Create resizable SVG with inkscape

Inkscape currently create fixed size SVG files. Firefox does not resize them when they are set into an object tag. This is a known limitation:
https://blueprints.launchpad.net/inkscape/+spec/allow-browser-resizing

A work around is to add preserveAspectRatio and viewBox to the root svg tag:

<svg
...
width="310"
height="180"
preserveAspectRatio="xMinYMin meet"
viewBox="0 0 310 180"