Hi @Illia_Sakharau! Welcome to the community. 
There's currently no native way to prevent the root window from passing down its styles when using the HTML component. 
I do think it's worth talking to the team about this, though, as I think there could be wider interest in such a feature.
In the meantime, you likely have a couple of options. The first solution that comes to mind is to overwrite those inherited styles using the all property, instead of having to overwrite them individually. I wasn't able to get this working in my initial testing, but I don't consider myself a CSS master by any means.
The other solution I thought of is probably overkill but definitely works - use a custom component to render the HTML content in a nested iframe.
I'll definitely talk to the team about baking in a native solution, but hopefully the above ends up being helpful. Let me know if you have any follow-up questions!