I noticed that many people on the forum needed help with custom Login and Signup. By default, Anvil displays a simple alert form which is pretty nice if you do not want to do the job yourself. However, your Login page is your first impression. So you have to make it nice.
This clone link will show you how to create your own Login and Signup system. You can design it any way you want.
https://anvil.works/build#clone:FCVOED67FL34FJAI=6PBKDA3LSRDJVS4A62U74HRV
If you want any more support, please tell me.