How to add style to a tag as it is done in this website when we add tag

I have a text box with a auto complete list and the values are seperated by a ; How i can I add the css property just like in this website if we add tags, the tag come with a (x) for removing the tag, How can I implement that in my website. All i want is a 开发者_如何学编程(x) same as the tags that we add in Stackoverflow website.