Modify SVG fill color when being served as Backgro

Question

Placing the SVG output directly inline with the page code I am able to simply modify fill colors with CSS like so:

polygon.mystar {
    fill: blue;
}​

circle.mycircle {
    fill: green;
}

This works great, however I'm looking for a way to modify the "fill" attribute of an SVG when it's being served as a BACKGROUND-IMAGE.

html {      
    background-image: url(../img/bg.svg);
}

How can I change the colors now? Is it even possible?

For reference, here are the contents of my external SVG file:

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
     width="320px" height="100px" viewBox="0 0 320 100" enable-background="new 0 0 320 100" xml:space="preserve">
<polygon class="mystar" fill="#3CB54A" points="134.973,14.204 143.295,31.066 161.903,33.77 148.438,46.896 151.617,65.43 134.973,56.679 
    118.329,65.43 121.507,46.896 108.042,33.77 126.65,31.066 "/>
<circle class="mycircle" fill="#ED1F24" cx="202.028" cy="58.342" r="12.26"/>
</svg>

Answer 1

In some (very specific) situations this might be achieved by using a filter. For example, you can change a blue SVG image to purple by rotating the hue 45 degrees using filter: hue-rotate(45deg);. Browser support is minimal but it's still an interesting technique.

Demo

Answer 2

This is my favorite method, but your browser support must be very progressive. With the mask property you create a mask that is applied to an element. Everywhere the mask is opaque, or solid, the underlying image shows through. Where it’s transparent, the underlying image is masked out, or hidden. The syntax for a CSS mask-image is similar to background-image.look at the codepenmask