Header Color Theme with Project Plugins

Hello there,
i would like to add a color theme to my prototype, so the header in the mobile browser will habe a specific color, for example red. Therefore i added a meta line in the “Head” Location of Axure Cloud’s Project Plugins.
<meta name="theme-color" content="#ff0000">
After publishing the file i can see the line in the last position of the but the color of the header didn’t change to red. Any ideas?
Best,
Timon