Absolute vs Fixed Positioning

Question

I have a custom dialog box which is shown when I click a button. After the dialog box is shown I show a overlay. The height and width of the overlay is 100% x 100%.

Answer 1

position: absolute takes the element out of line with the document. so the height is that of the viewport, and the top,left values are static. Change this to position: fixed and you will see better results.