Bounding Boxes for Bar Sections

[wrouesnel]

Is your feature request related to a problem? Please describe.
I'm using this entity on a dashboard which is displayed on a monochrome e-ink display.

It is perfect for this medium with only one problem: there's no rendered borders on the individual segment sections.

This means the labels are not clearly bounded if the background colors are set to "white" to get a clear rendering on the display.

Describe the solution you'd like
An option to set a border-color (and I guess width) for bar sections so transitions are clearly visible on such displays.

Describe alternatives you've considered
None that I can think of.

Additional context

This is a sample image of my current best effort rendered out to a Kindle Paperwhite sized display:

This is almost perfect. Basically it just needs the ability to draw solid bounding boxes around the segments so they'll appear on the display.