What does !important mean in CSS? Is it available in CSS 2? CSS 3? Where is it supported? All modern browsers?
Using the !important keyword in CSS is a way to prevent other meddlesome programs from taking liberties to interpret your html/css in a way other than what you want. For example when someone goes to print your html/css to paper-and-ink, they often want the background-color property to be white to save ink. So the program overrides your background-color property. This !important keyword ...
So when using important, ideally this should only ever be used, when really really needed. So to override the declaration, make the style more specific, but also with an override.
2 Strictly speaking you shouldn't need to use !important if you've structured your CSS well and don't have too many degrees of specificity. The most appropriate time to use !important is when you have one exceptional style that you want to style outside of your site's normal cascade.
You can specify the 'more important' .imp2 class above the others with !important on it. This makes the property with the additional imp2 class more important than the .prop1.imp1 style because it is loaded first in the css.
"important account alert" notification icon won't go away When using Google on Windows/Firefox, there is a yellow "!" icon on my avatar, and when I hover over the avatar, it shows my email and says "important account alert." I'm not sure what that is.
No, it's not possible. !important is thought to be an instrument of last resort and as such should be used sparingly. !important ing whole selectors would caricature that idea. If you need to trump other styles, use CSS specificity to your advantage. You can use, e.g., these techniques to push your style declarations to the top: double class name will trump single class name: .custom-selector ...