如何摆脱边框的右侧和左侧，而又不脱离顶部和底部？

Question

"How do you get rid of the right and left sides of a border without getting rid of the top and bottom sides?" ^Title says it all.

Answer 1

border: none;
border-bottom, border-top: 1px solid black;

or whatever thickness and color you want.

or the other way round:

border-left, border-right: none;

Answer 2

Use the following format where you specify all property values:

.dom {
    border-width:10px 0px 10px 0px;
}