Space exported as HTML does not resolve CSS dependencies

When exporting a space as HTML, the generated zip files contains a file /styles/site.css

This css file contains the following line, which references a file not included in the zip file:

@import 'imports/global';

Furthermore site.css contains LESS-references to certain style not defined anywhere leading to a mediocre viewing experience:

body {
color: @aui-text-color;
font-family: @aui-font-family;
font-size: @aui-font-size-medium;
...

All "@aui" references are not resolved.

As we have to export a space containing a quality management documentation for external auditing, any hint or solution how to solve this issue would be great!