CSS3 圆形#css3-circle{ width: 150px; height: 150px; border-radius: 50%; background-color: #232323;}CSS3 椭圆形#css3-elipse{ width: 200px; height: 100px; border-radius: 50%; background-color: #232323;}CSS3 三角形#css3-triangle{ width: 0; height: 0; border-left: 100px solid transparent; border-right: 100px so