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<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.Font?>

<VBox fx:id="mainContainer" alignment="CENTER" spacing="15.0" style="-fx-background-color: #2c3e50; -fx-background-radius: 10;" xmlns="http://javafx.com/javafx/11.0.2" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.demo.HelloController">
    <padding>
        <Insets bottom="20.0" left="20.0" right="20.0" top="20.0" />
    </padding>

    <TextField fx:id="display" editable="false" alignment="CENTER_RIGHT" prefHeight="70.0" prefWidth="280.0" style="-fx-background-color: #ecf0f1; -fx-background-radius: 5; -fx-text-fill: #2c3e50; -fx-padding: 0 10 0 10;">
        <font>
            <Font name="Segoe UI Bold" size="28.0" />
        </font>
    </TextField>

    <GridPane hgap="10.0" vgap="10.0">
        <Button onAction="#onDigitClick" text="7" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="0" GridPane.rowIndex="0" />
        <Button onAction="#onDigitClick" text="8" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="1" GridPane.rowIndex="0" />
        <Button onAction="#onDigitClick" text="9" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="2" GridPane.rowIndex="0" />
        <Button onAction="#onOperatorClick" text="/" prefWidth="65" prefHeight="60" style="-fx-background-color: #f39c12; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="3" GridPane.rowIndex="0" />

        <Button onAction="#onDigitClick" text="4" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="0" GridPane.rowIndex="1" />
        <Button onAction="#onDigitClick" text="5" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="1" GridPane.rowIndex="1" />
        <Button onAction="#onDigitClick" text="6" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="2" GridPane.rowIndex="1" />
        <Button onAction="#onOperatorClick" text="*" prefWidth="65" prefHeight="60" style="-fx-background-color: #f39c12; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="3" GridPane.rowIndex="1" />

        <Button onAction="#onDigitClick" text="1" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="0" GridPane.rowIndex="2" />
        <Button onAction="#onDigitClick" text="2" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="1" GridPane.rowIndex="2" />
        <Button onAction="#onDigitClick" text="3" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="2" GridPane.rowIndex="2" />
        <Button onAction="#onOperatorClick" text="-" prefWidth="65" prefHeight="60" style="-fx-background-color: #f39c12; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="3" GridPane.rowIndex="2" />

        <Button onAction="#onDigitClick" text="0" prefWidth="65" prefHeight="60" style="-fx-background-color: #34495e; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="0" GridPane.rowIndex="3" />
        <Button onAction="#onClearClick" text="C" prefWidth="65" prefHeight="60" style="-fx-background-color: #e74c3c; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="1" GridPane.rowIndex="3" />
        <Button onAction="#onResultClick" text="=" prefWidth="65" prefHeight="60" style="-fx-background-color: #2ecc71; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="2" GridPane.rowIndex="3" />
        <Button onAction="#onOperatorClick" text="+" prefWidth="65" prefHeight="60" style="-fx-background-color: #f39c12; -fx-text-fill: white; -fx-font-weight: bold; -fx-font-size: 18;" GridPane.columnIndex="3" GridPane.rowIndex="3" />
    </GridPane>
</VBox>