Bug: Focus ring / target size too small

[bcullman]

Is this issue related to a specific component?
TreeView

What version of the Fiori Fundamentals are you using?
1.4.2

To Reproduce
Steps to reproduce the behavior:
go to
https://sap.github.io/fundamental/components/tree.html

focus on one of the chevrons, and then use tab to gain focus on the close button.

Screenshots

Expected behavior
target area (made visible with focus ring) is 44px in height and width, minimum a11y.

to look nice, it should be square, filling the height of the entire row. a similar expand collapse chevron was used in SAP Concur's pre fundamentals library. here is where we landed: