only child interfered with other uses. Instead pass class strings to the lineClass prop and it will be injected into the placeholder element

src/scss/loading-placeholder.scss

@@ -42,10 +42,13 @@
     margin: 10px;
     animation: pulse 1s infinite ease-in-out;
 
-    &:only-child {
-      margin: 0;
+    &.short {
       width: 60px !important;
     }
+
+    &.nomargin {
+      margin: 0;
+    }
   }
 
   div {