How to set the background colour in Overpass Turbo using MapCSS?

In MapCSS 0.2, there is an option to specify a background colour using the canvas selector. But it doesn't work in Overpass Turbo for some reason:

way(if:is_closed())({{bbox}});
(._;>;);
out meta;

{{style:

canvas
{fill-color: #000000;}

node, way
{opacity:0; fill-opacity:0}

area[@version=1]
{color:red; fill-color:red; fill-opacity:1;}

}}

Does Overpass Turbo support the ability to specify a background colour? Or maybe it can be done in some other way?