I had a look on your GitHub and first of all thanks for sharing your work and progress, it's good. I can clearly tell that your native language seems to be german (like mine), but you should consider to write comments, picture names, classes and so on in english, especially if you want to share your work internationally.

I think you got the fundamentals right and this is great. Your HTML and CSS needs some organisation and not every attribute might be optimized yet. You have written "font: 100% georgia" for example, but operation systems without georgia installed won't load it. Still, I think you have a good foundation, keep improving!

If you have any questions just drop a message, I'll help if I can. Cheers.