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			_wp_normalize_relative_css_links is private and should not be used in themes or plugins directly.
_wp_normalize_relative_css_links › WordPress Function
Since5.9.0
Deprecatedn/a
› _wp_normalize_relative_css_links ( $css, $stylesheet_url )
| Access: | 
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| Parameters: (2) | 
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| Returns: | 
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| Defined at: | 
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| Codex: | 
Makes URLs relative to the WordPress installation.
Source
function _wp_normalize_relative_css_links( $css, $stylesheet_url ) {
	return preg_replace_callback(
		'#(url\s*\(\s*[\'"]?\s*)([^\'"\)]+)#',
		static function ( $matches ) use ( $stylesheet_url ) {
			list( , $prefix, $url ) = $matches;
			// Short-circuit if the URL does not require normalization.
			if (
				str_starts_with( $url, 'http:' ) ||
				str_starts_with( $url, 'https:' ) ||
				str_starts_with( $url, '/' ) ||
				str_starts_with( $url, '#' ) ||
				str_starts_with( $url, 'data:' )
			) {
				return $matches[0];
			}
			// Build the absolute URL.
			$absolute_url = dirname( $stylesheet_url ) . '/' . $url;
			$absolute_url = str_replace( '/./', '/', $absolute_url );
			// Convert to URL related to the site root.
			$url = wp_make_link_relative( $absolute_url );
			return $prefix . $url;
		},
		$css
	);
}