css - When 1 px border is added to div, Div size increases, Don't want to do that

Question

On click I am adding, 1px border to div, so Div size increases by 2px X 2px. I dont want to get div size increased. Is there any simple way to do so?

Messy Detailed Explanation
Actually I am adding DIVs with float:left (same size, like icons) to a container-div, so all stacks up one after another, and when (container-div width is 300px) no space left width-wise so child DIVs comes in next row, so its like catalog, but because of border only selected DIV size get increased, DIV under selected DIV goes to right and creates empty space below selected DIV.

EDIT:
Decreasing Height/Width on selection, but how to increase it back. Using some 3rd party framework, so don't have event when DIV loses selection..

Answer 1

This is also helpful in this scenario. it allows you to set borders without changing div width

textarea { 
  -webkit-box-sizing: border-box; /* Safari/Chrome, other WebKit */
  -moz-box-sizing: border-box;    /* Firefox, other Gecko */
  box-sizing: border-box;         /* Opera/IE 8+ */
}

Taken from http://css-tricks.com/box-sizing/