This text has a pink background, a thin, blue left border and a thick purple bottom border. CSS lets you specify lots of things if you want.
<style type="text/css"> p { border-width: thin ; width: 70% ; margin-left: 20% ; background: pink ; padding: 2em ; border-left: solid ; border-right: none ; border-top: none ; border-bottom: solid ; border-left-width: thin ; border-bottom-width: thick ; border-left-color: blue ; border-bottom-color: purple ; font-size: 200% ; } </style>