* {
    margin:0;
    padding:0;
    box-sizing:border-box;
}
html, body {
    height:100%;
    background:linear-gradient(to top right, #80cbc4, #21bdd7, #80ddea, #31c4e9);
}
nav{
    width:250px;
    position: absolute;
    top:0;
    bottom:0;
    background:rgba(0, 0, 0, 0.1);
    border-radius:10px;
    box-shadow: 5px 7px 10px rgba(0, 0, 0, 0.1);
}
nav ul {
    position: relative;
    list-style-type: none;
}
nav ul li a {
    display: flex;
    align-items: center;
    font-family: arial;
    font-size: 1.2em;
    text-decoration:none;
    color: #000;
    padding: 10px 30px;
    height: 50px;
}
nav ul li a:hover {
    background: rgba(0, 0, 0, 0.7);
    color: #fff;
}
nav ul ul {
    position: absolute;
    left: 250px;
    width: 200px;
    top: 0;
    display: none;
    background:rgba( 15, 39, 176, 0.4);
    border-radius: 5px;
    box-shadow: 2px 2px, 10px rgba(0, 0, 0, 0.2);
}
nav ul li a span {
    position: absolute;
    right: 20px;
    font-size: 1.5em;
}
nav ul .dropdown {
    position: relative;
}
nav ul .dropdown:hover > ul {
    display: initial;
}
nav ul .dropdown_l2 ul {
    position: absolute;
    left: 200px;
    top: 0;
}
nav ul .dropdown_l2:hover ul {
   display: initial;
}
nav ul .sec ul {
    top: 50px;
}