Calendar Color Background

Does anyone know the CSS to change the background color of the dates on the calendar that are available for purchase. Right now it is a nasty green color (#ccff99). I would like to be able to change the color to something more appealing. I have tried inspecting the element and all of that but all I can really seem to change is the mouse hover over.
So far I have tried these two methods

.X {
background-color:#58cf90!important;
color:#fff;
}

*****and******

.Q {
background-color:#58cf90!important;
color:#fff;
}

if anyone knows what I need to replace the X or the Q with that would be great.

Here is the link of what I am working on. I just need to change the color of sept.15-19 from that awful green color!
http://adventureguidecertification.cloudaccess.net/wilderness-first-aid
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