AS2 fluid layout content blurs

Hi, ive been trying the flash fluid approach for layout. I have a handle on the standard code as below; The issue Im having is the browser appears to place the container_mc off pixel resolution making it blur, as you scale the browser it can move into focus and out again, example I have sqr with 1px black border, this appears crisp, as the browser is resized the border goes grey and thicker say 2px, further resizing it will goes back into focus. This is not a good look, can someone advise, many thanks Paul

Stage.align = "TL";
Stage.scaleMode = "noScale";

background._width = Stage.width
background._height = Stage.height
background._x = 0
background._y = 0

container._x = Stage.width/2
container._y = Stage.height/2

sizeListener = new Object();
sizeListener.onResize = function() {

background._width = Stage.width
background._height = Stage.height
background._x = 0
background._y = 0

container._x = Stage.width/2
container._y = Stage.height/2

};

Stage.addListener(sizeListener);