If some classes couldn't be converted, add an error comment to notify.

[ADTC]

If one or more of the classes couldn't be converted, there should be an automatic error comment to notify, underneath the converted classes:

height: 2.5rem; 
color: #ffffff; 

/*
Can't convert:
border-t-[1px]
border-t-[var(--border-color)]
*/

Instead of silently leaving it out.

[ADTC]

This will be resolved by 3c2a362.