static: add playback arrow image + red highlight background color

static/flexbox/sanic.css

@@ -32,7 +32,7 @@ td {
 }
 
 #queue-table tr td:first-of-type {
-  padding-left: 20px;
+  padding-left: 16px;
 }
 
 /* This is probably a better way to generate alternate coloring on tables. However,
@@ -56,6 +56,16 @@ table tr.even {
   background-color: #171812;
 }
 
+#queue-table tr.playing {
+  background-color: #490b00;
+}
+
+td.playing {
+  background-image: url(../img/playback.png);
+  background-repeat: no-repeat;
+  background-position: left center;
+}
+
 #flexbox-container {
   display: flex;
   flex-direction: column;