feat(SVG): make icons on posts non selectable

assets/scss/style.scss

@@ -965,7 +965,8 @@ a.footnote-ref {
   animation: toxicGlow 5s ease-in-out infinite;
 }
 
-.toxicGlow img {
+.toxicGlow img,
+.hdr-social img {
   user-select: none;
   -moz-user-select: none;
   -webkit-user-drag: none;