fix: sharpens radio input edges by replacing box-shadow trick with border property (#768)

Author: JarrodMFlesch

src/admin/components/forms/field-types/RadioGroup/RadioInput/index.scss

@@ -20,13 +20,13 @@
     border-radius: 50%;
 
     &:before {
-      content: ' ';
+      content: " ";
       display: block;
       border-radius: 100%;
       background-color: var(--theme-elevation-800);
-      width: 100%;
-      height: 100%;
-      box-shadow: inset 0 0 0 base(.1875) var(--theme-elevation-0);
+      width: calc(100% - 10px);
+      height: calc(100% - 10px);
+      border: 5px solid var(--theme-elevation-0);
       opacity: 0;
     }
   }