question about input css?

I use <input>,it will display a border around input text. Now I want to use css to get rid of left,right and top line,and only leave bottom line of input text,how to realize it with css?

Thanks

border-top: none;
border-left: none;
border-right: none;
border-bottom: 1px solid;

You can use shorthand property also:

border:none;
border-bottom:1px solid #000;