I encountered an issue with the Customize section of the tool. The body area is not taking up the full available space on the page.

Issue details:
The body section only uses approximately 30% of the space from the top, and more than half of the page remains empty.
This issue affects the layout and usability of the tool, as it does not make full use of the available space for customization options.
Expected behavior:
The body section should expand to take up more space or ideally fill the remaining space to improve the user experience.

Steps to reproduce:
Open the Customize tool that generates CSS style files for forms.
Notice that the body section is not using the full space, leaving a large empty area.
Environment:
Operating System: Windows
Browser: Google Chrome