diff --git a/app/controllers.js b/app/controllers.js
index 4c1e9af..0a7a555 100644
--- a/app/controllers.js
+++ b/app/controllers.js
@@ -86,7 +86,13 @@ app.compose(function() {
         },
         update: function (cfg) {
             var emIndicator = this.viewElement.querySelector('#emphasizeBytes');
-            emIndicator.style.display = cfg.emphasizeBytes ? '' : 'none';
+            var reg = /\son/g;
+
+            if(cfg.emphasizeBytes) {
+                emIndicator.classList.add("on");
+            } else {
+                emIndicator.classList.remove("on");
+            }
         }
     });
 
diff --git a/css/styles.css b/css/styles.css
index 40d1b8b..de6ed1c 100644
--- a/css/styles.css
+++ b/css/styles.css
@@ -21,7 +21,8 @@ code { font-size: 1.2em; font-weight: bold; }
 .help { padding: 10px; background: #e0e0e0; }
 .help ul { list-style-type: none; margin: 0; padding: 0;  }
 
-.configPnl .indicator { font-size: 0.7em; background: darkblue; color: white; padding: 2px; }
+.configPnl .indicator { font-size: 0.7em; background: gray; color: white; padding: 2px; }
+.configPnl .on { background: darkblue; }
 
 .error { color: maroon; }
 
diff --git a/index.html b/index.html
index ed93dc1..a815098 100644
--- a/index.html
+++ b/index.html
@@ -46,7 +46,7 @@
     <input id="in" type="text" class="expressionInput" data-controller="expressionInputCtrl" placeholder="type expression like '1>>2' or 'help' "/>
 
     <span data-controller="configPanelCtrl" class="configPnl">
-         <span id="emphasizeBytes" class="indicator">Emphasize Bytes</span>
+         <span id="emphasizeBytes" class="indicator on"><strong>em:</strong> Emphasize Bytes</span>
     </span>
 </div>