Implementation of task-list renaming.

src/styles.scss

@@ -1,6 +1,8 @@
 /* You can add global styles to this file, and also import other style files */
 
-html, body { height: 100%; }
+html {
+  height: 100%;
+}
 body {
   margin: 0;
   font-family: Roboto, "Helvetica Neue", sans-serif;
@@ -46,6 +48,12 @@ button {
       border-color: rgb(53, 53, 53);
   }
 
+  &:disabled {
+    background-color: #aaa;
+    color: #ccc;
+    cursor: not-allowed;
+  }
+
   &.icon {
       width: 2rem;
       height: 2rem;