Incoming texts are white not gray

I was changing some color settings on my imac and browser. I now notice that my incoming messages on i messages only on my mac are white not gray. This isn't happening on my Iphone. I don't remember what I did to the color settings. Now that the messages are white, I don't see the message contained in a message bubble because the background to the text is white. I only see the blue bubble that contains my messages. The words are just there in a sentence with no border around it. How do I get the incoming messages back to gray?