St.chat_message border display and footprint

Hi Guys,

I need a border for st.chat_message(“ai”) UI component. The st.chat_message(“user”) has a border, it looks great. The main reason I need a border because I plan to add a footprint with a chat_message response at the bottom right position. Dose anyone know how to achieve this?
Also, is there a easy way to control a st.caption() to right align with a margin?

Many Thanks,

Jeffrey