Convert px to rem

[federicocappellotto97]

I'm loving new jit mode and I think it would be very useful to give us the possibility to convert every size in px to rem.
For example if use class .mt-[30px], that class becomes

 .my-[30px] {
   margin-top: 0.875rem; => 1*30/16 = 0.875rem;
}

Then I can set 1rem = 1vw to make every sizes (even font) responsible