Chromatic aberration

How to use it

Put solid drop-shadows behind a shape in opposite directions, and colour them with complimentary colours.

When to use it

This adds visual interest, and is a chance to use brand colours if you happen to have complimentary colours in your palette. It also helps a technological/futuristic theme.

What to watch out for

It's best to keep the shadows close to the main shape to get the right effect. Since the shadows are solid they might interfere with layout/alignment.