Fix confusing colors on filter nodes

src/components/nodes/FilterNode.vue

@@ -31,15 +31,16 @@ export default class FilterNode extends Vue {
 .filter-node {
   width: 100%;
   height: 100%;
-  background: #333;
+  background: #555;
   display: flex;
   flex-direction: column;
   position: relative;
   transition: 0.2s background;
+  border-radius: 25px;
 }
 
 .filter-node.inactive {
-  background: #555;
+  background: #888;
 }
 
 .node-name {