正三角:
.upTriangle{
width: 0;
height: 0;
border-top: 4px solid #375CC0;
border-left: 4px solid #375CC0;
border-right: 4px solid #375CC0;
border-bottom: 4px solid #ffffff;
}
倒三角:
.downTriangel{
width: 0;
height: 0;
border-top: 4px solid #ffffff;
border-left: 4px solid #375CC0;
border-right: 4px solid #375CC0;
border-bottom: 4px solid #375CC0;
}