Firefox Does Not Animate SVG Size Changes

We've implemented a web page with an SVG illustration that's manipulated by Javascript code. It's working in all major browsers. The CSS transition attribute is used to animate the

Solution 1:

You cannot animate attributes with CSS animation and in SVG 1.1 (which Firefox implements) y and width are attributes. In SVG 2 they are CSS properties. Chrome (and its clone Opera) is currently the only UA to have implemented this part of SVG 2.

For Firefox support you'll have to use SMIL. There are polyfills to add SMIL support to Chrome.