Fix padding and font weight for custom list items

[ang-zeyu]

What is the purpose of this pull request? (put "X" next to an item, remove the rest)

• [x] Bug fix

Fixes #1249

What is the rationale for this request?
Simply adds the custom styles used for default list items to custom list items, doing some class renaming to better differentiate the two.

Testing instructions:
custom list classes should now get the font-weight and padding styling, but without the highlight-on-hover

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Code:

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Output:

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Proposed commit message: (wrap lines at 72 characters)
Fix padding and font weight for custom list items

Padding and font weight formatting are not applied for custom list
items without nested lists or anchors.

Let's add these, and rename the classes used for better naming
consistency.

[ang-zeyu]

clean rebase above

@damithc I left the right padding as is, you could add it using the bootstrap classes easily though { .p-1/2/3/4/5 }, or overwrite the site-nav-custom-list-item class, sounds good?

[damithc]

@damithc I left the right padding as is, you could add it using the bootstrap classes easily though { .p-1/2/3/4/5 }, or overwrite the site-nav-custom-list-item class, sounds good?

Yes. Right-padding is not that important.

[ang-zeyu]

Yes. Right-padding is not that important.

ok i'll merge this in then, since it hasn't been released and just shifts some styles around