Overlapping colours

Question

If you put in 3 colours with the same px value e.g.
background:-moz-linear-gradient(blue 20px. red 20px, yellow 20px)
The red gets bypassed and there is a shared line between blue and yellow. Any ideas why this is?
Why isn't there a solid line between 'blue and red' and 'red and yellow'?

Answer 1

background-image:
linear-gradient(
blue, blue 19.5px,
red 19.5px, red 20.5px,
yellow 20.5px
);