Switch Excel Spreadsheet from Light view to Night View?

Same exact issue. Changing Office Theme settings changes the color on everything except the spreadsheet. I even checked to see if maybe for some reason my spreadsheets were being color filled white by default. I started color filling spreadsheets and changing the color of the borders to basically replicate dark mode. That was fine for my own stuff but then I realized I can't set up work spreadsheets like that or they'll think I've been replaced by Wednesday Addams. Hoping to find a solution to this. I think my work around may be adding a solid color picture to every spreadsheet, but this is a looong way from ideal. First, it's gotta be a gray or brown picture, as the font stays default black. The background does not print, but the background does stay with the file, so again, unless you're Wednesday Addams, you'll have to remove the back ground before sending it to anyone at work. Hopefully someone figures this out.