Newbie css duplicate reference question

[Leea]

I am a newbie and clueless. I am taking over for someone. He had two css files. In addition to other stuff both files had something similar. The first one has:

#main-content {
    position: relative;
    top: 0px;
    left: 0px;
    width: 95%;
}

and the second one has:

#main-content {
    position: relative;
    top: 0px;
    left: 200px;
    width: 80%;
}

With the two of them how do you tell which is the active command?

I learn by borrowing from others.

thanks

Lee

 

Edited August 3, 2018 by Leea
clarification

[Ingolme]

The last rule overrides the first one. There are a set of rules by which you can always determine which CSS will be used, you can read about it here: https://www.w3schools.com/css/css_specificity.asp