I'd be curious to see a screenshot of what Safari looks like. It may be a simple fix on our end.
As for file sizes, the SVG spec makes an "informational recommendation" to allow gzip-compressed SVG files. So some tools support commpression (Inkscape), and others don't (Firefox). Hopefully more will start supporting that.
As of yesterday, you can save a gzipped SVG file directly from matplotlib by specifying "svgz" as an extension.
Cheers,
Mike