代码如下所示：

#progressBox{

width: 300px;

height: 40px;

position: relative;

border: 1px solid #c8c8c8;

background: #fff;

}

#progressBar,#progressText{

position: absolute;

left: 0;

top: 0;

width: 100%;

line-height: 40px;

font-size: 18px;

text-align: center;

}

/*clip属性适使用于绝对定位*/

#progressBar{

z-index: 2;

background: #00a1f5;

/*第二个参数表示所切宽度*/

clip: rect(0px,0px,140px,0px);

color: white;

}

#progressText{

z-index: 1;

color: black;

}