Hey,
I want to present you my style I wrote for D.Tube.
To install this Style you need the browser extension "Stylish" or "Stylus" (I would suggest the latter).
Go to https://userstyles.org/styles/154575/d-tube-dark-skin and click "install Style"
If you have any suggestions or found a bug, just comment here or on the userstyles website.
Credit for the image used in the Style: Vivaldi (Browser)