Copy and paste the code below and save it as fillrect.svg.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20000303 Stylable//EN"
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="300" height="300">
<rect width="300" height="100"
style="fill:rgb(0,0,255);stroke-width:1;
stroke:rgb(0,0,0)"/>
</svg>

see this example here