Feat/loading animation

Loading animation for upload,signin and login scenes #35 (closed)

src/main/App/Css/Css.java

 package Css;
 
 import javafx.geometry.Pos;
-import javafx.scene.control.Button;
-import javafx.scene.control.Label;
-import javafx.scene.control.ScrollPane;
-import javafx.scene.control.TextField;
+import javafx.scene.control.*;
 import javafx.scene.layout.HBox;
 import javafx.scene.layout.Pane;
 import javafx.scene.text.Font;
@@ -273,6 +270,14 @@ public class Css {
         }
     }
 
+    public static void setLoadingAnimation(ProgressIndicator... args){
+        for(ProgressIndicator progressIndicator : args){
+            progressIndicator.setStyle("-fx-progress-color: dimgrey; -fx-cursor: wait");
+            progressIndicator.setMaxSize(30,30);
+            progressIndicator.setVisible(false);
+        }
+    }
+
     public static void setHomeButton(Button button) {
         button.setStyle("-fx-background-color: none;");
         button.setOnMouseEntered((e) -> {