Fix external link styling in dark mode

assets/stylesheets/global/_classes.scss

@@ -152,7 +152,7 @@
     background-image: url(data:image/svg+xml;base64,PHN2ZyB2aWV3Qm94PSIwIDAgMjAgMjAiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PHBhdGggZmlsbD0iIzMzNzdjMCIgZD0iTTE1LDE1SDJWNmgyLjU5NWMwLDAsMC42ODktMC44OTYsMi4xNy0ySDFDMC40NDcsNCwwLDQuNDQ5LDAsNXYxMWMwLDAuNTUzLDAuNDQ3LDEsMSwxaDE1YzAuNTUzLDAsMS0wLjQ0NywxLTF2LTMuNzQ2IGwtMiwxLjY0NVYxNXogTTEzLjM2MSw4LjA1djMuNTUxTDIwLDYuNGwtNi42MzktNC45OTl2My4xMzFDNS4zLDQuNTMyLDUuMywxMi41LDUuMywxMi41QzcuNTgyLDguNzUyLDguOTg2LDguMDUsMTMuMzYxLDguMDV6Ii8+PC9zdmc+);
   }
 }
-html._theme-dark %external-link {
+html._theme-dark %external-link:after {
   background-image: url(data:image/svg+xml;base64,PHN2ZyB2aWV3Qm94PSIwIDAgMjAgMjAiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PHBhdGggZmlsbD0iI2NiZDBkMCIgZD0iTTE1LDE1SDJWNmgyLjU5NWMwLDAsMC42ODktMC44OTYsMi4xNy0ySDFDMC40NDcsNCwwLDQuNDQ5LDAsNXYxMWMwLDAuNTUzLDAuNDQ3LDEsMSwxaDE1YzAuNTUzLDAsMS0wLjQ0NywxLTF2LTMuNzQ2IGwtMiwxLjY0NVYxNXogTTEzLjM2MSw4LjA1djMuNTUxTDIwLDYuNGwtNi42MzktNC45OTl2My4xMzFDNS4zLDQuNTMyLDUuMywxMi41LDUuMywxMi41QzcuNTgyLDguNzUyLDguOTg2LDguMDUsMTMuMzYxLDguMDV6Ii8+PC9zdmc+);
 }