fix reader features not working on insert-at-bottom

reader.html

@@ -49,6 +49,7 @@ button
     opacity: 0.35;
     position: fixed;
     right: 5px;
+    height: 2em;
     bottom: calc( 10px + 2em );
 }
 #button_delete
@@ -56,6 +57,7 @@ button
     opacity: 0.35;
     position: fixed;
     right: 5px;
+    height: 2em;
     bottom: 5px;
 }
 </style>