About the size of the box

For example, design a box the size of 850px * 170px, solutions 2px front page is displayed by the browser of your quilt-level box extra 2px, it is more than clear

In the style tag inside to the top

*{

    box-sizing:border-box;

   Sizing-Box--moz: border-Box; / * Firefox * / Firefox

  Sizing-Box--webkit: border-Box; / * Safari * / browser compatibility issues

}