Relevant Dropdowns: Polyfill for Datalist
The list attribute / datalist element of HTML5 forms is pretty cool. As you type in a text input, it shows you a dropdown menu of choices you can pick from. Or you can type in whatever you want. The list attribute alone doesn't lock you into any specific value. In that way, it's a bit like a group of radio buttons with an "other" type-in option.
At the beginning of this month I wrote a post accompanied by five demo pages that showed that CSS3 transitions could be triggered with a number of different events/states in CSS. That alone should help you see how these types of simple animations work. But let’s take this a bit further.