How are the tag colours defined? Our header colour is slate and the tag background is then slate but the font is also a dark grey making browse by tag unreadable. On hover-over its light grey and the font is then white.
On example sites including the demo site the font is white.
Bad form answering my own post but I had not specified (or I previously removed) the header text colour in Theme\Customise since I could see white in the header text. Anyhow once this change was made my tag font colour was then white.