WordPress at a glance
function is not described

_custom_logo_header_styles() WP 4.5.0

Adds CSS to hide header text for custom logo, based on Customizer setting.

This is an internal function for using it by WP core itself. It's not recommended to use this function in your code.

No Hooks.

Return

null. Nothing.

Usage

_custom_logo_header_styles();

Changelog

Since 4.5.0 Introduced.

Code of _custom_logo_header_styles() WP 5.7.2

<?php
function _custom_logo_header_styles() {
	if ( ! current_theme_supports( 'custom-header', 'header-text' ) && get_theme_support( 'custom-logo', 'header-text' ) && ! get_theme_mod( 'header_text', true ) ) {
		$classes = (array) get_theme_support( 'custom-logo', 'header-text' );
		$classes = array_map( 'sanitize_html_class', $classes );
		$classes = '.' . implode( ', .', $classes );

		$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
		?>
		<!-- Custom Logo: hide header text -->
		<style id="custom-logo-css"<?php echo $type_attr; ?>>
			<?php echo $classes; ?> {
				position: absolute;
				clip: rect(1px, 1px, 1px, 1px);
			}
		</style>
		<?php
	}
}