thanks to the creators of this repository you can preview your work from the guthub repository. You can do this by doing the following:
in the url line type https://htmlpreview.github.io/? and append your repository url like:
https://htmlpreview.github.io/?https://github.com/Oudbier6425/modelleren_natuurkunde/blob/main/Javascript/Opdrachten/01%20Lopende%20tijd.htm
and press enter. this will show a preview of how the model will look.