Hi dear,hidden text comes under Black hat SEO and search engine does not give any permission to have nay hidden text in your web page,If there will be a hidden text then search engine can ban your web site on search engine.you can see hidden contents by pressing ctrl+A.Good luck.
chimps why would you even want to consider anything close to hidden text? It's a step below black hat. It's just stupid. If the text can't be clearly read on the page you will get busted sooner or later. If nothing else your competitors will report you.