Style navigation links – Marquee template

Site URL: http://www.yimthai.com.au/

I am using the Marquee template, and I have two "links" in my site navigation, which link to an external website in a new tab.

It seems that my template automatically styles these links similar to a button, with a background colour behind them, and a smaller font.

However, I can't find how I can change the styling of these links. I have searched the Design > Site Styles, and in the navigation there are only options to style the "page" navigation items, not the "links".

Any help would be much appreciated – surely this can be done through the Squarespace interface.

Thank you in advance

I think the external-link style is created in the template stylesheet, you can change by adding this to custom css

.nav-wrapper li.external-link a span {
    color: #fff !important;
    font-size: inherit !important;
}
.nav-wrapper li.external-link a:hover {
  opacity: 0.8;
}
.nav-wrapper li.external-link a {
    border: none;
    padding: 10px;
    background: transparent;
    font-size: inherit !important;
}
@media only screen and (min-width: 1200px) {
      .main-nav ul {
        width: 1024px;
      }
}