Theme Customization API

Hi WordPress

I am currently developing a WordPress theme. In functions.php I have defined this function:

add_theme_support( 'custom-background', array(
	'default-color' => 'ff0000',
) );

I have also tried this:

$args = array(
	'default-color' => 'ff0000',
);
add_theme_support( 'custom-background’, $args );

The color is just an example. It’s red.

And I followed this:
https://codex.wordpress.org/Custom_Backgrounds

When I go into the ‘Customise’, then it displays the page with a light grey color #f1f1f1. When I choose a color other than the default red #ff0000, then it works fine. When I select the default red #ff0000, then goes back to a white #ffffff. I have checked whether it is overwritten by other PHP or CSS. I don’t understand what I have done wrong and it’s damn annoying.

Do you guys have any ideas to solve this problem?

Thank you 🙂