Css file failed to minifiy

One of the CSS files used by Support Central is over 1MB in size.

It appears to failed a previous minify attempt according to the first few lines.

/* Minification failed. Returning unminified contents.
(32121,33): run-time error CSS1030: Expected identifier, found ' '
@charset "UTF-8";

I found the specific location of the issue and fixed it by editing the custom.css file

One of the CSS descendant selectors/combinators on the .release_notes class has space in it that invalidates the line.

here is a side-by-side: