buttons problem

ColumnLayout {
                width: window.width
                height: window.height
                spacing: 2
                anchors.fill: parent

                Button {
                    Layout.alignment: Qt.AlignCenter
                    id: refreshButton
                    text: "Refresh"
                    Layout.preferredWidth: 140
                    Layout.minimumWidth: 10
                    height: 60
                    highlighted: true
                    Material.accent: Material.Teal
                    x: parent.width / 2 - width / 2
                    y: parent.height / 2 - height / 2

                    onClicked: {
                        console.log("Refresh")
                    }
                }

                ListView {
                    anchors.fill: parent
                    Layout.alignment: Layout.Center
                    //Layout.minimumHeight: parent.height - 110
                    anchors.topMargin: refreshButton.height + 15
                    anchors.bottomMargin: backButton.height + 15
                    height: parent.height - (refreshButton.height + backButton.height + 30)
                    width: parent.width
                    flickableDirection: Flickable.VerticalFlick
                    boundsBehavior: Flickable.StopAtBounds

                    model: 100
                    delegate: ItemDelegate {
                        text: "Item " + index
                    }
                    ScrollBar.vertical: ScrollBar {}
                }

                Button {
                    Layout.alignment: Qt.AlignCenter
                    id: backButton
                    text: "Back"
                    Layout.preferredWidth: 140
                    Layout.minimumWidth: 50
                    height: 60
                    highlighted: true
                    Material.accent: Material.Teal
                    x: parent.width / 2 - width / 2
                    y: parent.height / 2 - height / 2

                    onClicked: {
                        view.pop()
                    }
                }
            }