在Bootstrap中使用border-0类消除元素的所有边界，如下所示-
<div class="mystyle border border-0"> No border </div>
我们还在上面设置了CSS样式-
.mystyle {
width: 120px;
height: 100px;
margin: 10px;
background: gray;
}您可以尝试运行以下代码以实现border-0类-
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="https://cdn.staticfile.org/jquery/3.3.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<style>
.mystyle {
width: 120px;
height: 100px;
margin: 10px;
background: gray;
}
</style>
</head>
<body>
<div class="container">
<h4>Two Rectangles</h4>
<div class="mystyle border border-success">orange border</div>
<div class="mystyle border border-0">No border</div>
</div>
</body>
</html>