Make unavailable upgrades more obviously unavailable

gorge.css

@@ -354,7 +354,7 @@ button {
   width: 80px;
   height: 80px;
   display: block;
-  background-color: #444;
+  background-color: #333;
   transition: 0.2s;
   text-align: center;
   box-shadow: inset 0px 0px 0px 2px black;
@@ -370,6 +370,10 @@ button {
   transform: translate(0, 10px);
 }
 
+.upgrade-button-inactive > .upgrade-icon-holder {
+  opacity: 0.6;
+}
+
 [class^="fa-"], [class*=" fa-"] {
   display: inline-block;
   height: 100%;
@@ -388,11 +392,11 @@ button {
 }
 
 .upgrade-button.upgrade-button-inactive {
-  background-color: #222;
+  background-color: #111;
 }
 
 .upgrade-button.upgrade-button-inactive:hover {
-  background-color: #333;
+  background-color: #222;
   box-shadow: inset 0px 0px 0px 2px red;
 }