.menu-container{
    position: absolute;
    top: 50px;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Poppins';
}
.button{
    position: relative;
    background: #1b1b1b;
    color: #fff;
    font-size: 20px;
    padding: 8px 20px;
    width: 150px;/* 100% */
    line-height: 30px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-radius: 25px;
    cursor: pointer;
    transition: width .4s;
}
.button.expand{
    width: 100%;
}
.fas{
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}
.menu-container .button span svg{
    position: absolute;
    margin-right: 15px;
    transition: 200ms;
}
.menu-container .button span svg:nth-child(1){opacity:1;}
.menu-container .button.expand span svg:nth-child(1){opacity:0;}
.menu-container .button span svg:nth-child(2){opacity:0;}
.menu-container .button.expand span svg:nth-child(2){opacity:1;}
ul{
    list-style: none;
    position: absolute;
    top: 65px;
    display: block;
    background: #1b1b1b;
    width: 100%;
    text-align: center;
    border-radius: 5px;
    display: none;
    box-shadow: 0 3px 6px rgba(0,0,0,.3);
    padding-inline-start: 0px;
}
ul:before{
    position: absolute;
    content: '';
    width: 20px;
    height: 20px;
    background: #1b1b1b;
    top: -10px;
    right: 15px;
    transform: rotate(45deg);
    z-index: -1;
}
ul li{
    line-height: 35px;
    cursor: pointer;
    border-bottom: 1px solid rgba(255,255,255,.1);
}
ul li:hover:first-child{
    border-radius: 5px 5px 0 0;
}
ul li:hover:last-child{
    border-radius: 0 0 5px 5px;
}
ul li:hover{
    box-shadow: inset 0 0 5px #33ff33,
    inset 0 0 10px #66ff66;
}
ul li:last-child{
    border-bottom: none;
}
ul li a{
    display: block;
    width: 100%;
    height: 100%;
    color: #fff;
    padding: 8px 0;
    font-size: 18px;
    text-decoration: none;
}
ul li:hover a{
    color: #44dd44;
}