How can I set a css border on one side only?

Question

For a given div I would like to only display a border on the left, right, top, or bottom side.

Currently I have the following, which puts a border on all s

Answer 1

#testdiv {
   border-left: 1px solid;
}

See the MDN documentation on border.

Answer 2

Try like this

#testdiv{
  border-left:1px solid;

}

Answer 3

#testDiv{
    /* set green border independently on each side */
    border-left: solid green 2px;
    border-right: solid green 2px;
    border-bottom: solid green 2px;
    border-top: solid green 2px;
}

Answer 4

    div{
    border-left:solid red 3px;
    border-right:solid violet 4px;
    border-top:solid blue 4px;
    border-bottom:solid green 4px;
    background:grey;
    width:100px; height:50px
}

DEMO

Answer 5

You can specify border separately for all borders, for example:

#testdiv{
  border-left: 1px solid #000;
  border-right: 2px solid #FF0;
}

You can also specify the look of the border, and use separate style for the top, right, bottom and left borders. for example:

#testdiv{
  border: 1px #000;
  border-style: none solid none solid;
}

Answer 6

If you want to set 4 sides separately use:

border-width: 1px 2em 5px 0; /* top right bottom left */
border-style: solid dotted inset double;
border-color: #f00 #0f0 #00f #ff0;