实现效果：使用before和after就可以实现，代码量不多，长度颜色都可以自己调整
实现代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
*{
margin:0;
padding:0;
}
html,body{
width:100%;
height:100%;
background:#040d32;
}
.border-box{
position: relative;
margin:300px auto;
width:400px;
height:300px;
background: rgba(1, 19, 67, 0.8);
border: 2px solid #00a1ff;
border-radius: 8px;
}
.border-box::before {
position: absolute;
top: -2px;
bottom: -2px;
left: 30px;
width: calc(100% - 60px);
content: "";
border-top: 2px solid #016886;
border-bottom: 2px solid #016886;
z-index: 0;
}
.border-box::after {
position: absolute;
top: 30px;
right: -2px;
left: -2px;
height: calc(100% - 60px);
content: "";
border-right: 2px solid #016886;
border-left: 2px solid #016886;
z-index: 0;
}
.border-box p{
line-height:100px;
text-align: center;
color:#00a1ff;
}
</style>
</head>
<body>
<div class="border-box">
<p>css实现科技感边框</p>
</div>
</body>
</html>