Understanding :not

- [Instructor] The not sudo class is super, super handy. … It's going to allow you to select things … which do not meet a certain criteria. … For example, here on this web page, … you'll notice that we have two images. … One of these images is coded correctly in the HTML … in that it has its alt tag. … But the second image does not have its alt tag. … So let's say you're debugging your site … and you need to quickly identify which of your images … does not have an alt tag. … We can write a wonderful selector to do that. … In this case we're going to say, for all of the image tags, … let's not select those that are missing. … Basically we're saying the ones that do not have … the alt attribute. … We don't need to test for a value, … we just want to test for a presence or absence … of that alt attribute. … Five pixels, solid orange border around those images. … And if we go ahead and do that, … you'll see here we have selected the one kitten picture … that is indeed missing its alt tag. …