height: 88px; border-radius: 14px; }
.mol-well--lg { height: 104px; border-radius: 16px; }
.mol-well--coral { background: var(--coral-soft); }
.mol-well--teal { background: var(--teal-soft); }

.tag { align-self: flex-start; padding: 6px 10px; border-radius: 8px; font-size: 12.5px; font-weight: 700; }
.tag--coral { background: var(--coral-soft); color: var(--coral); }
.tag--teal { background: var(--teal-soft); color: var(--teal); }

/* ---------- Lessons ---------- */

.learn { display: flex; flex-direction: column; gap: 40px; padding: var(--space-m) var(--gutter); }
.lesson-card {
  display: flex; flex-direction: column; gap: 18px; padding: 28px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 22px;
  color: var(--ink); text-decoration: none;
}
.lesson-card:hover { color: var(--ink); border-color: #C9D2DF; }
.lesson-card__top { display: flex; justify-content: space-between; align-items: center; }
.lesson-card__meta { font-size: 13px; font-weight: 700; color: var(--muted); }
.lesson-card__title { font-size: 21px; font-weight: 800; letter-spacing: -0.02em; line-height: 1.25; }
.lesson-card__text { font-size: 16px; line-height: 1.55; color: var(--muted); }
.lesson-card__link { display: flex; align-items: center; gap: 8px; margin-top: auto; font-size: 15px; font-weight: 700; color: var(--primary); }

/* ---------- Funding disclosure band ---------- */

.disclosure-wrap { padding: 0 var(--gutter); }
.disclosure {
  display: grid; grid-template-columns: auto 1fr auto; gap: 32px; align-items: center;
  padding: 36px 40px; background: var(--ink); border-radius: 28px; color: #FFFFFF;
}
.disclosure__icon { display: flex; align-items: center; justify-content: center; width: 64px; height: 64px; background: rgba(255,255,255,0.1); border-radius: 18px; }
.disclosure__body { display: flex; flex-direction: column; gap: 8px; }
.disclosure__title { font-size: 22px; font-weight: 800; letter-spacing: -0.02em; }
.disclosure__text { font-size: 16.5px; line-height: 1.6; color: #C8D2E3; }

/* ---------- Lesson 1: definition ---------- */

.definition { padding: var(--space-xl) var(--gutter) var(--space-m); row-gap: 40px; }
.diagram-panel { display: flex; flex-direction: column; gap: 12px; padding: 28px; background: var(--soft); border-radius: 24px; }
.diagram-panel__label { font-size: 14px; font-weight: 700; color: var(--muted); }
.diagram--narrow { display: none; }

.source-card {
  display: flex; flex-direction: column; gap: 10px; padding: 22px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 18px;
  color: var(--ink); text-decoration: none;
}
.source-card:hover { color: var(--ink); border-color: #C9D2DF; }
.source-card__org { font-size: 13px; font-weight: 700; color: var(--primary); }
.source-card__title { font-size: 15.5px; line-height: 1.5; font-weight: 600; }
.source-card__cta { display: flex; align-items: center; gap: 6px; margin-top: auto; font-size: 14px; font-weight: 700; color: var(--muted); }

/* ---------- Lesson 2: compare families ---------- */

.compare { display: flex; flex-direction: column; gap: 40px; }
.family-card {
  display: flex; flex-direction: column; gap: 18px; padding: 24px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 24px;
}
.family-card__head { display: flex; flex-direction: column; gap: 4px; }
.family-card__title { font-size: 20px; font-weight: 800; letter-spacing: -0.02em; line-height: 1.25; }
.family-card__sub { font-size: 14px; color: var(--muted); }
.fact { display: flex; flex-direction: column; gap: 6px; }
.fact--foot { margin-top: auto; }
.fact__label { font-size: 12px; font-weight: 800; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.fact__text { font-size: 15px; line-height: 1.55; }
.fact--foot .fact__text { color: var(--muted); }
.concern { padding: 16px; border-radius: 14px; }
.concern--coral { background: var(--coral-soft); }
.concern--coral .fact__label { color: var(--coral); }
.concern--teal { background: var(--teal-soft); }
.concern--teal .fact__label { color: var(--teal); }

