Ideal icon size?
It seems that there's an ideal font size for the icons, at which it is rendered cleanly. For example, this is the down arrow at 12px:

![image](https://user-images.githubusercontent.com/1285584/70756610-ebcff200-1d34-11ea-92ee-fee272fb08e5.png)

and at 16px:

![image](https://user-images.githubusercontent.com/1285584/70756556-cc38c980-1d34-11ea-9ede-61cb9253f4fa.png)

so it doesn't look very good as the bottom border is wider than the top one and vice-versa.

However if I set it to 14px it looks fine:

![image](https://user-images.githubusercontent.com/1285584/70756648-0609d000-1d35-11ea-9df4-e0b7cf8f6d34.png)

So I'm wondering how to know at what size a particular icon should be rendered to look good? Is that documented somewhere?

Or perhaps are there some font settings that should be turned on (eg via css) to make sure it look good at any size?