how to make div Tag is 100px less than 100%

Introduction:

Here i will explain how to make div Tag is 100px less than 100%.

description:

Most of DIV tag default size is 100% but we can create any pixel in div tag size. Here some example

Example:

div {
    width: 100%;
    width: -webkit-calc(100% - 100px);
    width: -moz-calc(100% - 100px);
    width: calc(100% - 100px);
}