.slideout-menu {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
    z-index: 0;
    width: 256px;
    overflow-y: scroll;
    -webkit-overflow-scrolling: touch;
    display: none;
}

.slideout-panel {
    position: relative;
    z-index: 1;
    will-change: transform;
}

.slideout-open,
.slideout-open body,
.slideout-open .slideout-panel {
    overflow: hidden;
}

    .slideout-open .slideout-menu {
        display: block;
    }




.panel:before {
    content: '';
    display: block;
    background-color: rgba(0,0,0,0);
    transition: background-color 0.5s ease-in-out;
}

.panel-open:before {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 100%;
    background-color: rgba(0,0,0,.5);
    z-index: 99;
}