CF 2016 cfgrid column header color cannot be changed

I have a CF 2016 site that uses html cfgrid tags. They all display white text on a grey/silver background. The headertextcolor attribute has no affect. The site was recently upgraded from CF9 and it still works on CF9. On CF9 the site didn't specify a headertextcolor and the color defaulted to black but I am also able to change the column header color with the headertextcolor tag. I have tested the same CF 2016 site on both a Windows Server 2012 R2 Datacenter/IIS server production installation and a Linux OpenSuse 42.2 developer installation.

Haven't found anything related to this on the Internet. Please help.