Normally in CSS whichever rule is specified last takes precedence. However if you use !important after a command then this CSS command will take precedence regardless of what appears after it.

This shows how the computed style of each node differs from the computed style of its parent. The root element, which has no parent, is instead compared against the root of a blank HTML document.

* create a new bookmark called "compute styles" in your firefox toolbar. Place the snippet code in the location field of your "compute styles". click the compute styles bookmark, then click an element on the page with the crosshairs.

Gives you the ability to dynamically include a CSS file at any time in your HTML page using Javascript.

Here's a library to manage CSS class names on DOM elements.

a simple css way to add shadow to tables and Divs

Using styles we can add scrollbars for large table where the space is a constraint

Not really a hack, but rather a workaround for layout problems with IE.
Conditional

Get computed Height of an HTML Element

Get computed Width of an HTML Element

Allows you to hide all elements on an HTML page by their tag name. Extremely handy in getting around the "Windowless Elements" problem in IE, which is a bug that puts certain elements, most commonly select boxes, on top of any other element, no matter what. As you can imagine, this causes real problems with DHTML drop-down menus and such like. This is the simplest and quickest fix I've come up with, I simply set this function to run alongside the drop-down and all of the select tags vanish before a menu drops, then I run the show function when the menu retracts.