How to override the properties of a CSS class using another CSS class

Question

I am fairly new to CSS3 and I want to be able to do the following:

When I add a class into a an element, it overrides the properties of another class used in this sp

Answer 1

LIFO is the way browser parses CSS properties..If you are using Sass declare a variable called as

"$header-background: red;"

use it instead of directly assigning values like red or blue. When you want to override just reassign the value to

"$header-background:blue"

then

background-color:$header-background;

it should smoothly override. Using "!important" is not always the right choice..Its just a hotfix