Javascript - Changing border-width without moving surrounding elements.

Answer 1

Decrease the width by two times the border increase ..

 $('.Size').hover(
  function() {
      var width = parseInt($(this).css('width'));
      $(this).css('borderWidth', '5px').css({width:width-8});
  },
  function() {
      var width = parseInt($(this).css('width'));
    $(this).css('borderWidth', '1px').css({width:width+8});
  })

have a look at http://jsfiddle.net/rBrZL/