答案：使用CSSmargin-top属性
默认情况下，Bootstrap模态窗口与页面顶部对齐，并留有一些空白。但是您可以使用一个简单的JavaScript技巧将其垂直对齐在页面中间，如下面的示例所述。此解决方案将动态调整模式的对齐方式，即使用户调整浏览器窗口的大小，也始终将其保持在页面中央。
例试试这个代码»
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Vertical Center Alignment of Bootstrap Modal Dialog</title>
<link rel="stylesheet" href="css/bootstrap.min.css">
<script src="js/jquery-3.5.1.min.js"></script>
<script src="js/bootstrap.min.js"></script>
<script>
$(document).ready(function(){
function alignModal(){
var modalDialog = $(this).find(".modal-dialog");
// Applying the top margin on modal to align it vertically center
modalDialog.css("margin-top", Math.max(0, ($(window).height() - modalDialog.height()) / 2));
}
// Align modal when it is displayed
$(".modal").on("shown.bs.modal", alignModal);
// Align modal when user resize the window
$(window).on("resize", function(){
$(".modal:visible").each(alignModal);
});
});
</script>
</head>
<body>
<div class="m-4">
<!-- Button HTML (to Trigger Modal) -->
<a href="#myModal" class="btn btn-primary btn-lg" data-toggle="modal">Launch Demo Modal</a>
<!-- Modal HTML -->
<div id="myModal" class="modal">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title">Confirmation</h5>
<button type="button" class="close" data-dismiss="modal">×</button>
</div>
<div class="modal-body">
<p>Do you want to save changes you made to document before closing?</p>
<p class="text-warning"><small>If you don't save, your changes will be lost.</small></p>
</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>
</div>
</body>
</html>
如需转载，请注明文章出处和来源网址：http://www.divcss5.com/html/h61189.shtml
