Bootstrap 4选择样式

Question

在我的Bootstrap v4表单中，我增加了form-control元素的填充，但我注意到此填充未应用于select元素。

 .form-control { padding: .6rem .8rem !important; border: 2px solid #ced4da !important; transition: none !important; } 

 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.3/css/bootstrap.min.css" integrity="sha384-Zug+QiDoJOrZ5t4lssLdxGhVrurbmBWopoEl+M6BdEfwnCJZtKxi1KgxUyJq13dy" crossorigin="anonymous"> <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.3/js/bootstrap.min.js" integrity="sha384-a5N7Y/aK3qNeh15eJKGWxsqtnX/wWdSZSKp+81YjTmS15nvnvxKHuzaWwXHDli+4" crossorigin="anonymous"></script> <div class="container-fluid"> <div class="row"> <div class="col-md-12"> <form> <div class="form-row"> <div class="form-group col-md-6"> <label for="inputEmail4">Email</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Email"> </div> <div class="form-group col-md-6"> <label for="inputPassword4">Password</label> <input type="password" class="form-control" id="inputPassword4" placeholder="Password"> </div> <div class="form-group col-md-6"> <label for="inputState">State</label> <select id="inputState" class="form-control"> <option selected>Choose...</option> <option>...</option> </select> </div> </div> <button type="submit" class="btn btn-primary">Sign in</button> </form> </div> </div> </div> 

不幸的是，我无法构建Bootstrap的自定义版本，因此我必须通过应用纯CSS来覆盖行为。

我创建了一个演示问题的JSFiddle 。

如何在Bootstrap v4表单中将填充正确地应用到select元素？

Answer 1

您尝试将填充应用于Bootstrap 4 form-control元素的方式不正确。 因为Bootstrap 4具有专门设计用于满足您所有间距需求的本机类。 并且还因为这样的css hack可以（而且经常）导致导致需要更多css hack来解决由原始css hack引起的问题的问题。

因此，请使用p-*和m-*类为元素应用间距，并避免不必要的破坏。

有关Bootstrap 4间隔实用程序的更多信息：

https://getbootstrap.com/docs/4.0/utilities/spacing/

编辑：

要解决自定义css的问题，您需要添加以下规则：

 select.form-control{ height: auto !important; padding: .6rem .8rem calc(.6rem + 1px) .8rem !important; } 

这是完整的有效代码段（单击“运行代码段”并展开到全屏以进行左右比较）：

 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"> <style> .form-control { padding: .6rem .8rem !important; border: 2px solid #ced4da !important; transition: none !important; } select.form-control{ height: auto !important; padding: .6rem .8rem calc(.6rem + 1px) .8rem !important; } </style> <div class="container-fluid"> <div class="row"> <div class="col-md-12"> <form> <div class="form-row"> <div class="form-group col-md-6"> <label for="inputEmail4">Email</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Email"> </div> <div class="form-group col-md-6"> <label for="inputPassword4">Password</label> <input type="password" class="form-control" id="inputPassword4" placeholder="Password"> </div> <div class="form-group col-md-6"> <label for="inputState">State</label> <select id="inputState" class="form-control"> <option selected>Choose...</option> <option>...</option> </select> </div> <div class="form-group col-md-6"> <label for="inputEmail4">Test</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Choose... (normal input for comparison)"> </div> </div> <button type="submit" class="btn btn-primary">Sign in</button> </form> </div> </div> </div> 

编辑2：

更好的解决方案是使用.custom-select因为普通的选择本质上是越野车。 custom-select是专门为易于样式设计的，因为普通选择是如此之多（没有太多可做的事情）。

这是一个带有自定义选择的代码段，用于比较：

 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"> <style> .form-control { padding: .6rem .8rem !important; border: 2px solid #ced4da !important; transition: none !important; } select.form-control{ height: auto !important; padding: .6rem .8rem calc(.6rem + 1px) .8rem !important; } .custom-select { height: auto !important; padding: .6rem .8rem !important; border: 2px solid #ced4da !important; transition: none !important; } </style> <div class="container-fluid"> <div class="row"> <div class="col-md-12"> <form> <div class="form-row"> <div class="form-group col-md-6"> <label for="inputEmail4">Email</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Email"> </div> <div class="form-group col-md-6"> <label for="inputPassword4">Password</label> <input type="password" class="form-control" id="inputPassword4" placeholder="Password"> </div> <div class="form-group col-md-6"> <label for="inputState">State</label> <select id="inputState" class="form-control"> <option selected>Choose...</option> <option>...</option> </select> </div> <div class="form-group col-md-6"> <label for="inputEmail4">Test</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Choose... (normal input for comparison)"> </div> <div class="form-group col-md-6"> <label for="inputState">custom-select:</label> <div class="input-group"> <select class="custom-select" id="inputGroupSelect04"> <option selected>Choose... (custom-select)</option> <option value="1">One</option> <option value="2">Two</option> <option value="3">Three</option> </select> </div> </div> <div class="form-group col-md-6"> <label for="inputEmail4">Test</label> <input type="email" class="form-control" id="inputEmail4" placeholder="Choose... (normal input for comparison)"> </div> </div> <button type="submit" class="btn btn-primary">Sign in</button> </form> </div> </div> </div> 

Answer 2

填充方式正确，但是您必须更改高度

select.form-control{
  height:auto !important;
}

https://jsfiddle.net/oon0pmup/3/

Answer 3

在CSS选择器上使用更多特性来覆盖Bootstrap高度：

select.form-control:not([size]):not([multiple]) {
    height: initial;
}

选择的高度将与文本输入的高度相同（假设所有输入均使用相同的填充，边框等）。

https://www.codeply.com/go/rJKOyAx1QA