需要边框长度比容器小一些时，用div嵌套，但伪类在实现这个效果时很方便，只需要一个div就够了，另外调整padding和margin都不会很麻烦。

.box-container {

position: relative;

width: 90%;

color: #777;

}

.border-top {

background: #b4bcbf;

padding: 15px;

}

.border-top:before {

content: '';

position: absolute;

left: 42%;

top: 0;

bottom: auto;

right: auto;

height: 7px;

width: 50%;

background-color: #8796a9;

}

.border-left {

background: #dfdad6;

padding: 15px;

}

.border-left:before {

content: '';

position: absolute;

left: 0;

top: 6%;

bottom: auto;

right: auto;

height: 52%;

width: 5px;

background-color: #a89d9e;

}

.border-right {

background: #eee9c4;

padding: 15px;

}

.border-right:after {

content: '';

position: absolute;

left: auto;

top: auto;

bottom: 5px;

right: 0;

height: 52%;

width: 5px;

background-color: #f39c81;

}

.border-bottom {

background: #bcdc9d;

padding: 15px;

}

.border-bottom:after {

content: '';

position: absolute;

left: 18px;

top: auto;

bottom: 0;

right: auto;

height: 6px;

width: 105px;

background-color: #32b66b;

}

效果如下图：