ml-auto
类起作用,您只需要向父元素添加 d-flex
类(显示:flex),如下所示:
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<div class="card-header bg-info text-white d-flex">
<a href="#" class="text-white"><i class="fa-th"></i> Media Library</a>
<a href="#" class="text-white ml-auto">Add Media</a>
</div>
<a href="#" class="text-white" style="text-align: right;"><i class="fa-th"></i> Media Library</a>
<div class="card-header bg-info text-white" style="text-align:right">
<a href="#" class="text-white"><i class="fa-th"></i> Media Library</a>
</div>
<div class="card-header bg-info text-white text-right">
<a href="#" class="text-white"><i class="fa-th"></i> Media Library</a>
</div>