Add dynamic desktop picture to Safari start page background

How can I add my dynamic Big Sur desktop picture to my Safari start page background? I had it set up like that but erroneously dragged a jpeg onto the start page back ground now I can't get the dynamic Big Sur desktop picture back in place. Only the static Big Sur picture is available.. Is there a way to make the start page look transparent? I forgot what I originally did but now I'm frustrated that I can't get the look I like back. Any helpful ideas, I'd appreciate it!