styles.css

* {
    margin: 0;
    padding: 0;
    list-style: none;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background-color: #232323;
    color: #CDCDCD;
}

main {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.menu .menu-faketrigger {
    position: absolute;
    z-index: 1000;
    width: 35px;
    height: 35px;
    opacity: 0;
    cursor: pointer;
}

.menu .menu-lines{
    position: absolute;
    z-index: 999;
    width: 35px;
    height: 35px;
}

.menu .menu-lines span {
    display: block;
    width: 35px;
    height: 5px;
    margin-bottom: 10px;
    background-color: #cdcdcd;
    border-radius: 3px;
    transition: all ease .2s;
}

.menu .menu-faketrigger:checked ~ .menu-lines span {
    /* background-color: #232323; */
}

.menu .menu-faketrigger:checked ~ .menu-lines span:nth-child(1) {
    transform-origin: 0% 0%;
    transform: rotate(45deg) scaleX(1.25);
}

.menu .menu-faketrigger:checked ~ .menu-lines span:nth-child(2) {
    opacity: 0;
}

.menu .menu-faketrigger:checked ~ .menu-lines span:nth-child(3) {
    transform-origin: 0% 100%;
    transform: rotate(-45deg) scaleX(1.25); 
}

.menu ul {
    position: absolute;
    z-index: 998;
    left: 0;
    top: 0;
    width: 300px;
    background-color: #ededed;
    height: calc(100vh - 100px);
    padding-top: 100px;
    margin-left: -300px;
    transition: all ease .2s;
}

.menu {
    margin-left: 30px;
    margin-top: 30px;
}

.menu .menu-faketrigger:checked ~ ul {
    margin-left: 0;
}

.menu ul li {
    padding: 10px 30px;
}

.menu ul li a {
    text-decoration: none;
    color: #000;
    font-size: 22px;
    transition: all ease .5s;
}

.menu ul li a:hover {
    color: #999;
}