/* ---------- Lesson 3: cooling ---------- */

.cooling { padding: var(--space-xl) var(--gutter); }
.cooling__intro { align-self: center; }
.callout { display: flex; align-items: center; gap: 14px; padding: 18px 20px; background: var(--teal-soft); border-radius: 16px; }
.callout svg { flex-shrink: 0; }
.callout__text { font-size: 15.5px; line-height: 1.5; }

.tank-figure { display: flex; flex-direction: column; justify-content: center; align-items: center; gap: 20px; padding: 32px; background: var(--soft); border-radius: 28px; }
.tank-legend-wrap { display: none; }

.commitments__head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 12px 24px; }
.commitments__title { font-size: 24px; font-weight: 800; letter-spacing: -0.02em; }
.commit-card { display: flex; flex-direction: column; gap: 14px; padding: 24px; background: #FFFFFF; border: 1px solid var(--line); border-radius: 20px; }
.commit-card__title { font-size: 18px; font-weight: 800; letter-spacing: -0.01em; }
.commit-card__text { font-size: 15px; line-height: 1.55; color: var(--muted); }

/* ---------- Policy timeline ---------- */

.policy { display: flex; flex-direction: column; gap: 48px; }
.review-pill {
  display: flex; align-items: center; gap: 10px; padding: 10px 16px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 12px;
  font-size: 14px; font-weight: 600; color: var(--muted);
}
.review-pill::before { content: ""; flex-shrink: 0; width: 8px; height: 8px; border-radius: 50%; background: var(--teal); }

.timeline {
  position: relative;
  display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 28px;
  padding: 36px; background: #FFFFFF; border: 1px solid var(--line); border-radius: 24px;
}
.timeline::before { content: ""; position: absolute; top: 46px; left: 48px; right: 48px; height: 2px; background: var(--line); }
.timeline__item { position: relative; display: flex; flex-direction: column; gap: 12px; }
.timeline__dot { width: 22px; height: 22px; border-radius: 50%; background: #FFFFFF; border: 3px solid var(--primary); }
.timeline__item--current .timeline__dot { background: var(--primary); border: 4px solid var(--primary-soft); }
.timeline__year { font-size: 22px; font-weight: 800; letter-spacing: -0.02em; color: var(--ink); }
.timeline__item--current .timeline__year { color: var(--primary); }
.timeline__text { font-size: 15px; line-height: 1.55; color: var(--muted); }

/* ---------- What we don't dispute ---------- */

.dispute-wrap { padding: var(--space-l) var(--gutter) 0; }
.dispute { padding: var(--band-pad); background: var(--coral-soft); border-radius: 32px; row-gap: 32px; }
.dispute-item { display: flex; gap: 16px; padding: 24px; background: #FFFFFF; border-radius: 20px; }
.check-tile { flex-shrink: 0; display: flex; align-items: center; justify-content: center; width: 36px; height: 36px; background: var(--coral-soft); border-radius: 10px; }
.dispute-item__title { font-size: 17px; font-weight: 800; }
.dispute-item__text { font-size: 15.5px; line-height: 1.55; color: var(--muted); }

/* ---------- Supplier questions ---------- */

.questions { padding: var(--space-xl) var(--gutter); }
.question-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); column-gap: 32px; border-top: 1px solid var(--line); }
.question { display: flex; gap: 14px; align-items: flex-start; padding: 18px 0; border-bottom: 1px solid var(--line); }
.question__num {
  flex-shrink: 0; display: flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; background: var(--primary-soft); color: var(--primary);
  border-radius: 9px; font-size: 14px; font-weight: 800;
}
.question__text { font-size: 16.5px; line-height: 1.5; font-weight: 600; padding-top: 3px; }

