Problems with font color and plugins

I Need Help
1

Hey Folks,

been working quite a while with blocs. I really like it.
I’ve already a running Website with WordPress CMS but now facing issues with font coloring while using Plugins.

My theme background is dark, which is why text, nav links, headings, text in buttons, etc. has the color white. Problem is that when I now install a plugin like Events Calendar or embed the cookiebanner from cookiebot it falls back on the styling of the theme which displays white text on a white background.

Correct me if I am wrong:
My thought now is to style the global coloring to black and the single text passages, text in buttons etc. using a additional class to white. Should then a plugin or the cookie banner display text, this accesses the global styling and the text of thus would be black.

As i found out, blocs add a global styling:

h1,h2,h3,h4,h5,h6,p,label,.btn,a{
	font-family:"Helvetica";
	color:#FFFFFF!important;
}

If i change the global styling to:

h1,h2,h3,h4,h5,h6,p,label,.btn,a{
	font-family:"Helvetica";
	color: black;
}

…but also add a class like:

custom-theme-text-coloring{
	color:#FFFFFF!important;
}

…it should be working?

If not what would be your way to go?

Best regards Zinksa