Fix ModalOverlay readability by removing background transparency

src/qt/forms/modaloverlay.ui

@@ -32,7 +32,7 @@
    <item>
     <widget class="QWidget" name="bgWidget" native="true">
      <property name="styleSheet">
-      <string notr="true">#bgWidget { background: rgba(0,0,0,220); }</string>
+      <string notr="true"></string>
      </property>
      <layout class="QVBoxLayout" name="verticalLayoutMain" stretch="1">
       <property name="leftMargin">

src/qt/modaloverlay.cpp

@@ -27,6 +27,12 @@ userClosed(false)
         raise();
     }
 
+    // Set opaque background using palette
+    QPalette pal = ui->bgWidget->palette();
+    pal.setColor(QPalette::Window, pal.color(QPalette::Window));
+    ui->bgWidget->setAutoFillBackground(true);
+    ui->bgWidget->setPalette(pal);
+
     blockProcessTime.clear();
     setVisible(false);
     if (!enable_wallet) {