Remove unused CSS

static/css/app.css

@@ -40,18 +40,6 @@ body {
     padding: 0px 5px;
 }
 
-.mgn-btm-10px {
-    margin-bottom: 10px;
-}
-
-.mgn-top-8px {
-    margin-top: 8px;
-}
-
-.black-text {
-    color: black;
-}
-
 .footer {
     margin-top: 10em;
     text-align: center;