How to change the style of the email template of the digest?

[bts (Brendan Schlagel)]

One small thing that could be useful here: a way to change the header image size for this email. See below images — in the first (default) the header image is almost comically tiny (40px height). The latter I tried making three times larger (120px, the actual size of the uploaded image) and it looks much better. Not sure if there’s any way to do this currently but would be nice to be able to use the larger image!