Pipette allows you to instantly grab the colour of any pixel on your screen and copy it in hex format, as used in CSS files, or graphic softwares, such as Adobe Photoshop.
Step 1: Download Pippette here.
Step 2: Unzip it and run the application. You should have something like this:
Step 3: Click on the Pipette button then drag it on the color you want to get in your screen. The color you get will appear in the color list.
Step 4: You may now copy and paste the color HEX value to your CSS file or paint software. :)