(gui) Inline stage transparency (loading css can take some time)

eclair-node/src/main/resources/gui/main/notifications.fxml

@@ -5,7 +5,7 @@
 <?import javafx.scene.layout.VBox?>
 
 <Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity"
-      styleClass="notifications-box" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
+      style="-fx-background-color: transparent" styleClass="notifications-box" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
    <stylesheets>
       <URL value="@../commons/globals.css" />
       <URL value="@main.css" />

eclair-node/src/main/resources/gui/splash/splash.css

@@ -1,7 +1,3 @@
-.transparent {
-	-fx-background-color: transparent;
-}
-
 .label.splash-error-label {
     -fx-padding: .25em;
 }
@@ -9,6 +5,6 @@
 .error-box {
 	-fx-padding: 2em;
     -fx-border-width: 1px;
-    -fx-background-color: white;
+    -fx-background-color: #f6f6f6;
     -fx-border-color: rgb(80,80,80);
 }

eclair-node/src/main/resources/gui/splash/splash.fxml

@@ -10,7 +10,7 @@
 <?import java.lang.String?>
 <?import java.net.URL?>
 <Pane fx:id="splash" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity"
-      prefHeight="457.0" prefWidth="760.0" styleClass="transparent"
+      prefHeight="457.0" prefWidth="760.0" style="-fx-background-color: transparent"
       xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="fr.acinq.eclair.gui.controllers.SplashController">
     <children>
         <ImageView fx:id="imgBlurred" fitHeight="0" fitWidth="409.0" layoutX="176.0" layoutY="115.0" pickOnBounds="true" preserveRatio="true">