I constructed my site (www.schaatsenmuseum.nl) from scratch using html only and then added a style sheet using css. This worked fine untill I started trying to make things responsive. I tried to apply what I learned with W3 schools but though I have put in many many hours I did not manage. I contacted some professionals but they appeared to be only interested in reconstructing the site with Wordpress. But that is not what I want. I want to understand the underlying system, as part of the pleasure, and do things mainly myself.. So, I hope there is some nerd around that understand and appreciate my problem and is willing to direct me to the correct trail again.
For guidance I mention that I added the viewport to the meta section and @media instructions for screens up to 600px and for 601px und up.