SVG filter only working when added in style attribute (Firefox)

Question

I added a blur effect svg to my HTML(text/html):

    ...
    
        ...
        

Answer 1

In my case Firefox didn't find an SVG filter because of the CSS rule:

#svg-filters {
    display: none;
}

where svg-filters is the id of the tag containing all filters definitions. Replaced those lines with

#svg-filters {
    position: absolute;
    height: 0;
    width: 0;
}

and filters work fine in FF.

Referencing filters relative to the HTML document from CSS works fine in major browsers, as pointed out by Josh Powell in his answer.