add inline-block and bottom margin to details toggler

I tried to add a bottom margin to these when I first set them up,
because they look bad with the current spacing.

I just discovered, while working on a similar feature in another project,
that you have to set `display: inline-block` on the toggler.

Then, add a `bottom-margin` equal to line height.

Find the CSS or theme entry point that styles the details toggler, then inspect how the documentation is built with Sphinx. Update the toggler styling so it is inline-block with a bottom margin equal to the line height, and verify the rendered spacing in the documentation build.

Written by the indexing model from the issue text.