max-width:100%on all images from the off can be a bad idea.
max-width:100%style declaration to all images when building a responsive site. Here's one reason why it might not always be a good idea.
Check in IE8, it seems the image above disappears.
So (in IE8) if you set
max-width: 100% on all images and an image happens to have a floated parent that doesn't have a specified width, the
max-width is interpreted as 0 because the parent is collapsed.