How to use a slash in less not as a division sign?

Question

HTML

I need to implement a border-radius: 21px 22px 22px 21px/21px 21px 22px 22px
on the button, but less thinks I want to divide 21px/21px.
How to fix?

Answer 1

border-radius: 21px 22px 22px 21px~"/"21px 21px 22px 22px;

lesscss.org/functions/#string-functions-e