Bootstrap5 块帮助文本—

 
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap5 块帮助文本 - 迹忆客(jiyik.com)</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"></script>
</head>
<body>
<div class="m-4">
    <label class="form-label" for="inputPassword">Password</label>
    <input type="password" class="form-control" id="inputPassword">
    <div class="form-text">
        Must be 8-20 characters long, contain letters, numbers and special characters, but must not contain spaces.
    </div>
</div>
</body>
</html>