1×1 span or div?

Hello,
I wish to have a marker on my application to assist in targeting a screen capture.
The idea is to place a 1×1 span or div in the corners but these codes always produce something 1wX2h.

<span id=”mark1″ style=”position:absolute;top:-1;left:0;width:1px;height:1px;z-index:30;background:#ff0000;font-size:1px”></span>
<span id=”mark2″ style=”font-size:1px;background:#FF0000;position:absolute;top:’+(cropH-1)+’;left:’+(cropW-1)+’;z-index:30;height:1px;width:1px;”></span>

What can be done to get a true 1×1 marker? and, I can’t use an image because that would mean I’d have to completely rewrite a lot of script.

Also in #HTML _↴