011 button animation

"> 버튼 "> 버튼 ">
<!DOCTYPE html>
<html lang="ko">
<head>
    <title>버튼</title>
    <style>
        .btn {
            border: 4px solid palevioletred;
            border-radius: 4px;
            padding: 30px 60px;
            background: none;
            color: palevioletred;
            font-size: 32px;
            position: relative;
            overflow: hidden;
            cursor: pointer;
            transition: all .3s;
        }

        .btn:hover {
            color: white;
            border: 4px solid firebrick;
        }

        .btn:before {
            content: "";
            position: absolute;
            bottom: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: palevioletred;
            z-index: -1;
            border-radius: 100px 100px 0px 0px;
            height: 0px;
            transition: all .3s;
        }

        .btn:hover:before {
            height: 120px;
            background: firebrick;
        }
    </style>
</head>
<body>
	<button class="btn">Click Me!!</button>
</body>
</html>