Can't center top down with Bootstrap in HTML-CodePudding

I wrote a code like this:

    .box {
        background-color: red;
    }
    
    .container {
        height: 50vh;
        background-color: blue;
    }

    <!DOCTYPE html>
    <html lang="en">

    <head>
        <meta charset="UTF-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet"
            integrity="sha384-GLhlTQ8iRABdZLl6O3oVMWSktQOp6b7In1Zl3/Jr59b6EGGoI1aFkw7cmDA6j6gD" crossorigin="anonymous">
        <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"
            integrity="sha384-w76AqPfDkMBDXo30jS1Sgez6pr3x5MlQ1ZAGC nuZB EYdgRZgiwxhTBTkF7CXvN"
            crossorigin="anonymous"></script>
        <link rel="stylesheet" href="style.css">
        <title>Document</title>
    </head>

    <body>
        <div style="height: 250px; background-color: blue;">
            <div >
                <div >
                    <div >1</div>
                </div>
                <div >
                    <div >1</div>
                </div>
            </div>
        </div>
    </body>

    </html>

My goal is to center it from top to bottom. So like this:

enter image description here

The code I wrote is not working for some reason. I read the documentation but couldn't find a solution. I wonder why the code boxes I wrote are not centered?

I tried the sample codes in the documents.

CodePudding user response：

Set your flex div to a height of 100% and set justify-content to center

.box {
  background-color: red;
}

.container {
  height: 50vh;
  background-color: blue;
}

<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-GLhlTQ8iRABdZLl6O3oVMWSktQOp6b7In1Zl3/Jr59b6EGGoI1aFkw7cmDA6j6gD" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-w76AqPfDkMBDXo30jS1Sgez6pr3x5MlQ1ZAGC nuZB EYdgRZgiwxhTBTkF7CXvN" crossorigin="anonymous"></script>
<div style="height: 250px; background-color: blue;">
  <div >
    <div >
      <div >1</div>
    </div>
    <div >
      <div >1</div>
    </div>
  </div>
</div>

CodePudding user response：

SioGabx probably has the best answer, but as an alternative, you could always use table tags to accomplish a similar look.

        <table border="1" style="background-color: blue;">
            <tr>
                <td valign="middle" style="height: 500px;">
                    <div style="background-color: red;">Box</div>
                </td>
            </tr>
        </table>

CodePudding user response：

You could accomplish this by setting your parent div, the blue one, to display: flex, flex-direction: column, and justify-content: center. You can accomplish this all with built in bootstrap utility classes. Your code would look like this.

<div  style="height: 250px; background-color: blue;">
            <div >
                <div >
                    <div >1</div>
                </div>
                <div >
                    <div >1</div>
                </div>
            </div>
        </div>

Note: I've also changed your "justify-content-start" to "justify-content-center"

Here is how this looks, finished: screenshot