/* ---------- FAQ ---------- */

.faq-list { display: flex; flex-direction: column; padding: 8px 32px; background: #FFFFFF; border: 1px solid var(--line); border-radius: 24px; }
.faq { border-bottom: 1px solid var(--line); }
.faq summary {
  display: flex; justify-content: space-between; align-items: center; gap: 24px;
  padding: 24px 0; font-size: 18px; font-weight: 700; color: var(--ink); cursor: pointer; list-style: none;
}
.faq summary::-webkit-details-marker { display: none; }
.faq__answer { padding: 0 60px 24px 0; font-size: 16.5px; line-height: 1.7; color: var(--muted); }
.faq-badge {
  flex-shrink: 0; display: flex; align-items: center; justify-content: center;
  width: 36px; height: 36px; border-radius: 10px;
  background: var(--soft); color: var(--primary); font-size: 20px; font-weight: 600;
}
.faq-badge::before { content: "+"; }
.faq[open] .faq-badge { background: var(--primary-soft); }
.faq[open] .faq-badge::before { content: "\2212"; }

/* ---------- Guide signup ---------- */

.guide { padding: var(--space-xl) var(--gutter) var(--space-l); }
.guide__card { align-items: center; padding: var(--band-pad); background: var(--ink); border-radius: 32px; color: #FFFFFF; }
.guide__lead { font-size: 17.5px; line-height: 1.65; color: #C8D2E3; }
.checklist { display: flex; flex-direction: column; gap: 12px; font-size: 16px; color: #E4EAF4; }
.checklist li { display: flex; align-items: center; gap: 12px; }
.checklist svg { flex-shrink: 0; }

.guide-download { display: flex; flex-direction: column; gap: 24px; padding: 36px; background: #FFFFFF; border-radius: 24px; color: var(--ink); }
.guide-download__file { display: flex; align-items: center; gap: 16px; }
.guide-download__name { font-size: 20px; font-weight: 800; letter-spacing: -0.02em; line-height: 1.25; }
.guide-download__meta { font-size: 14px; font-weight: 600; color: var(--muted); }
.guide-download .btn { width: 100%; }
.guide-download__note { font-size: 15px; line-height: 1.5; color: var(--muted); }

/* ---------- Members ---------- */

.members { display: flex; flex-direction: column; gap: 36px; padding: 0 var(--gutter) var(--space-xl); }
/* Members normally sits under the guide band; give it its own top spacing when the guide is hidden. */
.guide[hidden] + .members { padding-top: var(--space-xl); }
.members__intro { max-width: 620px; }
.logo-tile {
  display: flex; align-items: center; justify-content: center; height: 96px; padding: 0 12px;
  background: #FFFFFF; border: 1px solid var(--line); border-radius: 18px;
  font-size: 13px; font-weight: 700; color: var(--placeholder); text-align: center;
}

/* ---------- 404 page ---------- */

.not-found { flex-grow: 1; display: flex; align-items: center; min-height: calc(100vh - 84px); }
.not-found .stack { max-width: 720px; }

/* ---------- Footer ---------- */

.site-footer { flex-grow: 1; display: flex; flex-direction: column; gap: 48px; padding: 72px var(--gutter) 40px; background: var(--navy-deep); color: #A9B5CA; }
.footer-top { display: flex; justify-content: space-between; gap: 48px; }
.footer-about { display: flex; flex-direction: column; gap: 16px; max-width: 420px; }
.footer-about__tagline { font-size: 26px; font-weight: 800; letter-spacing: -0.02em; color: #FFFFFF; }
.footer-about__text { font-size: 15px; line-height: 1.6; }
.footer-cols { display: flex; gap: 72px; }
.footer-col { display: flex; flex-direction: column; gap: 12px; }
.footer-col__heading { font-size: 13px; font-weight: 800; letter-spacing: 0.06em; text-transform: uppercase; color: var(--placeholder); }
.footer-col a { font-size: 15px; color: #E4EAF4; text-decoration: none; }
.footer-col a:hover { color: #FFFFFF; text-decoration: underline; }
.footer-bottom { display: flex; justify-content: space-between; gap: 32px; padding-top: 24px; border-top: 1px solid #22314F; font-size: 13.5px; }
.footer-bottom > :last-child { flex-shrink: 0; }

