html:定义一个div
<div class="item__content"></div>
css:样式
.item__content { position: relative; display: flex; flex-direction: column; justify-content: center; align-items: center; width: 80px; height: 80px; font-size: 40px; box-sizing: border-box; color: #18314F; background-color: #051a2d; background-image: url('../img/bg/border-line.png') ,url('../img/bg/border-line.png'),url('../img/bg/border-line.png'),url('../img/bg/border-line.png'); background-position: top left,top right,bottom left,bottom right; background-repeat: no-repeat, no-repeat, no-repeat, no-repeat; overflow: hidden; }
样式:(四个角的发光横线)