Reduce font-size of bigMarkAsRead

See https://github.com/marienfressinaud/FreshRSS/issues/480

p/themes/Origine/origine.css

@@ -809,7 +809,6 @@ a.btn {
 }
 #bigMarkAsRead:hover {
 	color: #27ae60;
-	text-shadow: 0 0 2px #27ae60;
 	background: #fff;
 }
 #bigMarkAsRead:hover .bigTick {

p/themes/base-theme/template.css

@@ -519,7 +519,7 @@ a.btn {
 	width: 100%;
 	padding: 1em 0;
 	text-align: center;
-	font-size: 1.8em;
+	font-size: 1.4em;
 }
 .bigTick {
 	font-size: 4em;