how to applay Multiple classes to one html element

this is very simile but many of us don't know this. if you know it leave it :)

.red {color: red;}
.bold {font-weight: strong;}

This text will be red yet also bold!

how to Position an element center screen

here is a simple css code with this you can simply Position any html element to screen center

#popup { height:400px; width:500px; position: absolute; top: 50%; left: 50%;}
#popup{ margin-top: -200px; margin-left: -250px;}

How to remove the dotted border from image hyperlink

Many times, when you click on someone’s logo, you see that little dotted border around the image it very boring. here is a simple css solution for that.

a { outline: none; }