Add checkerboard bg.

index.html

@@ -5,6 +5,11 @@
 html, body {
   font-family: "Calibri", "Arial", "Helvetica Neue", sans-serif;
 }
+
+.checkerboard-bg {
+  background: #eee url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="400" height="400" fill-opacity=".1" ><rect x="200" width="200" height="200" /><rect y="200" width="200" height="200" /></svg>');
+  background-size: 20px 20px;
+}
 </style>
 <noscript>
   <p>Alas, you need JavaScript to peruse this page.</p>

lib/browser-main.tsx

@@ -106,7 +106,6 @@ const App: React.FC<{}> = () => {
             display: "inline-block",
             border: "1px solid black",
             margin: "4px",
-            backgroundColor: "#f0f0f0",
           }}
         >
           <div
@@ -118,12 +117,14 @@ const App: React.FC<{}> = () => {
           >
             {symbolData.name}
           </div>
-          <SvgSymbol
-            data={symbolData}
-            scale={0.25}
-            stroke={stroke}
-            fill={fill}
-          />
+          <div className="checkerboard-bg">
+            <SvgSymbol
+              data={symbolData}
+              scale={0.25}
+              stroke={stroke}
+              fill={fill}
+            />
+          </div>
         </div>
       ))}
     </>