.middle {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%)
}

.menu {
    width: auto;
    border-radius: 8px;
    overflow: hidden;
}

.item {
    /*border-top: 1px solid #18dcff;*/
    border-top: 1px solid #767676;
    overflow: hidden;
}

.btn_acc {
    display: block;
    padding: 16px 20px;
    background: #767676;
    color: white;
    position: relative;
}

.btn_acc::before {
    content: "";
    position: absolute;
    width: 14px;
    height: 14px;
    background: #767676;
    left: 20px;
    bottom: -7px;
    transform: rotate(45deg);
}

.btn_acc i {
    margin-right: 10px;
}

.smenu {
    background: #e3e3e3;
    overflow: hidden;
    transition: max-height 0.3s;
    max-height: 0;
}

.smenu a {
    display: block;
    padding: 16px 26px;
    color: white;
    margin: 4px 0;
    position: relative;
}

.smenu a::before {
    content: "";
    position: absolute;
    width: 6px;
    height: 100%;
    background: #e8e8e8;
    left: 0;
    top: 0;
    transition: .3s;
    opacity: 0;
}

.smenu a:hover::before {
    opacity: 1;
}

.item:target .smenu {
    max-height: 10em;
}