The new dark mode for the issue bar moved to yellow buttons and an icon

to convey state, but in practice this didn't do enough to convey state.

Skimming a list of comments, it wasn't immediately clear which comments

were open and which were closed.
We now use a border around the issue bar when open. This is fairly

unobtrusive, but still stands out visually from closed banners, which

have no border and blend in more with the background.
The text color now updates to indicate the status. New design tokens

have been added for accented text colors, used in both the issue bar and

issue summary table.
The buttons have also been updated. When the issue is open, they are

yellow, but when closed, they're grey. This augments the border and

helps with a quick visual on the status.
The banner has also been given a subtly-softer border radius, reducing

the boxy look just a bit.

Tested all the issue states in light and dark modes.