menu drop drawn (sem JS)

<!DOCTYPE html>
<html>
<head>
    <title>Menu</title>
    <meta name="viewport" content="width=device-width, user-scalable=no">
<link rel="stylesheet" type="text/css" href="estilo.css">
<style>
*{
    margin: 0;
    padding: 0;
}
.menu{
    width: 100%;
    height: 50px;
    background-color: #222;
    font-family: 'Arial';
}
.menu ul{
    list-style: none;
    position: relative;
}
.menu ul li{
    width: 150px;
    float: left;
}
.menu a{
    padding: 15px;
    display: block;
    text-decoration: none;
    text-align: center;
    background-color: #222;
    color: #fff;
}
.menu ul ul{
    position: absolute;
    visibility: hidden;
}
.menu ul li:hover ul{
    visibility: visible;
}
.menu a:hover{
    background-color: #f4f4f4;
    color: #555;
}
.menu ul ul li{
    float: none;
    border: solid 1px #ccc;
}
.menu ul ul li a{
    background-color: #069;
}
label[for="bt_menu"]{
    padding: 5px;
    background-color: #222;
    color: #fff;
    font-family: "Arial";
    text-align: center;
    font-size: 30px;
    cursor: pointer;
    width: 50px;
    height: 50px;
}
#bt_menu{
    display: none;
}
label[for="bt_menu"]{
    display: none;
}
#bt_menu:checked ~ .menu{
    margin-left: 0px;
}

@media(max-width: 800px){
    label[for="bt_menu"]{
        display: block;
    }
    .menu{
    margin-top: 5px;
    margin-left: -100%;
    transition: all .4s;
}
    .menu ul li{
        width: 100%;
        float: none;
    }
    .menu ul ul{
        position: static;
        overflow: hidden;
        max-height: 0;
        transition: all .4s;
    }
    .menu ul li:hover ul{
        height: auto;
        max-height: 100%;
    }
}

</style>
</head>
<body>
    <input type="checkbox" id="bt_menu">
    <label for="bt_menu">&#9776;</label>
    <nav class="menu">
        <ul>
            <li><a href="#">Home</a></li>
            <li><a href="#">Serviços</a>
                <ul>
                    <li><a href="#">Ciaçao de Sites</a></li>
                    <li><a href="#">Artes Visuais</a></li>
                </ul>
            </li>
            <li><a href="#">Cursos</a>
                <ul>
                    <li><a href="#">Java</a></li>
                    <li><a href="#">PHP</a></li>
                    <li><a href="#">HTML/CSS</a></li>
                </ul>
            </li>
            <li><a href="#">Contato</a></li>
        </ul>
    </nav>
</body>
</html>