Copy the styles used by `ThreadSettingsModal` in `style.css` to `thread-settings-moda.css` and "consume" `thread-settings-modal.css` in `ThreadSettingsModal`.
This already gets us closer to where we want to be.
Before:
After:
Note: The `current-tab`, `delete-tab` and `modal-radio` selectors are neither in `style.css` nor `user-settings-modal.css` (the file that `thread-settings-modal.css` was copied from). Will handle styling of these selectors in later diff.
Next diffs:
1. Remove extraneous selectors from `thread-settings-modal.css` that aren't used in the `ThreadSettingsModal` component.
2. Fill in styles that are "used" by `ThreadSettingsModal` that don't actually exist anywhere in the repo (eg `current-tab`). Probably by looking through the git history to see what `current-tab` **used** to be.
3. Style the `ThreadSettingsModal` component so it looks decent.