CSS mobile menu dropdown icon color

Hello boys and girls,

please check out 247livecasino.nl on mobile. The dropdown icon is in blue and it needs to be white.

I tried this:

@media (min-width:769px) {
      .menu-item-has-children .dropdown-menu-toggle:before {
        color: #000000;}
}

No succes there... Probably because i changed the GP-icon color.. :(

Could you perhaps have a look at all these CSS adjustmets for mobile and help me make 1 code including the dropdown icon color?

@media (max-width: 720px) {
   .page-hero {
        display: none;
    }
}

@media(max-width: 720px) {
    .site-logo.mobile-header-logo img {
        height: 320px;
    }
}

@media (max-width: 720px) {
   .yoast-breadcrumbs {
        display: none;
    }
}

@media (max-width: 720px) {
.grid-container {
    padding-top: 330px;
	}}

@media (max-width: 720px) {
   .gp-icon {
        color: #111444;
    }
}

.main-navigation .main-nav li ul a {
    background-color: rgba(17, 20, 68, 0.85);
    border-radius: 10px;
    margin: 3px;
}

@media (max-width: 768px) {
    body .header-wrap .main-navigation .main-nav li a {
        color: #ffffff;
        background-color: rgba(17,20,68,0.95);
			
    }

}