The rows in these tables were using the styles from the `.poll`
selector, and the `position: relative` property defined there caused the
inner borders to disappear in some browsers (like Firefox).
So we're adding the `public` class to the selector; this way, it doesn't
affect elements in the admin section.
Even though it's only necessary to add the `.public` prefix to the
`.poll` selector in one place in order to fix this issue, we're doing it
everywhere for consistency.
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