Horizontal Rule

Use the horizontal-rule patch to customize this element.

Customization

Must see the source of patch at the bottom of each patch page to understand the structure then code it still code as html native element.

There are four levels of customization, in increasing order of effort:

Patch props. Each patch exposes a small, stable set of props—typically fewer than five. Lowest friction.
Context attributes. Use dataTone, dataSize, and dataDensity on a container to shift tone, size, or density for an entire subtree without touching individual elements.
Inline override. Native-wins merge strategy: any property set directly on the element overrides the patch value.
Create a variant. Clone a similar patch and edit it. Use this only when you need a reusable custom version.

Formulas

Unit - U = fontSize / 4 - convert final values with themeSpacing(n).

Size - n = intrinsic text lines, w = wrapping level, d = density factor:

height        = (n * 6 + 2 * d * w) * U
paddingBlock  = d * w * U
paddingInline = ceil(3 / w) * d * w * U
radius        = d * w * U

Base density d = 1.5:

U	w=0	w=1	w=2	w=3
height (`n = 1`)	6	9	12	15
paddingBlock	0	1.5	3	4.5
paddingInline	3	4.5	6	4.5
radius	0	1.5	3	4.5

Tone - K = N / 2 where N is the palette length. For N = 18, K = 9.

Role	Shift	n=0
Background	parent +/- n	0
Text	bg + K	6
Border	bg + K/2	3
Hover	bg + 2K/3	4
Selected / Focus	above +/- K/3	2-4

State shift range: K/3 <= delta <= 2K/3.

horizontalRule

import { type PartialElement, toState, type ValueOrState } from "@domphy/core";
import { type ThemeColor, themeColor, themeSpacing } from "@domphy/theme";

/**
 * A thematic break rendered as a thin 1px themed line with vertical margin.
 * Apply to an `<hr>` element.
 *
 * @hostTag hr
 * @param props.color - Theme color tone (`ValueOrState<ThemeColor>`) for the rule. Defaults to "neutral".
 * @example { hr: "", $: [horizontalRule()] }
 */
function horizontalRule(
  props: { color?: ValueOrState<ThemeColor> } = {},
): PartialElement {
  const color = toState(props.color ?? "neutral", "color");

  return {
    _onInsert: (node) => {
      if (node.tagName !== "hr") {
        console.warn(`"horizontalRule" primitive patch must use hr tag`);
      }
    },
    style: {
      border: 0,
      height: "1px",
      marginInline: 0,
      marginTop: themeSpacing(3),
      marginBottom: themeSpacing(3),
      backgroundColor: (listener) =>
        themeColor(listener, "shift-4", color.get(listener)),
    },
  };
}

export { horizontalRule };

</div>