Can I change the page background color so it's easier to read?

Yes.  Script Studio has a UI Mode Toolbar that allows you to select Night Mode or a Custom Mode.

Night Mode changes the interface to a dark theme and text to white on a dark page background.

When you select Custom Mode an Options Button appears for you to configure the user-interface to suit your needs.  You can use a combination of Day Mode and Night Mode for the main elements that make up the user-interface and also the color of the text, selected text and page background.