Improved readability of translucent tooltips

Author: lorenzos

client/components/Tooltip.css

@@ -5,7 +5,7 @@
   border-radius: 4px;
   background: #fff;
   border: 1px solid #aaa;
-  opacity: 0.7;
+  opacity: 0.9;
   white-space: nowrap;
   visibility: visible;
   transition: opacity .2s ease, visibility .2s ease;