Theme Horse

Hi @marcus-johnson,

There is no issue on the code that you used. It should work. First please let us know in which pages you want the changes. Frontend or the backend (wp-admin).
Note: Although those margins wont be seen by normal viewer of your website.

Thanks

The theme styles will not control for the backend pages. You have to use the plugin to control for it. Please use this plugin to remove the admin bar.
after installing the plugin go to its setting and paste the below Custom CSS code to Admin CSS field.

html.wp-toolbar {
	padding-top: 0;
}
#wpadminbar {
	display: none;
}

and if you are already using some other plugin to remove the admin bar in backend then please add the below CSS Code to it.

html.wp-toolbar {
	padding-top: 0;
}

Thanks