A misunderstanding of font-size

Project there is a need to show a small dot, with the Font-awesome icon Library, conveniently set up a font-size:1px,chrome under the display no problem, ie, but how can not show, began to think that is empty span in IE bug, According to StackOverflow's answer modified the style still does not work, and finally inadvertently changed the font-size found normal display.

found that the original in Chrome under the default minimum is 12px, if there is no special processing, the value of less than 12px is not working, so even if set to 1px under Chrome Display or 12px size, but under IE will become too small or even see.

A misunderstanding of font-size