Bootstrap 4模态中心内容

Question

有人可以解释如何在Bootstrap 4模式中水平居中标题。

我已经尝试过text-center ， mx-auto和ml-0 / mr-0但它们似乎不起作用。

这是一个小提琴的链接 。

代码如下;

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

Answer 1

modal-header是display：flex，因此以'内容（如modal-title ）为中心的方式不同。 您可以使用mx-auto但是居中相对于关闭按钮，因此它不是完全居中。

一个选项是使标题显示：块（ d-block ）并使用text-center 。

https://jsfiddle.net/44v0b25k/

<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header d-block">
        <button type="button" class="close float-right" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
        <h5 class="modal-title text-center" id="exampleModalLabel">Modal title</h5>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

另一种选择是在modal-title上使用w-100 ，使其全宽， text-center也可以使用。

<div class="modal-header">
     <h5 class="modal-title w-100 text-center" id="exampleModalLabel">Modal title</h5>
     <button type="button" class="close" data-dismiss="modal" aria-label="Close">
        <span aria-hidden="true">&times;</span>
     </button>
</div>

https://jsfiddle.net/306ob2e5/

Answer 2

下面我添加了text-center d-block到标题， d-inline-block到标题。

问题是标题是flex，其中包含了对齐内容空间 - 将标题推向左侧。

 <!-- Button trigger modal --> <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal"> Launch demo modal </button> <!-- Modal --> <div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-header text-center d-block"> <h5 class="modal-title d-inline-block" id="exampleModalLabel">Modal title</h5> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">&times;</span> </button> </div> <div class="modal-body"> ... </div> <div class="modal-footer"> <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button> <button type="button" class="btn btn-primary">Save changes</button> </div> </div> </div> </div> 

示例Bootply

Answer 3

只需将CSS应用于modal-title类，例如：

.modal-title {
    text-align: center;
    width: 100%;
}

示例： https ： //jsfiddle.net/vxsw0xsy/