Hi folks!

I also noticed the following:

If the built-in web part (say, "Experiment Runs (Flow)" is first on the page) and my web part ("OpenCyto Visualization") is second, then they both get their widths correctly, whereas if I have "OpenCyto Visualization" first (on its own it's fine) and then add the "Experiment Runs (Flow)" web part, then the latter get stretched excessively horizontally outside the browser screen (horizontal scroll bars, of course, appear) and "OpenCyto Visualization" web part's inner container (my own code) is of the right size, as it should be, but the outer web part (the border) is stretched the same width as the "Experiment Runs (Flow)" below (thus there is lots of white space between the right edge of the inner container (my own code) and the right edge of the outer web part. See the attached screen capture (the horizontal scroll bars are not shown).

Feel free to check out my web part via this link: https://github.com/ldash/OpenCytoVisualization.git

Would anyone know, what the deal is?

Thanks a bunch.
-Leo