Description
The text style attributes in SVG files do not specify units for the font-size.
Chrome interprets the font-size in px, while FIrefox font-size is in pt.
When comparing to the interactive backend, it seems that Chrome does it right. In Firefox, the discrepancy leads to overlap and placement problems (labels are not centered correctly, etc.)
I don't know if this should be considered as a Firefox bug or as a matplotlib bug, but I thought this was an observation worth sharing because I spent a couple of hours trying to understand why Firefox did not display the figure correctly.
Also, the font-family is hard coded in text elements, but if the font is not available, the browser defaulkt replacement is not always a happy choice. For example, the default matplotlib sans-serif font (Bitsream Vera Sans) does not come installed by default on Ubuntu, and Firefox displays text in serif as a fallback mechanism.
Of course, all these problems occur with rcParams['svg.fonttype'] = 'svgfont'.