The CSS !important rule is used to add importance to a property/value to override all styling rules for that specific property on that element.

In the following, we have three rules for styling a paragraph. The browser will normally apply the last rule it finds. However, because the first rule uses an #id, it has more specificity than the second rule which uses a .class and the final rule which just uses the <p> tag. So the browser will apply the first rule and the text will be red.

p#my_paragraph {
    color: red;
}
p.my_paragraph {
    color: blue;
}
p {
    color: green;
}

In the following we have the same three rules, but for the third, with the weakest specificity, we add the !important rule. This means that even though it is the least specific of the rules, the browser will use it because it has “added importance” which gives it precedence over the others.

p#my_paragraph {
    color: red;
}
p.my_paragraph {
    color: blue;
}
p {
    color: green !important;
}