/* Pareto: shared foundation. One type scale, one spacing rhythm, used by every page. */
:root {
  --ink: #1D1D1F;
  --muted: #6E6E73;
  --soft: #86868B;
  --line: #E8E8ED;
  --field: #D2D2D7;
  --bg: #FFFFFF;

  /* Type scale: six sizes, nothing else */
  --fs-display: clamp(34px, 5.4vw, 48px);  /* page headline */
  --fs-h2: clamp(24px, 3.6vw, 30px);       /* section headings, questions */
  --fs-lede: clamp(19px, 2.4vw, 21px);     /* intro paragraph under a heading */
  --fs-body: 17px;                         /* all reading text */
  --fs-label: 14px;                        /* section labels, buttons, nav */
  --fs-small: 13px;                        /* chart text, captions, footer */

  /* Spacing rhythm */
  --sp-section: 96px;
  --sp-block: 32px;
  --sp-gap: 16px;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: 'Instrument Sans', 'Helvetica Neue', Helvetica, sans-serif;
  font-size: var(--fs-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
main { max-width: 640px; margin: 0 auto; padding: 48px 24px 64px; }

/* Header */
.top { display: flex; justify-content: space-between; align-items: center; gap: 16px; }
.wordmark { font-size: 15px; font-weight: 600; letter-spacing: -0.01em; color: var(--ink); text-decoration: none; }
.navlink { font-size: var(--fs-label); font-weight: 500; color: var(--muted); text-decoration: none; }
.navlink:hover { color: var(--ink); }

/* Type */
h1, .display {
  margin: var(--sp-section) 0 0;
  font-size: var(--fs-display); line-height: 1.08; font-weight: 600; letter-spacing: -0.035em;
}
.h2 {
  margin: 0;
  font-size: var(--fs-h2); line-height: 1.2; font-weight: 600; letter-spacing: -0.025em;
}
.lede {
  margin: var(--sp-gap) 0 0;
  font-size: var(--fs-lede); line-height: 1.45; font-weight: 500; letter-spacing: -0.015em;
  color: var(--soft);
}
.lede strong { color: var(--ink); font-weight: 500; }
.label { font-size: var(--fs-label); font-weight: 500; color: var(--muted); }
.note { margin: var(--sp-gap) 0 0; font-size: var(--fs-body); line-height: 1.6; color: var(--muted); }
.strong { font-weight: 500; color: var(--ink); }

/* Sections */
.rule { margin-top: var(--sp-section); padding-top: var(--sp-block); border-top: 1px solid var(--line); }
.rule > .label + .h2, .rule > .label + .case-head { margin-top: 12px; }

/* Button */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; padding: 0 26px;
  border: 0; border-radius: 999px;
  background: var(--ink); color: #FFFFFF;
  font: inherit; font-size: 16px; font-weight: 500; line-height: 1;
  text-decoration: none; cursor: pointer;
  transition: opacity .15s ease;
}
.btn:hover { opacity: .86; }
.btn:disabled { background: var(--line); color: var(--soft); cursor: default; opacity: 1; }
.btn:focus-visible, a:focus-visible, button:focus-visible { outline: 2px solid var(--ink); outline-offset: 3px; }
.cta { margin-top: var(--sp-block); }

/* Footer */
footer { margin-top: var(--sp-section); display: flex; justify-content: space-between; font-size: var(--fs-small); color: var(--muted); }
footer a { color: var(--muted); text-decoration: none; }
footer a:hover { color: var(--ink); }