Tweak button rendering to work for HA 2021.11.

src/scss/button.scss

@@ -7,6 +7,7 @@ ha-icon-button.button {
   padding: 0px;
   margin: 3px;
   --mdc-icon-button-size: 40px;
+  --ha-icon-display: block;
   /* Buttons can always be clicked */
   pointer-events: auto;
 }