I'm using Elegant Icons and this is an example of what the content looks like for my elements (the \35 content is a down arrow icon):

<span class="submenu-icon">::after</span>

.menu-navigation-vertical ul li.menu-item-has-children .submenu-icon:after {
    font-size: 1.83333rem;
    content: '\35';
    font-family: eleganticons;
    color: #050505;
    line-height: 1;
}

The issue I'm having is that the font doesn't render correctly in older versions of OSX (specifically El Capitan and down). It shows a '3' instead of the down arrow. Is there some sort of fallback I can add to this code to show alternate content (for example, a down arrow using just html) on older versions of OSX?

@font-face {
  font-family: "ElegantIcons";
  font-style: normal;
  font-weight: normal;
  src: url("https://cdn.rawgit.com/mdentinho/elegant-icons-sass/e48e7df0/fonts/ElegantIcons.woff2") format("woff2"), url("https://cdn.rawgit.com/mdentinho/elegant-icons-sass/e48e7df0/fonts/ElegantIcons.woff") format("woff");
}