<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>我是中国人</title>

        <!-- 新 Bootstrap 核心 CSS 文件 -->
        <link href="css/bootstrap.min.css" rel="stylesheet">

        <!-- 最新的 Bootstrap 核心 JavaScript 文件 -->
        <script src="js/bootstrap.min.js"></script>

        <script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script>
    </head>
    <body>
        <div id="" class="container">
            <label>用户名</label>
            <input type="text" name="username" id="" value="" class="form-control" />
        </div>
        <div id="" class="container">
            <label>邮箱</label>
            <input type="email" name="email" id="" value="" class="form-control" />
        </div>
        <div id="" class="container">
            <label>密码</label>
            <input type="password" name="password" id="" value="" class="form-control" />
        </div>
    </body>
</html>
bootstrap输入框_css