/* =========================================================
   Narrow desktop: 1025px to 1339px. The two-column splits stay,
   but grids nested inside a half-width column drop to one column.
   ========================================================= */
@media (min-width: 1025px) and (max-width: 1339px) {
  .definition .cols--3,
  .dispute .cols--2,
  .question-list { grid-template-columns: minmax(0, 1fr); }
}

/* =========================================================
   Tablet: 1024px and below
   ========================================================= */
@media (max-width: 1024px) {
  :root {
    --gutter: 48px;
    --space-xl: 96px;
    --space-l: 88px;
    --space-m: 80px;
    --h1: 52px;
    --h2: 38px;
    --band-pad: 40px;
  }

  /* Menu button replaces the inline nav once scripting is available. */
  .site-header { height: 72px; }
  .js .nav-toggle { display: inline-flex; }
  .js .site-nav {
    display: none;
    position: absolute; top: 100%; left: 0; right: 0; z-index: 20;
    flex-direction: column; align-items: stretch; gap: 4px;
    padding: 12px var(--gutter) 24px;
    background: #FFFFFF; border-bottom: 1px solid var(--line);
    box-shadow: 0 16px 32px rgba(19,33,60,0.08);
  }
  .js .nav-open .site-nav { display: flex; }
  .js .nav-link { padding: 12px 14px; font-size: 16px; }
  .js .nav-cta { margin: 8px 0 0; height: 52px; }
  /* Without JS the links stay visible and wrap under the brand. */
  html:not(.js) .site-header { height: auto; flex-wrap: wrap; gap: 8px; padding-top: 16px; padding-bottom: 16px; }
  html:not(.js) .site-nav { flex-wrap: wrap; }

  .grid-12 > * { grid-column: 1 / -1; }
  .section-head { flex-direction: column; align-items: flex-start; gap: 20px; }
  .section-head__aside, .section-head__aside--wide { max-width: 640px; }

  .hero__lead { max-width: 640px; }

  .cols--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .cols--3 > :last-child:nth-child(odd) { grid-column: 1 / -1; }
  .cols--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .cols--6 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

  .disclosure { grid-template-columns: auto 1fr; padding: 32px; gap: 20px 24px; }
  .disclosure .btn { grid-column: 2; justify-self: start; }

  /* Timeline turns vertical: dot on the left, line running down behind the dots. */
  .timeline { --tl-gap: 28px; grid-template-columns: 1fr; gap: var(--tl-gap); padding: 32px; }
  .timeline::before { display: none; }
  .timeline__item:not(:last-child)::after {
    content: ""; position: absolute; left: 10px; width: 2px;
    top: 25px; bottom: calc(-1 * var(--tl-gap) - 3px); background: var(--line);
  }
  .timeline__item { display: grid; grid-template-columns: 22px 1fr; column-gap: 20px; row-gap: 6px; }
  .timeline__dot { grid-row: 1 / span 2; margin-top: 3px; }
  .timeline__item--current .timeline__dot { margin-top: 3px; }

  .dispute { border-radius: 28px; }
  .guide__card { border-radius: 28px; }

  .footer-top { flex-direction: column; }
  .footer-cols { flex-wrap: wrap; gap: 40px 72px; }
}

/* =========================================================
   Mobile: 640px and below
   ========================================================= */
@media (max-width: 640px) {
  :root {
    --gutter: 20px;
    --space-xl: 72px;
    --space-l: 64px;
    --space-m: 56px;
    --h1: 40px;
    --h2: 30px;
    --band-pad: 24px;
  }

  .brand { gap: 10px; }
  .brand svg { width: 36px; height: 36px; }
  .brand__name { font-size: 17px; }
  .brand__tagline { font-size: 11.5px; }
  .site-header { height: 68px; }
  .nav-toggle { padding: 0 12px; }

