:root { color-scheme: light; --ink: #1d1d1f; --muted: #6e6e73; --line: #d2d2d7; --blue: #0071e3; }
* { box-sizing: border-box; }
body { margin: 0; background: #fff; color: var(--ink); font: 16px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; -webkit-font-smoothing: antialiased; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible { outline: 2px solid var(--blue); outline-offset: 5px; border-radius: 2px; }
.shell { width: min(1040px, calc(100% - 64px)); margin-inline: auto; }
.site-header { border-bottom: 1px solid #e8e8ed; background: #fafafa; }
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; min-height: 72px; }
.brand { display: flex; align-items: center; gap: 12px; flex-shrink: 0; }
.brand img { display: block; object-fit: contain; }
.back-link { font-size: 14px; }
.intro { max-width: 760px; padding-block: 64px 40px; }
.eyebrow { margin: 0 0 14px; color: var(--muted); font-size: 14px; font-weight: 600; }
h1 { margin: 0; font-size: clamp(36px, 4.5vw, 54px); line-height: 1.08; letter-spacing: -.045em; font-weight: 650; text-wrap: balance; }
.lead { max-width: 650px; margin: 20px 0 0; color: var(--muted); font-size: 19px; line-height: 1.5; }
.app-nav { display: flex; gap: 34px; border-bottom: 1px solid var(--line); }
.app-nav a { position: relative; padding: 14px 0; color: var(--muted); font-size: 15px; font-weight: 600; text-align: center; }
.app-nav a[aria-current] { color: var(--ink); }
.app-nav a[aria-current]::after { position: absolute; content: ""; height: 2px; background: var(--ink); bottom: -1px; left: 0; right: 0; }
.guide-heading { padding-top: 34px; }
h2 { margin: 0; font-size: 26px; letter-spacing: -.025em; line-height: 1.25; }
.guide-heading p { color: var(--muted); margin: 8px 0 24px; font-size: 14px; }
.starting-values { margin: 0; padding: 26px 30px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; background: #f5f5f7; }
.starting-values dt { color: var(--muted); font-size: 14px; }
.starting-values dd { margin: 4px 0 0; font-size: 34px; font-weight: 600; letter-spacing: -.035em; line-height: 1.2; }
.starting-values dd span { font-size: 19px; font-weight: 400; }
.value-note { color: var(--muted); font-size: 13px; max-width: 870px; margin: 14px 0 0; }
.guide-content { display: grid; grid-template-columns: minmax(0, 1.8fr) minmax(0, 1fr); gap: 64px; margin-top: 42px; }
h3 { margin: 0 0 20px; font-size: 20px; line-height: 1.3; letter-spacing: -.015em; }
.steps { list-style: none; counter-reset: steps; padding: 0; margin: 0; }
.steps li { counter-increment: steps; position: relative; padding: 0 0 26px 43px; }
.steps li::before { content: counter(steps, decimal-leading-zero); position: absolute; left: 0; top: 0; color: var(--muted); font-size: 14px; line-height: 26px; }
h4 { margin: 0 0 4px; font-size: 17px; font-weight: 600; }
.steps p { margin: 0; color: var(--muted); font-size: 15px; }
.calibration { border-left: 1px solid var(--line); padding-left: 30px; align-self: start; }
.calibration h3 { margin-bottom: 12px; }
.calibration p { font-size: 14px; color: var(--muted); margin: 0 0 18px; }
.calibration ul { list-style: none; margin: 0; padding: 0; font-size: 14px; }
.calibration li { padding: 9px 0; border-top: 1px solid #e8e8ed; }
.speed-note { border-top: 1px solid var(--line); padding-top: 25px; margin-top: 8px; }
.speed-note h3 { font-size: 17px; margin-bottom: 8px; }
.speed-note p { max-width: 870px; color: var(--muted); font-size: 14px; margin: 0; }
.speed-note strong { color: var(--ink); font-weight: 600; }
.guide-footer { display: flex; justify-content: space-between; gap: 20px; border-top: 1px solid #e8e8ed; padding: 22px 0 30px; margin-top: 48px; font-size: 13px; color: var(--muted); }
@media (max-width: 640px) {
  .shell { width: calc(100% - 40px); }
  .header-inner { min-height: 64px; gap: 12px; }
  .brand { gap: 8px; }
  .brand img:last-child { width: 76px; }
  .back-link { font-size: 12px; }
  .intro { padding-block: 38px 26px; }
  .lead { font-size: 17px; margin-top: 16px; }
  .app-nav { gap: 20px; justify-content: space-between; }
  .app-nav a { font-size: 12px; }
  .guide-heading { padding-top: 26px; }
  h2 { font-size: 23px; }
  .starting-values { padding: 20px 16px; gap: 12px; }
  .starting-values dt { font-size: 12px; }
  .starting-values dd { font-size: 27px; }
  .starting-values dd span { font-size: 14px; }
  .guide-content { grid-template-columns: 1fr; gap: 10px; margin-top: 32px; }
  .calibration { border-left: 0; border-top: 1px solid var(--line); padding: 24px 0 0; }
  .speed-note { margin-top: 24px; }
  .guide-footer { flex-direction: column; gap: 8px; margin-top: 30px; }
}