Add this to your override.css. You dont have to copy header & rest of page. Just labelled so you know what arrows you are changing. Border-color will change the outer color or the circle and color will change the inner arrow.
/* HEADER */
#gkHeaderMod .gkSectionNav:before, #gkBottom3 .gkSectionNav:before {
border-color: #fff;
color: #fff;
}
#gkHeaderMod .gkSectionNav:hover:before, #gkBottom3 .gkSectionNav:hover:before {
border-color: #e74c3c;
color: #e74c3c;
}
/* REST OF PAGE */
.gkSectionNav:before {
border: 2px solid #e74c3c;
color: #e74c3c;
}
.gkSectionNav:hover:before {
border-color: #c6c6c6;
color: #c6c6c6;
}