Stability improvements

.gitattributes

@@ -0,0 +1 @@
+card-mod.js binary

src/main.js

@@ -2,6 +2,7 @@ import {html, css} from "/card-tools/lit-element.js";
 import {fireEvent} from "/card-tools/event.js";
 import {parseTemplate} from "/card-tools/templates.js";
 
+customElements.whenDefined('ha-card').then(() => {
   const HaCard = customElements.get('ha-card');
 
   const findConfig = function(node) {
@@ -80,3 +81,4 @@ Object.defineProperty(HaCard.prototype, 'hass', {
   });
 
   fireEvent('ll-rebuild', {});
+});