div.middle {
    z-index: 3;
    width: calc((100vw/3) + 100px);
    background: url(./backgrounds/blue.png);
    position: relative;
}

div.midDivider1, div.midDivider2 {
    height: 100%;
    width: 20px;
    position: absolute;
    background: url(./img/panelVertical.png);
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}

div.midDivider1 {
    left: 0;
}

div.midDivider2 {
    right: 0;
}