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perf(PageHeader): Scope :has() selectors to direct child for O(1) lookup #7330

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perf(PageHeader): Scope :has() selectors to direct child for O(1) lookup #7330

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perf(PageHeader): Scope :has() selectors to direct child for O(1) lookup
mattcosta7 Dec 15, 2025
e8e702d
Merge branch 'main' into perf/pageheader-has-selector
mattcosta7 Dec 16, 2025
f0965a8
Merge branch 'main' into perf/pageheader-has-selector
mattcosta7 Dec 19, 2025
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7 changes: 7 additions & 0 deletions .changeset/perf-pageheader-has-selector.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
---
'@primer/react': patch
---

perf(PageHeader): Scope :has() selectors to direct child for O(1) lookup

All TitleArea and Navigation selectors are now scoped to direct children with `>` combinator.
35 changes: 18 additions & 17 deletions packages/react/src/PageHeader/PageHeader.module.css
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Expand Up @@ -33,24 +33,25 @@
line-height is calculated with calc(height/font-size) and the below numbers are from @primer/primitives.
--custom-font-size, --custom-line-height, --custom-font-weight are custom properties that can be used to override the below values.
We don't want these values to be overridden but still want to allow consumers to override them if needed.
PERFORMANCE: Scoped :has() to direct child (>) for O(1) lookup instead of descendant scan.
*/
&:has([data-component='TitleArea'][data-size-variant='large']) {
&:has(> [data-component='TitleArea'][data-size-variant='large']) {
font-size: var(--custom-font-size, var(--text-title-size-large, 2rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5)); /* calc(48/32) */

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));
}

&:has([data-component='TitleArea'][data-size-variant='medium']) {
&:has(> [data-component='TitleArea'][data-size-variant='medium']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-semibold, 600));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6)); /* calc(32/20) */

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
}

&:has([data-component='TitleArea'][data-size-variant='subtitle']) {
&:has(> [data-component='TitleArea'][data-size-variant='subtitle']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6)); /* calc(32/20) */
Expand All @@ -60,23 +61,23 @@

/* Responsive size variants */
@media (--viewportRange-narrow) {
&:has([data-component='TitleArea'][data-size-variant-narrow='large']) {
&:has(> [data-component='TitleArea'][data-size-variant-narrow='large']) {
font-size: var(--custom-font-size, var(--text-title-size-large, 2rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));
}

&:has([data-component='TitleArea'][data-size-variant-narrow='medium']) {
&:has(> [data-component='TitleArea'][data-size-variant-narrow='medium']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-semibold, 600));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
}

&:has([data-component='TitleArea'][data-size-variant-narrow='subtitle']) {
&:has(> [data-component='TitleArea'][data-size-variant-narrow='subtitle']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
Expand All @@ -86,23 +87,23 @@
}

@media (--viewportRange-regular) {
&:has([data-component='TitleArea'][data-size-variant-regular='large']) {
&:has(> [data-component='TitleArea'][data-size-variant-regular='large']) {
font-size: var(--custom-font-size, var(--text-title-size-large, 2rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));
}

&:has([data-component='TitleArea'][data-size-variant-regular='medium']) {
&:has(> [data-component='TitleArea'][data-size-variant-regular='medium']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-semibold, 600));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
}

&:has([data-component='TitleArea'][data-size-variant-regular='subtitle']) {
&:has(> [data-component='TitleArea'][data-size-variant-regular='subtitle']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
Expand All @@ -112,23 +113,23 @@
}

@media (--viewportRange-wide) {
&:has([data-component='TitleArea'][data-size-variant-wide='large']) {
&:has(> [data-component='TitleArea'][data-size-variant-wide='large']) {
font-size: var(--custom-font-size, var(--text-title-size-large, 2rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-large, 1.5));
}

&:has([data-component='TitleArea'][data-size-variant-wide='medium']) {
&:has(> [data-component='TitleArea'][data-size-variant-wide='medium']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-semibold, 600));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));

--title-line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
}

&:has([data-component='TitleArea'][data-size-variant-wide='subtitle']) {
&:has(> [data-component='TitleArea'][data-size-variant-wide='subtitle']) {
font-size: var(--custom-font-size, var(--text-title-size-medium, 1.25rem));
font-weight: var(--custom-font-weight, var(--base-text-weight-normal, 400));
line-height: var(--custom-line-height, var(--text-title-lineHeight-medium, 1.6));
Expand All @@ -137,28 +138,28 @@
}
}

&[data-has-border='true']:has([data-component='PH_Navigation'][data-hidden-all]),
&[data-has-border='true']:not(:has([data-component='PH_Navigation'])) {
&[data-has-border='true']:has(> [data-component='PH_Navigation'][data-hidden-all]),
&[data-has-border='true']:not(:has(> [data-component='PH_Navigation'])) {
border-block-end: var(--borderWidth-thin) solid var(--borderColor-default);
padding-block-end: var(--base-size-8);
}

@media (--viewportRange-narrow) {
&[data-has-border='true']:has([data-component='PH_Navigation'][data-hidden-narrow]) {
&[data-has-border='true']:has(> [data-component='PH_Navigation'][data-hidden-narrow]) {
border-block-end: var(--borderWidth-thin) solid var(--borderColor-default);
padding-block-end: var(--base-size-8);
}
}

@media (--viewportRange-regular) {
&[data-has-border='true']:has([data-component='PH_Navigation'][data-hidden-regular]) {
&[data-has-border='true']:has(> [data-component='PH_Navigation'][data-hidden-regular]) {
border-block-end: var(--borderWidth-thin) solid var(--borderColor-default);
padding-block-end: var(--base-size-8);
}
}

@media (--viewportRange-wide) {
&[data-has-border='true']:has([data-component='PH_Navigation'][data-hidden-wide]) {
&[data-has-border='true']:has(> [data-component='PH_Navigation'][data-hidden-wide]) {
border-block-end: var(--borderWidth-thin) solid var(--borderColor-default);
padding-block-end: var(--base-size-8);
}
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