OK, I think I have it.
Using the window I confirm that the home people are using the same class (whoishome) as the title window.
To get that to work properly, I changed the MMM-whoishome.js line 34 from
html = html + '<img class="person" src="' + this.config.TRACK[this.peopleArray[i][0]].image + '"> ' + this.peopleArray[i][0] + '<BR>';
to
html = html + '<img class="person" src="' + this.config.TRACK[this.peopleArray[i][0]].image + '"> <span class="person">' + this.peopleArray[i][0] + '</span><BR>';
and then the people who are home use class person, which can then be used to configure the colour separately to the header title.
@yedidia - is this something worth adding into the module for better flexibility?
Sorry I’m not good at GH, so have no idea how to submit a PR for it.