Opera is helping people
In the old days, people used to do things like laying out their web sites inside giant tables, using the different table cells to position their graphics, text etc (not what tables were intended for, adds superflous markup to the page). They used to use invisible images called spacer GIFs to fine tune positioning of page elements (not what images are intended for, add superfluous markup and images to the page).
So go and
check it out, it sure is a great resource and will get better.
updated 23th september 2016