Don't use display: inline-block inside code
Don't use display: inline-block inside code

String containing an inline-block span are not searchable in browsers.
Getting rid of display: inline-block makes the instrumentation points
visually smaller, as they no longer take up the whole line. Brighten
unvisited point background colors to compensate.

Fixes #346.

[skip ci]

aantron/bisect_ppx,aantron/bisect_ppx