设置蓝色轮廓的Bootstrap 4按钮
要设置蓝色轮廓的Bootstrap4按钮，请使用.btn-outline-primary类。
将蓝色轮廓添加到按钮-
<button type="button" class="btn btn-outline-primary"> Blue outline </button>
您可以尝试运行以下代码以在Bootstrap中实现btn-outline-primary类-
示例
<!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>
</head>
<body>
<div class="container">
<h4>Bootstrap 4</h4>
<p>You can see blue outline below:</p>
<button type="button" class="btn btn-outline-primary">Blue outline</button>
</div>
</body>
</html>