Base64 for that would be:
url('data:image/svg+xml;base64,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');
using a tool like http://www.base64encode.org/
This doesn't answer your question directly, but it does let us do the following. We can now test to see if:
.icon:hover .style0 {
fill: red;
}
will work, or use
.icon {
background-image: url('data:image/svg+xml;base64,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');
height: 40px;
width: 40px;
}
.icon:hover {
background-image: url('data:image/svg+xml;base64,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');
}
which seems inefficient to me because we are forced to replicate a lot of the same information for the hover when all we want to change is the color.
working example