strange padding with max-height

I have this code : as you can see开发者_StackOverflow中文版 nothing of strange.

But, if I try to remove max-height:150px; from main_inside I see a small background red in the bottom of the image.

Why? It should be sized regard the max-height of the image class myImage....

Images put spaces below them in some browsers. The following will provide an easy fix.

.myImage{max-width:200px; border:0px; padding: 0px; display: block;}