HTML <form> <div class="form-group"> <label for="name">Name:</label> <input type="text" class="form-control" id="name" required> </div> <div class="form-group"> <label for="email">Email:</label> <input type="email" class="form-control...

HTML代码 <div id="banner"> <p>This is a self-closing banner.</p> <button id="close-banner">X</button> </div> css代码 #banner { background-color: #f1f1f1; padding: 10px; position: fixed; bottom: 0; left: 0; width: 100%; text-align: c...