代码如下:

.devise-welcome-triangle{
border-right: #ccc 8px solid !important;
border-top: transparent 6px solid !important;
border-bottom: transparent 6px solid !important;
margin-left: -8px;
float: left;
z-index: 1000;
position: relative;
margin-top: 12px;
width: 0px;
height: 0px;
}
.devise-welcome-triangle div{
border-right: #EEEEEE 8px solid !important;
border-top: transparent 6px solid !important;
border-bottom: transparent 6px solid !important;
float: left;
z-index: 1100;
position: relative;
width: 0px;
margin-left: 4px;
margin-top: -6px;
height: 0px;
}