I have a color and brightness picker:

It has been designed for touch interaction; you can scroll it horizontally. Now here's the thing: How do I design a good indicator for the currently selected color?

I tried some things, but I don't think they do too well.

I'd like it to be...

• simple and clean;
• the selection should be obvious;
• nice looking

The selector doesn't move at all, it's just the inner part of the selector that moves when you scroll through the colors.

Thanks in advance for your advice.