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

As an alternative to the important keyword, you could make the selector more specific, for example:

.left.background-none { background:none; }

(Note: no space between the class names).

In this case, the rule will apply when both .left and .background-none are listed in the class attribute (regardless of the order or proximity).