给div来个酷炫的四角边框—linear-gradient

.border1 {
    background: linear-gradient(to left, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) left top no-repeat, 
 linear-gradient(to bottom, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) left top no-repeat, 
 linear-gradient(to left, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) right top no-repeat,
 linear-gradient(to bottom, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) right top no-repeat, 
 linear-gradient(to left, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) left bottom no-repeat,
 linear-gradient(to bottom, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) left bottom no-repeat,
 linear-gradient(to left, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) right bottom no-repeat,
 linear-gradient(to left, rgba(51, 51, 51, 1), rgba(51, 51, 51, 1)) right bottom no-repeat;
   /*设置大小*/
    background-size: 0.15rem 0.6rem, 0.6rem 0.15rem, 0.15rem 0.6rem, 0.6rem 0.15rem;
}

.border2 {
	margin: 300px auto;
	width: 200px;
	height: 100px;
	background: linear-gradient(blue, blue) left top,
		linear-gradient(blue, blue) left top,
		linear-gradient(blue, blue) right top,
		linear-gradient(blue, blue) right top,
		linear-gradient(blue, blue) left bottom,
		linear-gradient(blue, blue) left bottom,
		linear-gradient(blue, blue) right bottom,
		linear-gradient(blue, blue) right bottom;
	background-repeat: no-repeat;
	background-size: 1px 24px, 24px 1px;
}

.card{
  background: radial-gradient(circle at center center, rgba(23, 48, 78, 1), rgba(20, 37, 63, 1)),
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) left top,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) left top,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) right top,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) right top,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) left bottom,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) left bottom,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) right bottom,
  linear-gradient(rgba(179,224,255,0.62), rgba(179,224,255,0.62)) right bottom,
  linear-gradient(rgba(56, 144, 184, 0.60), rgba(56, 144, 184, 0.60)) top,
  linear-gradient(rgba(26, 87, 130, 0.60), rgba(26, 87, 130, 0.60)) bottom,
  linear-gradient(rgba(56, 144, 184, 0.60), rgba(219, 240, 255, 0.80), rgba(26, 87, 130, 0.60)) left,
  linear-gradient(rgba(56, 144, 184, 0.60), rgba(219, 240, 255, 0.80), rgba(26, 87, 130, 0.60)) right;
  background-repeat: no-repeat;
  background-position: 1px 1px, 0px 0px, 0px 0px, 0px 100%, 0px 100%, 100% 0px, 100% 0px, 100% 100%, 100% 100%, 0px 0px, 0px 100%, 0px 100%, 100% 100%;
  background-size: calc(100% - 2px) calc(100% - 2px), 1px 10px, 10px 1px, 1px 10px, 10px 1px, 1px 10px, 10px 1px, 1px 10px, 10px 1px, 100% 1px, 100% 1px, 1px 100%, 1px 100%;
}