How can I apply styles to multiple classes at once?

Solution 1:

.abc, .xyz { margin-left: 20px; }

is what you are looking for.

Solution 2:

You can have multiple CSS declarations for the same properties by separating them with commas:

.abc, .xyz {
   margin-left: 20px;
}

Solution 3:

Don’t Repeat Your CSS

 a.abc, a.xyz{
    margin-left:20px;
 }

OR

 a{
    margin-left:20px;
 }

Solution 4:

If you use as following, your code can be more effective than you wrote. You should add another feature.

.abc, .xyz {
margin-left:20px;
width: 100px;
height: 100px;
} 

OR

a.abc, a.xyz {
margin-left:20px;
width: 100px;
height: 100px;
} 

OR

a {
margin-left:20px;
width: 100px;
height: 100px;
}