Adds a zero pill for sidebar items (#1350)

* testing class name

* updates hex color

Author: ZPain8464

src/css/custom.css

@@ -216,6 +216,20 @@ select:focus {
   color: #ffffff;
 }
 
+.zero a:before {
+  font-size: 11px;
+  background: #49AAA1;
+  margin-right: 5px;
+  padding: 2px;
+  content: 'ZERO';
+  color: #000000;
+  font-weight: bold;
+}
+
+[data-theme='dark'] .zero a:before {
+  color: #ffffff;
+}
+
 td > .theme-code-block:last-child {
   margin-bottom: 0;
 }