added dark mode and margin changes

outputframe-app/elements/render-canvas/render-canvas.less

@@ -17,4 +17,12 @@ render-canvas canvas {
     transform: translate(-50%, -50%);
     border: 1px solid #c2c2c2;
     background-color: white;
+}
+
+
+@media (prefers-color-scheme: dark) {
+    render-canvas canvas {
+        background-color: #2c2c2c;
+        border-color: #3a3a3a;
+    }
 }