Looks very nice and clean visually. I have some suggestions from a lookup or two:
- Add support for SVCB and HTTPS records
- When you lookup CAA, you return flags as a string. It should be an integer.
- JSON is nice as an option, but I would optimise the output for people to read.
- I really like the main font. The subtitle under the logo ("A simple DNS lookup tool") looks thin in comparison. I would consider using the same chunky font for it as elsewhere. It could look nicer.
I built something similar, perhaps you can use it for further inspiration: https://www.hardenize.com/report/d53.co/1708030537#domain_dn...
It's indeed a fun little project :)