Wordpress Developer Custom Background Options - php

Question

I've been reading the WordPress codex on adding custom background options, like in this example
$defaults = array(
'default-color' => '',
'default-image' => '',
'default-repeat' => '',
'default-position-x' => '',
'default-attachment' => '',
'wp-head-callback' => '_custom_background_cb',
'admin-head-callback' => '',
'admin-preview-callback' => ''
);
add_theme_support( 'custom-background', $defaults );
The generated output then looks exactly like this:
<style type="text/css" id="custom-background-css">
body.custom-background { background-color: #bdd96e; }
</style>
This won't work because of the complexity of my theme, i need to be able to change the above snippet so it will override the default background for .menu-wrapper tag, is there a way I can change the default CSS selector to target a different tag instead of body?

Answer 1

What is in the callback function _custom_background_cb? Is that part of core WP?
I'm completely guessing here but I think you'll want to define a function that is called to return the output you want. You'll need to adjust for admin-head-callback, & admin-preview-callback too.
Try something like this but you might need to do some research on the callback parameters.
$defaults = array(
// ...
'wp-head-callback' => 'my_custom_function',
// ...
);
add_theme_support( 'custom-background', $defaults );
function my_custom_function()
{
$html = "<style type="text/css" id="custom-background-css">";
$html += " #my-selector { background-color: #bdd96e; }";
$html += "</style>";
return $html;
}