Syntax Error: Missing digits after the exponent symbol

[Ddystopia]

Code like that:

css!(
  font-size: 2em;
)

Cannot be parsed by Rust - Syntax Error: Missing digits after the exponent symbol. What one must do is wrap numbers in ${}:

css!(
  font-size: ${2}em;
)

Or use raw strings. But this is pretty bad user experience.

Can something be done about it? Maybe add exception for em so that code like that:

css!(
  font-size: 2 em;
)

Would result in font-size: 2em instead of font-size: 2 em?