Edit in JSFiddle

var draw = SVG('drawing').size(500, 130)

var linear = draw.gradient('linear', function(stop) {
  stop.at(0, '#f06')
  stop.at(1, '#0f9')
})

draw.rect(100, 100).move(20, 20).radius(10).fill(linear)

var radial = draw.gradient('radial', function(stop) {
	stop.at(0, '#0f9')
  stop.at(1, '#f06')
})

draw.rect(100, 100).move(140, 20).radius(10).fill(radial)