/*
 * hairline, the one line. Unforged house identity 3.0.0 Broadside, 2026-08-22. Owner: Andreas.
 *
 * line.hairline, 1px, in the rule of the ground it sits on through the alias: rule.paper on paper
 * (1.32:1), rule.flood on the flood (1.36:1), rule.axis inside the raised step where base.css
 * swaps the alias (rule.paper measures 1.196:1 there). Two named variants for the cases the alias
 * cannot know: --axis for a chart baseline, reference line or tick (3.28:1 on the trough, under
 * the marks, never over them), and --ink for the one heavier rule the identity draws, the table
 * head's, in the ground's ink. A hairline never conveys required information alone and is never
 * thicker than line.edge. An hr or an empty div; --vertical for a divider in a row.
 */
.u-hairline {
  display: block;
  height: 0;
  margin: 0;
  border: 0;
  border-block-start: var(--u-line-hairline) solid var(--u-ground-rule);
}
.u-hairline--axis { border-color: var(--u-color-rule-axis); }
.u-hairline--ink { border-color: var(--u-ground-ink); }
.u-hairline--vertical {
  height: auto;
  width: 0;
  align-self: stretch;
  border-block-start: 0;
  border-inline-start: var(--u-line-hairline) solid var(--u-ground-rule);
}
.u-hairline--vertical.u-hairline--axis { border-color: var(--u-color-rule-axis); }
.u-hairline--vertical.u-hairline--ink { border-color: var(--u-ground-ink); }