:root {
  --paper: #f6f5f1;
  --card: #fbfaf8;
  --ink: #161a1d;
  --muted: #4b5359;
  --accent: #4d6b86;
  --rule: #cfcac0;
  --chip: #eceae4;
  --sans: system-ui, "Segoe UI", Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: clamp(1rem, 0.97rem + 0.18vw, 1.0625rem);
  line-height: 1.62;
}

p, li, h1, h2, h3, .brand-domain { overflow-wrap: anywhere; }

h1, h2, h3 { font-weight: 600; letter-spacing: -0.022em; line-height: 1.1; margin: 0; }

a { color: var(--accent); }

svg { max-width: 100%; height: auto; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.wrap {
  width: 100%;
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 4vw, 3rem);
}

.section { padding-block: clamp(3.5rem, 8vw, 7rem); border-top: 1px solid var(--rule); }

.skip {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
}

.skip:focus {
  position: static;
  width: auto;
  height: auto;
  margin: 0;
  clip-path: none;
  display: inline-block;
  padding: 0.6rem 1rem;
  background: var(--ink);
  color: var(--paper);
}

/* ---------- header ---------- */

.site-head { padding-block: 1.35rem; border-bottom: 1px solid var(--rule); }

.head-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.75rem 2rem;
  justify-content: space-between;
}

.head-inner > * { min-width: 0; }

.brand { margin: 0; display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.25rem 0.85rem; }

.brand > * { min-width: 0; }

.brand-name { font-size: 1.125rem; font-weight: 600; letter-spacing: -0.02em; }

.brand-domain { font-size: 0.8125rem; color: var(--muted); letter-spacing: 0.06em; }

.site-nav ul { display: flex; flex-wrap: wrap; gap: 0.35rem 1.4rem; margin: 0; padding: 0; list-style: none; }

.site-nav li { min-width: 0; }

.nav-list a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9375rem;
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

.nav-list a:hover { color: var(--ink); border-bottom-color: var(--rule); }

/* ---------- hero ---------- */

.hero { padding-block: clamp(2.25rem, 4.5vw, 3.75rem) clamp(2.5rem, 5vw, 4rem); }

.hero-grid { display: grid; gap: clamp(2rem, 4vw, 3.25rem); align-items: center; }

.hero-grid > * { min-width: 0; }

.eyebrow {
  margin: 0 0 1.1rem;
  font-size: 0.78125rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 { font-size: clamp(2rem, 5vw, 3.4rem); max-width: 18ch; }

.lede { margin: 1.4rem 0 0; color: var(--muted); max-width: 46ch; font-size: 1.0625em; }

.chips { display: flex; flex-wrap: wrap; gap: 0.5rem; list-style: none; margin: 1.6rem 0 0; padding: 0; }

.chips li {
  min-width: 0;
  background: var(--chip);
  border: 1px solid var(--rule);
  border-radius: 999px;
  padding: 0.22rem 0.8rem;
  font-size: 0.8125rem;
  color: var(--muted);
}

.chips-wide { margin-top: 2.2rem; font-variant-numeric: tabular-nums; }

.chip-caption { margin: 0.7rem 0 0; font-size: 0.85rem; color: var(--muted); }

.vf-read { font-family: var(--sans); font-size: 13px; fill: var(--muted); letter-spacing: 0.05em; }

/* ---------- section split ---------- */

.split { display: grid; gap: clamp(1.5rem, 3.5vw, 3.5rem); }

.split > * { min-width: 0; }

.split-label .meta {
  margin: 0 0 0.6rem;
  font-size: 0.78125rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.split-label h2 { font-size: clamp(1.5rem, 2.6vw, 1.9rem); }

.split-body > p { margin: 0 0 1.15rem; max-width: 62ch; }

.split-body > p:last-child { margin-bottom: 0; }

.notes, .steps { margin: 1.6rem 0 0; padding-left: 1.3rem; max-width: 62ch; }

.notes { list-style: none; padding-left: 0; }

.notes li { border-top: 1px solid var(--rule); padding-top: 1rem; margin-top: 1rem; }

.notes li:first-child { border-top: 0; padding-top: 0; margin-top: 0; }

.steps li { margin-bottom: 1rem; padding-left: 0.35rem; }

.steps li::marker { color: var(--accent); font-variant-numeric: tabular-nums; }

.notes strong, .steps strong { display: block; font-weight: 600; }

/* ---------- calculator ---------- */

.calc {
  margin-top: 2.4rem;
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: clamp(1.25rem, 3vw, 1.9rem);
  max-width: 44rem;
}

.calc-title { font-size: 1.05rem; }

.calc-base { margin: 0.7rem 0 1.5rem; font-size: 0.9rem; color: var(--muted); }

.calc-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 16rem), 1fr));
  gap: 1rem;
}

.field { margin: 0; display: grid; gap: 0.4rem; min-width: 0; }

.field label { font-size: 0.8125rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }

.field select {
  width: 100%;
  max-width: 100%;
  font: inherit;
  font-variant-numeric: tabular-nums;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 0.55rem 0.7rem;
  transition: border-color 150ms ease;
}

.field select:hover { border-color: var(--accent); }

.calc-result {
  margin: 1.6rem 0 0;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.4rem 1.1rem;
}

.calc-result > * { min-width: 0; }

.calc-result-label { font-size: 0.8125rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }

#shutter {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
}

.calc-note { margin: 0.8rem 0 0; font-size: 0.9rem; color: var(--muted); max-width: 54ch; }

.no-js { margin: 1.1rem 0 0; font-size: 0.9rem; color: var(--muted); max-width: 54ch; }

html.js .no-js { display: none; }

/* ---------- footer ---------- */

.site-foot { border-top: 1px solid var(--rule); padding-block: 2.5rem 3.5rem; }

.foot-inner .brand { margin-bottom: 0.7rem; }

.foot-line { margin: 0; color: var(--muted); font-size: 0.9rem; max-width: 54ch; }

/* ---------- wide layout ---------- */

@media (min-width: 56rem) {
  .hero-grid { grid-template-columns: minmax(0, 1.12fr) minmax(0, 1fr); }
  .split { grid-template-columns: minmax(0, 15rem) minmax(0, 1fr); }
  .split-label { position: sticky; top: 2rem; align-self: start; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}