How to effectively put a separate background layer in auto-layout for header of a form box

I’m trying to put this gray “rectangle” background in the header of this form in Figma (right box). The container is set in auto layout already but every time I put in this gray rectangle, it treats it as another object and messes up the layout. I’ve also tried putting a fill behind the text box, but it doesn’t completely fill up the container because there’s padding (of 32 px right/left). Was wondering if you guys have run into this before and have a solution? 🤔

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