  .lead { font-size: 17px; }
  .body-text { font-size: 16.5px; }
  .grid-12 { row-gap: 40px; }

  .hero__lead { font-size: 18px; }
  .hero__actions .btn { flex: 1 1 100%; }
  .families { padding: 16px; border-radius: 22px; gap: 14px; }
  .families__head { align-items: flex-start; }
  .families__title { font-size: 19px; }
  .families .cols--2 { gap: 10px; }
  .families__legend .families__disclaimer { margin-left: 0; flex-basis: 100%; }
  /* Mini cards go horizontal: molecule on the left, name and tag on the right. */
  .mini-card {
    display: grid; grid-template-columns: clamp(72px, 32%, 104px) minmax(0, 1fr); column-gap: 12px; row-gap: 8px;
    align-items: start; padding: 12px; border-radius: 16px;
  }
  .mini-card .mol-well { grid-row: 1 / span 2; align-self: center; height: 72px; padding: 0 6px; border-radius: 12px; }
  .mini-card__name { font-size: 15px; hyphens: auto; overflow-wrap: break-word; }
  .tag { font-size: 12px; }

  .cols--2, .cols--3, .cols--4 { grid-template-columns: minmax(0, 1fr); }
  .cols--3 > :last-child:nth-child(odd) { grid-column: auto; }
  .cols--6 { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }

  .learn, .compare { gap: 32px; }
  .lesson-card { padding: 24px; }

  .disclosure { grid-template-columns: 1fr; padding: 24px; border-radius: 22px; }
  .disclosure__icon { width: 52px; height: 52px; border-radius: 14px; }
  .disclosure .btn { grid-column: 1; }
  .disclosure__title { font-size: 20px; }
  .disclosure__text { font-size: 16px; }

  /* Diagrams switch to stacked versions so labels stay readable. */
  .diagram-panel { padding: 16px; border-radius: 20px; }
  .diagram--wide { display: none; }
  .diagram--narrow { display: block; width: 100%; }
  .tank-figure { padding: 16px 16px 20px; border-radius: 20px; }
  .tank-legend-wrap { display: block; align-self: stretch; }
  .tank-legend {
    display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px 16px;
    padding: 0 4px; font-size: 14px; font-weight: 700;
  }
  .tank-legend li { display: flex; align-items: center; gap: 10px; }
  .step-badge {
    flex-shrink: 0; display: flex; align-items: center; justify-content: center;
    width: 26px; height: 26px; border-radius: 50%; color: #FFFFFF; font-size: 13px;
  }
  .step-badge--1 { background: var(--coral); }
  .step-badge--2 { background: #9AA6BA; }
  .step-badge--3 { background: var(--teal); }
  .step-badge--4 { background: var(--primary); }

  .commitments__title { font-size: 21px; }

  .timeline { --tl-gap: 24px; padding: 24px 20px; }
  .timeline__year { font-size: 20px; }

  .dispute { border-radius: 22px; }
  .dispute-item { padding: 20px; gap: 14px; }

  .question-list { grid-template-columns: minmax(0, 1fr); }
  .question__text { font-size: 16px; }

  .faq-list { padding: 4px 20px; border-radius: 20px; }
  .faq summary { gap: 16px; padding: 20px 0; font-size: 17px; }
  .faq__answer { padding: 0 0 20px; font-size: 16px; }

  .guide__card { border-radius: 22px; }
  .guide-download { padding: 20px; gap: 20px; border-radius: 18px; }
  .guide-download__name { font-size: 18px; }

  .members { gap: 28px; }
  .logo-tile { height: 80px; }

  .site-footer { gap: 36px; padding-top: 56px; padding-bottom: 32px; }
  .footer-about__tagline { font-size: 22px; }
  .footer-cols { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px 24px; }
  .footer-bottom { flex-direction: column; gap: 12px; }
}