style(ui): bump seek button font-size 14px -> 19px for readability

web/static/style.css

@@ -175,7 +175,7 @@ html, body {
 .btn-seek {
   height: 52px;
   line-height: 52px;
-  font-size: 14px;
+  font-size: 19px;
   font-weight: 600;
 }