Expand/collapse all header arrows are not aligned properly

[westonruter]

The issue is more pronounced when focus styles are applied:

[archon810]

Can I propose modifying this ticket to redesign these altogether?

1. Alignment aside, these look ambiguous and broken - I thought it was an accidentally showing 2nd arrow that was out of place or something.
2. I had no idea these were collapse/uncollapse buttons. In fact, I thought they were sort up/down buttons. There are better ways to show collapse/uncollapse. For example, [+] and [-], or something similar to this but less ugly:
   

I think in general for the actual rows, it's better to use an unfilled arrow to show collapsing/uncollapsing, for example https://dribbble.com/shots/5976164-Simple-Drawer-Animation.

[csossi]

Verified in QA