The problem is that I am from Belgium (my messages were translated by google translate). I will try to describe the problem in more detail in English.
Last week I did two things: upgrade to your web 10 because I like the concept of separating design from content, and I make a home page for another website (www.rcoz.be) with bootstrap (coded by hand). So I can compare the responsiveness of both websites.
With bootstrap (www.rcoz.be), the hamburgermenu only will be shown when I make the windows the half of the normal width (this was obtained by col-md-6 , where 6 is the half of the complete width of 12 in bootstrap model. This behavior is regardless of the zoomfactor of the window. (Even by zooming with control-mouse wheel to 150% the hamburgermenu will only apair when I lessen the width of the window to the half.
With stresslabo.be , where i used web 10, responsive design Washington, I see a more fragile behavior. I tested it on 4 computers, I tried IE, I also tried the NewYork design, I started over with several empty projects. The responsiveness is different. I only see the complete menu with chrome when I zoom out to 90%, and the menu disappears when I diminish the window by a little. (In terms of bootstrap: the breakpoint to hide the menu is too big, too much to the right.
Your message helps. I checked one computer and noticed that the fontsize was changed to 141%. perhaps this can be a cause.
You can imagine I was a bit frustated in the beginning because NewYork and Washington design nearly always hide the menu.
I noticed another strange when zooming out with Washington: the complete content area shrinks in a complete different way than with bootstrap.
I zoomed out very much so you can see the effect clearly. If I did the same with www.rcoz.be (bootstrap), the content still filled the complete width.
Thank you for your answer. I didn't expect to get an answer from someone. You are doing a great job there. I suppose that the most other websites don't have that lot of pages, but your programs make it easy to make websites with a lot of pages. I also tried the non-responsive Julia design, where we don't have the problem of responsiveness.