1.bootstrap中文官網
2.步驟
2.1復制基本模板代碼
https://v3.bootcss.com/getting-started/#template
2.2復制頁頭代碼
https://v3.bootcss.com/components/#page-header
2.3創建中間登錄框部分div和底部div
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>登錄界面
</title>
<!-- Bootstrap -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<!-- 標題 -->
<div class="page-header">
<h1>XXXX信息系統登錄界面</h1>
</div>
<!-- 中間登錄框 -->
<div class="container-fluid">
<div class="row">
</div>
</div>
<!-- 頁腳 -->
<div class="footer">
<p>©版權所有：XXXXX學院XX市XX大道XXX號</p>
<p>郵編：530001聯系郵箱：xxxxxxx@163.com</p>
</div>
</div>
<!-- jQuery (Bootstrap 的所有 JavaScript 插件都依賴 jQuery，所以必須放在前邊) -->
<script src="https://cdn.jsdelivr.net/npm/jquery@1.12.4/dist/jquery.min.js"></script>
<!-- 加載 Bootstrap 的所有 JavaScript 插件。你也可以根據需要只加載單個插件。 -->
<script src="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js"></script>
</body>
</html>
2.4復制水平排列表單到中間登錄框部分div
https://v3.bootcss.com/css/#forms-horizontal
2.5 調整樣式（一個Html標簽可以應用多個類樣式，中間用空格隔開）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>登錄界面
</title>
<!-- Bootstrap -->
<script src="js/jquery-3.4.1.js"></script>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
<style>
.bg{
height: 600px;
background-image:url(/images/bg.jpg);
background-size:cover;
}
.form{
padding: 40px;
margin-top: 175px;
background: rgba(255,255,255,0.2);
}
.footer{
height: 60px;
padding-top:20px;
font-size: 14px;
font-weight: bold;
text-align: center;
}
</style>
</head>
<body>
<div class="page-header">
<h1>XXXX信息系統登錄界面</h1>
</div>
<div class="container-fluid">
<div class="row bg">
<div class="col-md-offset-6 col-md-4 col-sm-offset-3 col-sm-7 col-xs-offset-2 col-xs-8 col-lg-offset-6 col-lg-3 form">
<form class="form-horizontal" id="loginForm">
<div class="form-group">
<label for="username" class="col-sm-4 control-label">用戶名</label>
<div class="col-sm-8">
<input type="text" class="form-control" id="username" placeholder="請輸入用戶名">
</div>
</div>
<div class="form-group">
<label for="password" class="col-sm-4 control-label">密碼</label>
<div class="col-sm-8">
<input type="password" class="form-control" id="password" placeholder="請輸入密碼">
</div>
</div>
<div class="form-group">
<label for="validateCode" class="col-sm-4 control-label">驗證碼</label>
<div class="col-sm-4">
<input type="text" class="form-control" id="validateCode" placeholder="請輸入驗證碼" >
</div>
<div class="col-sm-4">
<img src="images/yzm.jpg" alt="" width="75px" height="35px">
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<div class="checkbox">
<label>
<input type="checkbox">記住我
</label>
</div>
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<button type="button" id="submitBtn" class="btn btn-success" style="width: 50%;">登錄</button>
</div>
</div>
</form>
<span style="color: red;" id="tip"></span>
</div>
</div>
<div class="footer">
<p>©版權所有：XXXXX學院XX市XX大道XXX號</p>
<p>郵編：530001聯系郵箱：xxxxxxx@163.com</p>
</div>
</div>
<!-- jQuery (Bootstrap 的所有 JavaScript 插件都依賴 jQuery，所以必須放在前邊) -->
<script src="https://cdn.jsdelivr.net/npm/jquery@1.12.4/dist/jquery.min.js"></script>
<!-- 加載 Bootstrap 的所有 JavaScript 插件。你也可以根據需要只加載單個插件。 -->
<script src="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js"></script>
</body>
</html>
3.運行效果圖（一個簡陋的登錄界面）
