Arrow on mega-sub-menu

Hi,
I would like an arrow on my submenu and have been trying the following.

.main-navigation .mega-sub-menu:before {
    content:"";
    position: absolute;
    right: 11px;
    top: -10px;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 0 10px 10px 10px;
    border-color: transparent transparent #fae0bb transparent;
    z-index:9999;
}

.main-navigation .mega-sub-menu:after {
    content:"";
    position: absolute;
    right: 4px;
    top: -22px;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 0 17px 17px 17px;
    border-color: transparent transparent #ffffff transparent;
    z-index:9998;
}

However, it doesn’t seems to work.

This is what I try to accomplish.

Arrow

Thank you for your time,