Remove focus outlines in Firefox.

app/assets/main.css

@@ -25,6 +25,10 @@ main {
 	margin: 20px;
 }
 
+::-moz-focus-inner {
+	border: none;
+}
+
 button#playpause {
 	border: none;
 	background: none;
@@ -65,6 +69,7 @@ input#volume::-moz-range-thumb {
 	width: 20px;
 	background-color: #999;
 	border-radius: 3px;
+	border: none;
 }
 
 input#volume::-webkit-slider-thumb {