这个问题分为两部分:

当你不知道模态的确切高度时,你如何将模态垂直地放置在中心? 是否有可能有模态居中,并有溢出:auto在模态体,但只有当模态超过屏幕高度?

我试过用这个:

.modal-dialog {
  height: 80% !important;
  padding-top:10%;
}

.modal-content {
  height: 100% !important;
  overflow:visible;
}

.modal-body {
  height: 80%;
  overflow: auto;
}

当内容远远大于垂直屏幕尺寸时,这给了我所需要的结果,但对于较小的模式内容,这几乎是不可用的。


当前回答

我写的最普遍的解。动态计算对话框高度。(下一步可能是重新计算窗口大小的对话框的高度。)

JSfiddle: http://jsfiddle.net/8Fvg9/3/

// initialise on document ready
jQuery(document).ready(function ($) {
    'use strict';

    // CENTERED MODALS
    // phase one - store every dialog's height
    $('.modal').each(function () {
        var t = $(this),
            d = t.find('.modal-dialog'),
            fadeClass = (t.is('.fade') ? 'fade' : '');
        // render dialog
        t.removeClass('fade')
            .addClass('invisible')
            .css('display', 'block');
        // read and store dialog height
        d.data('height', d.height());
        // hide dialog again
        t.css('display', '')
            .removeClass('invisible')
            .addClass(fadeClass);
    });
    // phase two - set margin-top on every dialog show
    $('.modal').on('show.bs.modal', function () {
        var t = $(this),
            d = t.find('.modal-dialog'),
            dh = d.data('height'),
            w = $(window).width(),
            h = $(window).height();
        // if it is desktop & dialog is lower than viewport
        // (set your own values)
        if (w > 380 && (dh + 60) < h) {
            d.css('margin-top', Math.round(0.96 * (h - dh) / 2));
        } else {
            d.css('margin-top', '');
        }
    });

});

其他回答

$('#myModal').on('shown.bs.modal', function() {
    var initModalHeight = $('#modal-dialog').outerHeight(); //give an id to .mobile-dialog
    var userScreenHeight = $(document).outerHeight();
    if (initModalHeight > userScreenHeight) {
        $('#modal-dialog').css('overflow', 'auto'); //set to overflow if no fit
    } else {
        $('#modal-dialog').css('margin-top', 
        (userScreenHeight / 2) - (initModalHeight/2)); //center it if it does fit
    }
});

在移动plantform中,它可能看起来有点不同,这是我的代码。

<div class="modal-container">
  <style>
  .modal-dialog{
    margin-top: 60%;
    width:80%;
    margin-left: 10%;
    margin-right: 10%;
    margin-bottom: 100%
  }
  @media screen and (orientation:landscape){
    .modal-dialog{
      margin-top: 70;
      width:80%;
      margin-left: 10%;
      margin-right: 10%;
      margin-bottom: 100%
    }
  }
  .modal-body{
    text-align: center;
  }
  .modal-body p{
    margin:14px 0px;
    font-size: 110%;
  }
  .modal-content{
    border-radius: 10px;
  }
  .modal-footer{
    padding:0px;
  }
  .modal-footer a{
    padding: 15px;
  }
  .modal-footer a:nth-child(1){
    border-radius: 0px 0px 0px 10px;
  }
  .modal-footer a:nth-child(2){
    border-radius: 0px 0px 10px 0px;
  }
  </style>
  <h2>Basic Modal Example</h2>
  <div data-toggle="modal" data-target="#myModal">Div for modal</div>
    <div class="modal fade" id="myModal" role="dialog">
      <div class="modal-dialog">
        <div class="modal-content">
          <div class="modal-body">
            <p>确定要取消本次订单嘛?</p>
          </div>
          <div class="modal-footer">
            <div class="btn-group btn-group-justified">
              <a href="#" class="btn btn-default" data-dismiss="modal">取消</a>
              <a href="#" class="btn btn-default" data-dismiss="modal">确定</a>
            </div>
          </div>
        </div>
      </div>
    </div>
</div>

将模式中心设置为屏幕

.modal {
  text-align: center;
  padding: 0!important;
}
.modal:before {
  content: '';
  display: inline-block;
  height: 100%;
  vertical-align: middle;
  margin-right: -4px;
}
.modal-dialog {
  display: inline-block;
  text-align: left;
  vertical-align: middle;
}

试试这样做:

.popup__overlay {
    position: fixed;
    left:  0;
    top:  0;
    width: 100%;
    height: 100%;
    z-index: 999;
    text-align: center
    }
.popup {
    display: inline-block;
    vertical-align: middle
    } 

您可能想要查看这个div绝对居中的方法集合:http://codepen.io/shshaw/full/gEiDt