<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="Hotel.WebForm1" EnableEventValidation="false" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <link rel="stylesheet" href="Assets/Libraries/Bootstrap/css/bootstrap.min.css" /> <style> body{ background-image:url(../Assets/Images/hotel4.jpg); background-size:cover; } .container-fluid{ opacity:0.9; } </style> </head> <body> <form id="form1" runat="server" > <div> <div class="container-fluid"> <div class="row" style="height:200px"></div> <div class="row"> <div class="col-md-4"></div> <div class="col-md-4 bg-light rounded-3"> <h1 class="text-text-success text-center">皇家理工度假酒店</h1> <form> <div class="mb-3"> <label for="UserTb" class="form-label">用户名</label> <input type="text" class="form-control" id="UserTb" runat="server" required="required"> </div> <div class="mb-3"> <label for="PasswordTb" class="form-label">密码</label> <input type="password" class="form-control" id="PasswordTb" runat="server" required="required"> </div> <div class="mb-3"> <label id="ErrMsg" class="text-danger" runat="server"></label> <input type="radio" id="AdminCb" runat="server" name="Role"><label class="text-success">管理员</label> <input type="radio" id="UserCb" runat="server" name="Role"><label class="text-success">用户</label> </div> <div class="d-grid"> <asp:Button ID="LoginBtn" runat="server" Text="登陆" class="btn btn-success btn-block" OnClick="LoginBtn_Click" /> </div> <br /> </form> </div> <div class="col-md-4"></div> </div> </div> </div> </form> </body> </html>我在form中添加了align=center属性但是删除后却依旧运行了原先配置