Live Demo: Bootstrap Clean Modal Login Modal Form

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>Bootstrap Clean Modal Login Modal Form</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto|Varela+Round">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
<style>
body {
	font-family: 'Varela Round', sans-serif;
}
.modal-login {
	width: 350px;
}
.modal-login .modal-content {
	padding: 20px;
	border-radius: 1px;
	border: none;
}
.modal-login .modal-header {
	border-bottom: none;
	position: relative;
	justify-content: center;
}
.modal-login h4 {
	text-align: center;
	font-size: 26px;
}
.modal-login .form-group {
	margin-bottom: 20px;
}
.modal-login .form-control, .modal-login .btn {
	min-height: 40px;
	border-radius: 30px; 
	font-size: 15px;
	transition: all 0.5s;
}
.modal-login .form-control {
	font-size: 13px;
}
.modal-login .form-control:focus {
	border-color: #a177ff;
}
.modal-login .hint-text {
	text-align: center;
	padding-top: 10px;
}
.modal-login .close {
	position: absolute;
	top: -5px;
	right: -5px;
}
.modal-login .btn, .modal-login .btn:active {
	border: none;
	background: #a177ff !important;
	line-height: normal;
}
.modal-login .btn:hover, .modal-login .btn:focus {
	background: #8753ff !important;
}
.modal-login .hint-text a {
	color: #999;
}
.trigger-btn {
	display: inline-block;
	margin: 100px auto;
}
</style>
</head>
<body>
<div class="text-center">
	
	<a href="#myModal" class="trigger-btn" data-toggle="modal">Click to Open Login Modal</a>
</div>

<div id="myModal" class="modal fade">
	<div class="modal-dialog modal-login">
		<div class="modal-content">
			<div class="modal-header">				
				<h4 class="modal-title">Sign in</h4>
				<button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
			</div>
			<div class="modal-body">
				<form action="/examples/actions/confirmation.php" method="post">
					<div class="form-group">
						<input type="text" class="form-control" placeholder="Username" required="required">
					</div>
					<div class="form-group">
						<input type="password" class="form-control" placeholder="Password" required="required">
					</div>
					<div class="form-group">
						<input type="submit" class="btn btn-primary btn-block btn-lg" value="Sign in">
					</div>
				</form>				
				<p class="hint-text small"><a href="#">Forgot Your Password?</a></p>
			</div>
		</div>
	</div>
</div>     
</body>
</html>