Color picker UI does not update on drag (possibly related to SSR)
Hi there — first off, thanks for making this!

I implemented this and I'm seeing the following error in console:


```
Warning: Prop `style` did not match. Server: "position:absolute;top:0px;right:0px;bottom:0px;left:0px;background:url(null) center left" Client: "position:absolute;top:0px;right:0px;bottom:0px;left:0px;background:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAAMUlEQVQ4T2NkYGAQYcAP3uCTZhw1gGGYhAGBZIA/nYDCgBDAm9BGDWAAJyRCgLaBCAAgXwixzAS0pgAAAABJRU5ErkJggg==) center left"
    in div (created by Checkboard)
    in Checkboard (created by Chrome)
```

We are using NextJS so I'm wondering if the issue comes from that.

Dragging still works in that it returns the proper value in `onChange`, but it does not update the UI so it looks like it's stuck.

![Screen Recording 2020-09-07 at 11 14 AM](https://user-images.githubusercontent.com/120388/92411110-6890d080-f0fb-11ea-9686-19be0af8a9f4.gif)
