What would be the proper CSS selector to target the following tag:
<nav class="twelve-col col main-menu">
Would the proper selector just be:
.twelve-col col main-menu {
}
What would be the proper CSS selector to target the following tag:
<nav class="twelve-col col main-menu">
Would the proper selector just be:
.twelve-col col main-menu {
}
 
    
     
    
    No. You should combine individual class names using .:
.twelve-col.col.main-menu
 
    
    No. Your selector is trying to find main-menu INSIDE col which is INSIDE twelve-col. But you are looking for element, that has twelve-col col main-menu classes the same time, so use .twelve-col.col.main-menu
However try BEM methodology, where you use just one class to make all your selectors same specificity (http://getbem.com)
 
    
    The most effective selector will be nav.twelve-col.col.main-menu you can also use nav.main-menu which makes some sense.
