how to get value of inner ,which does not have id or class slectors except parent div value?

I am working on customization of a wordpress theme ,there was a situation that,When ever user resizes the browser window text content on the page should change its color.I successfully done with this using javascript in some standalone html page .Coming to the wordpress theme,I posted the code of the block from which i want to get the text and changes its color dynamically on resize below this post.The thing is that inner span and I am working on customization of a wordpress th