Change an SVG's color by editing fill and stroke, either as attributes or through CSS. Simple in theory. In practice there are three places a color can be declared in the same file, they follow the normal CSS cascade, and if you don't know that, "I changed the fill and nothing happened" turns into a twenty-minute debugging session.
Here's the part of SVG color handling that usually doesn't get spelled out.
fill and stroke are separate properties
Every shape has an inside (fill) and an outline (stroke), set independently:
<circle cx="50" cy="50" r="40" fill="#3366ff" stroke="#000" stroke-width="2" />
