Use of Calc

In general, an element node uses fixed positioning absolute and fixed positioning to fix, encounter a problem, if set 100%, at this time you set the Padding,border,margin to him, it will be full

Specific conditions such as:

CSS3 provides a property method for Calc;

. box {Width:calc (Value of 100%-padding value-border-width)}

Of course, this is the CSS3 method, in the actual project to add a prefix

You'll get a similar effect

Specific examples do not give, because relatively simple, reference site: http://www.w3cplus.com/css3/how-to-use-css3-calc-function.html

Use of Calc