Browser can not autodetect height/width of an SVG file and sets
img size to default 300x150 unless <svg> tag specifies it explicitly.
Setting width in <svg>
Setting width in <img>
Autosize SVG <img>
This example tries trick explained in
http://stackoverflow.com/a/14363879
but it fails, because <img> doesn't provide access to the
structure of underlying <svg> data.
Conclusion: use <img> only if you know real <svg>
size and don't need to change SVG content dynamically.
<object data=> tag
Notes:
300x150 bounding box indicates the same problem with autodetecting
height/width of an SVG file.
In Firefox before 70 there was
the bug
that adds 1px space between <object> border and SVG.