Images without width / height

It is considered good form to always indicate for the images we use on the page, their length and width. Often, such pictures, if we don’t specify their sizes, can rock our layout during the download.
To make it more explicit during development, where we missed images without specifying sizes, the guys from 37Signals offered a small but extremely useful snippet:

img:not([width]):not([height]) { border: 2px solid red !important; } 

Now all the pictures for which we did not specify the size - will be highlighted with a red frame, and miss them will be much more difficult.

Original article