Pagination buttons in GtkShortcutsWindow lack correct styling

### What Happened?

See for example the screenshot below of the shortcuts window for the default web browser in elementary OS called "Web". In the bottom of the window there are buttons labeled 1, 2 and 3. Issues with these buttons:

- The buttons lack margin between them
- The first button is smaller and thus not a round circle
- There are black pixels middle top and bottom on buttons 1 and 2


### Steps to Reproduce

1. Open "Web" application
2. Open "Keyboard Shortcuts" from the gear menu or press Ctrl+?

### Expected Behavior

Correct styling.

### OS Version

8.x (Circe)

### Session Type

Classic Session (X11, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

_No response_