Quellen zu Tutorials und Infos die beim Bau unserer Website benutzt wurden:

Stackoverflow - How to remove white border around the div
w3schools - CSS Buttons
w3schools - CSS Image Text
w3schools - CSS Text shadow
selfhtml - CSS Positionierung z-index
stackoverflow - header hiding behind content when position is fixed
w3schools - Background Image
w3schools - HTML Tables
labnol - How to Use a YouTube Video as your Webpage Background
w3schools - CSS background-image Property
w3schools - How TO - Shake an Image