Theme preview: Style variations exceed container width, creating horizontal scrollbar

[Clorith]

Describe the bug
The style variations in the theme previewer uses a grid display, but the two column layout causes a horizontal scroll bar.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://wordpress.org/themes/twentytwentyfour/preview/
2. Observe the sidebar with style variations and patterns, and a horizontal scrollbar at the bottom.

Expected behavior
The style variation buttons should either shrink in size to fit within the container, or collapse into a single column.

Screenshots

Desktop (please complete the following information):

• OS: Windows 10 (22H2)
• Browser: Google Chrome
• Browser Version: 125.0.6422.142
• Browser: Microsoft Edge
• Browser Version: 126.0.2592.61
• Browser: Firefox
• Browser Version: 127.0.1

Additional context
Tested on relatively large resolution desktop monitors with 1920px and 2560px widths. This appears to happen due to the vertical scrollbar in the left hand sidebar being present, when switching to responsive mode in dev tools, where the scrollbar behaves like on a non-desktop device, or as is the default on Mac's, the horizontal scroll is not there.

[ryelle]

I noticed this while fixing #140, so it'll be fixed on production shortly :)