css控制边框虚线的长度或者间隔
border: 1px solid transparent;
background: linear-gradient(white,white) padding-box,
repeating-linear-gradient(-45deg,#ccc 0, #ccc 0.3em,white 0,white 0.45em);
border: 1px solid transparent;
background: linear-gradient(white,white) padding-box,
repeating-linear-gradient(-45deg,#ccc 0, #ccc 0.3em,white 0,white 0.45em);