CSS 反向转换和 select 前一个兄弟

Question

Bootstrap容器横向有两种形式。将鼠标悬停在 Form1 上将增加宽度并减少 form2 的宽度。但逆转并没有发生。有什么建议吗

<!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/3.3.7/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>

  <style>
  #row{
  background-color: lightblue;
  border-style: groove;
  }

  #form1{
  background-color: lightgreen;
  width: 50%;
  transition: width 0.75s ease;
  }

  #form1:hover{  
    width: 75%;
  }

  #form1:hover + #form2{
     width: 25%
   }

  #form2{
  background-color: orange;
  width: 50%;
  transition: width 0.75s ease;
  }  

  #form2:hover{
  width: 75%;  
  }

  #form2:hover ~ #form1{
     width: 25%
     }
  </style>


</head>
<body>

<div  class="container" >

  <div id="row" class="row" >
    <div id="form1" class="col-sm-6">
    <!-- form1 -->
        <form class="form-horizontal">
  <div class="form-group">
    <label class="control-label col-sm-2" for="email">Email:</label>
    <div class="col-sm-10">
      <input type="email" class="form-control" id="email" placeholder="Enter email">
    </div>
  </div>
  <div class="form-group">
    <label class="control-label col-sm-2" for="pwd">Password:</label>
    <div class="col-sm-10"> 
      <input type="password" class="form-control" id="pwd" placeholder="Enter password">
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-sm-offset-2 col-sm-10">
      <div class="checkbox">
        <label><input type="checkbox"> Remember me</label>
      </div>
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-sm-offset-2 col-sm-10">
      <button type="submit" class="btn btn-default">Submit</button>
    </div>
  </div>
</form>
    </div>
    <div id="form2" class="col-sm-6">
    <!-- form 2 -->
        <form class="form-horizontal">
  <div class="form-group">
    <label class="control-label col-sm-2" for="email">Email:</label>
    <div class="col-sm-10">
      <input type="email" class="form-control" id="email" placeholder="Enter email">
    </div>
  </div>
  <div class="form-group">
    <label class="control-label col-sm-2" for="pwd">Password:</label>
    <div class="col-sm-10"> 
      <input type="password" class="form-control" id="pwd" placeholder="Enter password">
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-sm-offset-2 col-sm-10">
      <div class="checkbox">
        <label><input type="checkbox"> Remember me</label>
      </div>
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-sm-offset-2 col-sm-10">
      <button type="submit" class="btn btn-default">Submit</button>
    </div>
  </div>
</form>
    </div>
</div>

</div>

</body>
</html>

请看下图。当悬停在绿色表格上时，表格从左到右移动，橙色表格减小宽度，绿色表格增加宽度，但是当悬停在橙色表格上时（反向）不会发生这种情况。

基本上我正在尝试实现像 THIS

这样的形式

Answer 1

您可以使用 flexbox 执行此操作。正如 Selva 所提到的，CSS 只能 select 下一个兄弟姐妹，而不是前一个兄弟姐妹。然而，使用 flexbox 这要容易得多：

.flexible{display: flex; flex-direction: row;}
#form1:hover{  
    width: 100%;
}
#form2:hover{  
    width: 100%;
}

https://jsfiddle.net/2g4krj0f/

Answer 2

纯CSS的解存在。您需要为选择器定义 css-rule，当悬停此表单而行悬停时选择 form1：#row:hover > #form1:not(:hover)

#row:hover > #form1:not(:hover){
     width: 25%;
}

http://www.codeply.com/go/0Q2gFDoc4y

查看片段（出于某种原因它在全屏模式下工作）：

#row{
  background-color: lightblue;
  border-style: groove;
  }

  #form1{
  background-color: lightgreen;
  width: 50%;
  transition: width 0.75s ease;
  }

  #form1:hover{  
    width: 75%;
  }

  #form1:hover + #form2{
     width: 25%
   }

  #form2{
  background-color: orange;
  width: 50%;
  transition: width 0.75s ease;
  }  

  #form2:hover{
  width: 75%;  
  }

  #row:hover > #form1:not(:hover){
     width: 25%;
     }

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<div  class="container" >

  <div id="row" class="row" >
    <div id="form1" class="col-xs-6">
    <!-- form1 -->
        <form class="form-horizontal">
  <div class="form-group">
    <label class="control-label col-xs-2" for="email">Email:</label>
    <div class="col-xs-10">
      <input type="email" class="form-control" id="email" placeholder="Enter email">
    </div>
  </div>
  <div class="form-group">
    <label class="control-label col-xs-2" for="pwd">Password:</label>
    <div class="col-xs-10"> 
      <input type="password" class="form-control" id="pwd" placeholder="Enter password">
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-xs-offset-2 col-xs-10">
      <div class="checkbox">
        <label><input type="checkbox"> Remember me</label>
      </div>
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-xs-offset-2 col-xs-10">
      <button type="submit" class="btn btn-default">Submit</button>
    </div>
  </div>
</form>
    </div>
    <div id="form2" class="col-xs-6">
    <!-- form 2 -->
        <form class="form-horizontal">
  <div class="form-group">
    <label class="control-label col-xs-2" for="email">Email:</label>
    <div class="col-xs-10">
      <input type="email" class="form-control" id="email" placeholder="Enter email">
    </div>
  </div>
  <div class="form-group">
    <label class="control-label col-xs-2" for="pwd">Password:</label>
    <div class="col-xs-10"> 
      <input type="password" class="form-control" id="pwd" placeholder="Enter password">
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-xs-offset-2 col-xs-10">
      <div class="checkbox">
        <label><input type="checkbox"> Remember me</label>
      </div>
    </div>
  </div>
  <div class="form-group"> 
    <div class="col-xs-offset-2 col-xs-10">
      <button type="submit" class="btn btn-default">Submit</button>
    </div>
  </div>
</form>
    </div>
</div>

</div>

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