I´m in a novice user of html and css and there´s something I am cannot get to work. I have some images that should be positioned at at certain coordinates. I have done this in css like this:

#trappediagram {
position:absolute;
bottom: 300px;
left: 175px;
}

For some reason, this image moves when I refresh my internet browser while scrolling down. Can anyone help me on this?