html 元素四角边框

html-element-corner-border.scss

&:before {
    content: "";
    width: 100%;
    height: 10px;
    position: absolute;
    top: 0;
    left: 0;
    background: linear-gradient(to left, #7BBBDC, #7BBBDC) left top no-repeat, linear-gradient(to bottom, #7BBBDC, #7BBBDC) left top no-repeat, linear-gradient(to left, #7BBBDC, #7BBBDC) right top no-repeat, linear-gradient(to bottom, #7BBBDC, #7BBBDC) right top no-repeat;
    background-size: 2px 10px, 10px 2px, 2px 10px, 10px 2px;
}

&:after {
  content: "";
  width: 100%;
  height: 10px;
  position: absolute;
  bottom: 0;
  left: 0;
  background: linear-gradient(to left, #7bbbdc, #7bbbdc) left bottom no-repeat,
    linear-gradient(to bottom, #7bbbdc, #7bbbdc) left bottom no-repeat,
    linear-gradient(to left, #7bbbdc, #7bbbdc) right bottom no-repeat,
    linear-gradient(to bottom, #7bbbdc, #7bbbdc) right bottom no-repeat;
  background-size: 2px 10px, 10px 2px, 2px 10px, 10px 2px;
}