keeping div boxes in the same place, i need some help Options

[rewop]

all my codes after a some amount of time alter so that all the boxes move up, to the left; or out of position. also it tends to look different on other people's computers.

could it be that i am defining positions with percents?

here's an example of one code

CODE

.div1 {
background-color:black; color:white;
border:2px solid; border-color:silver;
width:789px; height:1000px; overflow:inherit;
position:absolute; z-index:2; left:50%; top:0%;
margin-left:-394px; margin-top:150px; text-align:center;
visibility:visible;}
marquee { z-index:8; }

[rewop]

yea thats is the funny thing...its all right but..somehow it tends to move everynow and then.

do you think im better coding from scratch again in hope that it will fix the glitch?