See attached jsfiddle.
The sub header is readable (probably white, the same as the main header text).
The sub header is unreadable as it's the same colour as the background.
https://jsfiddle.net/thm9zvx2/

This is slightly out of date, please see the JSFiddle.
It works using inverted sub header. See https://jsfiddle.net/d3y0apjs/1/
I admit header is especially covered when used inside a inverted segment and sub header is not.
I remember we decided against supporting all kinds of possible content inside a inverted segment to change the color automatically on component basis (because there is basically always an inverted variant for each component), so i am not 100% sure if we should support at least sub header automatically... although an appropriate PR is done quickly
.ui.inverted.segment .sub.header {
color: #ffffff;
}
@hammy2899 @prudho @ColinFrick Your thoughts?
@lubber-de I think in this case it is inconsistent so it should be changed.
A header will be inverted if the parent component is also inverted but the sub header won't yet if the header is inverted itself the sub header will be.
Fixed by #488
See https://jsfiddle.net/yo2fpcL1/
Wow, I'm not used to this prompt response :smile:
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Wow, I'm not used to this prompt response :smile: