Fullscreen menu bg color not solid. Why?

Hi pros, I’m struggling with a strange behavior of the background color of the full screen menu (left pop-out menu in the NAVBAR). I can’t set the color to solid (and yes, a rookie problem…). I’m afraid I’ve positioned it in the wrong place.
I appreciate any advice and help (you guys are heroes!)) Thank you very much! Joe

Here’s my read-only link:
https://preview.webflow.com/preview/jeanninegmelin-built-2025?utm_medium=preview_link&utm_source=dashboard&utm_content=jeanninegmelin-built-2025&preview=830634f63042aa40d8d488d567719007&workflow=preview