Website looks weird in Chrome but not in Firefox

I started making a Website for school and I've made everything in Visual Studio Code with CSS and HTML. When I watch the Website in Firefox it looks like that:

How my Website looks in Firefox

And this is how it looks in Chrome:

How my Website looks in Chrome

I also noticed when I scroll down to 33% size in chrome, it looks nice again. So maybe everything is just too big. Idk.

I will paste my whole HTML and CSS code here now. Hopefully you can tell me what I can do better to make it look cool in both browsers.

My HTML Code: http://codepad.org/jHl7B91W

And now my CSS Code: http://codepad.org/kr734AZ2

I know the code looks bad maybe. i'm just a beginner. Hopefully you can Help me. Thanks in advance :)