wp_add_inline_style()

wp_add_inline_style() — Adds extra CSS styles to a registered stylesheet. Styles will only be added if the stylesheet is already in the queue. Accepts a string $data containing the CSS. If two or more CSS code blocks are added to the same stylesheet $handle, they will be printed in the order they were added, i.e. the latter added styles can redeclare the previous.

Inputs: $handle (string): Name of the stylesheet to add the extra styles to. $data (string): String containing the CSS styles to be added.

Returns bool: True on success, false on failure.