/*
 * band, the signal field. Unforged house identity 3.1.0 Broadside, 2026-08-22. Owner: Andreas.
 *
 * A signal is a field, never type (tokens signal._note): a full bleed band carrying display type
 * in the signal's own ink, title step or above, one field per viewport, never taller than 25
 * percent of the viewport, never adjacent to a flood, never carrying a mark or a control. Primary
 * is the default and the only signal a surface shows unless it needs two: vermilion with paper
 * ink (5.79:1). --secondary is blue with paper ink (7.54:1), the second field when the primary is
 * already on the page, never the first. The tertiary is not a band: acid is the highlight field
 * behind one client literal, a bounded inline field in ink.primary at 15.81:1, Barlow 500 at the
 * head step, at most once per document, and --tertiary renders exactly that. Padding space.block,
 * the padding of a bounded field. --bleed runs a band set inside a page container out through
 * the page margin, content staying on the column; an organism outside the container does not
 * need it. The ink arrives through currentColor, so a flush block inside sets in the signal's ink.
 * --heat (since tokens 3.1.0) is the fourth value in the group and not a fourth signal: the audit
 * band's colour and nothing else, see the comment on the rule.
 */
.u-band {
  background-color: var(--u-color-signal-primary);
  color: var(--u-color-signal-primary-ink);
  padding-block: var(--u-space-block);
  transition: background-color var(--u-motion-state);
}
.u-band--secondary {
  background-color: var(--u-color-signal-secondary);
  color: var(--u-color-signal-secondary-ink);
}
.u-band--bleed {
  margin-inline: calc(-1 * var(--u-space-page));
  padding-inline: var(--u-space-page);
}
/* the tertiary is a bounded field behind one client literal, never a band */
.u-band--tertiary {
  display: inline-block;
  max-width: var(--u-measure-prose);
  padding: var(--u-space-row) var(--u-space-para);
  background-color: var(--u-color-signal-tertiary);
  color: var(--u-color-signal-tertiary-ink);
  font-family: var(--u-font-text);
  font-weight: 500;
  font-size: var(--u-size-head);
  line-height: var(--u-leading-head);
}
/* heat: the audit band's colour and nothing else (tokens signal.heat, ruling B1 of 2026-08-22). The
   one field whose ink is not paper: paper type on heat measures 2.61:1 and is banned; the field
   carries signal.heat-ink at 6.67:1 and the ink block action at 6.33:1. The four ground aliases of
   base.css section 2 are pointed at heat ink, faint included, because ink.faint measures 1.91:1 on
   heat: a label set on this field with any atom takes the field's ink. The rule alias is ink.primary,
   the hairline of the handle input (6.33:1). The band carries the audit band's statement line and no
   other line; the module around it (label, statement, handle input, action) is
   03_ORGANISMS/audit-band, and it is that module's cap, 50 percent of the viewport, that applies here
   and not the 25 percent of a signal field. Never the hero band, never a second field beside vermilion,
   never in the same viewport as vermilion, never a section ground, never on the audit surface. */
.u-band--heat {
  --u-ground-ink: var(--u-color-signal-heat-ink);
  --u-ground-ink-secondary: var(--u-color-signal-heat-ink);
  --u-ground-ink-faint: var(--u-color-signal-heat-ink);
  --u-ground-rule: var(--u-color-ink-primary);
  background-color: var(--u-color-signal-heat);
  color: var(--u-color-signal-heat-ink);
}