The comment tooltips shown in reviewable content was inheriting the dark

mode styling for syntax-highlighted code in comments, which clashed with

the forced light-mode colors of the tooltip.
We now force the Ink theme to light mode on these tooltips, ensuring we

get the colors we expect.
While here, I made the tooltips a bit more readable. The style for these

hasn't changed since Review Board 1.0. To just aid in readability some,

and fix some regressions, I've added some standard padding along the

tooltip, fixed the code blocks to align with the rest of the text, and

decreased the line height so that there aren't huge gaps. There's also

a minimum width set.
I had also noticed that we had overridden a CSS variable for syntax

highlighting within the reviews CSS. This has been removed, ensuring

we're always using the theme.

Created some tooltips with paragraph content and syntax-highlighted

content. Made sure that they looked correct.
Verified that Python's self was no longer black in a code block when

in dark mode, and instead used the syntax highlighting theme.