Describe the bug
I believe the ARIA role attribute for the gutter should be set to separator and not slider. The slider role is meant for inputs where a user will select a value within a given range (think an input with type="range"). The separator role seems more appropriate as it is meant to separate and distinguish sections of content.

I'll be submitting a PR to fix this. Please merge if you deem I'm correct in my understanding of these roles.

To Reproduce
N/A