Here are some SVG icons from Ubuntu's Human theme:
type="image/svg+xml" height="48" width="48">[icon]
And here are some modified versions:
If your browser supports inline SVG and CSS2 system colors, the base color of the modified icons will match the color your machine produces when you highlight text (like this).
In Ubuntu, this will typically match your theme's main color. Try changing your theme (System > Preferences > Appearances) or selection color (Appearance Preferences > Customize > Colors > Selected items) and refreshing the page. The files are not changing in any way; they are just being rendered with different colors (the shading is just transparent bits on top of the base color). (The desktop color of the little computer icon should actually match your desktop's background color, too!) I think Gnome should render icons in the same way, with base colors derived from the theme automatically. See Brainstorm idea #5238: Simple way to change the Human theme base color.
The first eight icons just required changing a single color value to "highlight", so you can compare the two files to see the minor difference. The last five required more complex changes, and I just kludged them up in Inkscape to look good enough for this mock-up, so the file source code is drastically different from the originals.
Note that these will not work on your desktop. The base color will just be rendered as black, since Gnome/Inkscape/whatever doesn't understand the "highlight" CSS color.