Use color palette.

imports/Spectral/Setting/Palette.qml

@@ -0,0 +1,13 @@
+pragma Singleton
+import QtQuick 2.12
+import QtQuick.Controls.Material 2.3
+
+QtObject {
+    readonly property int theme: MSettings.darkTheme ? Material.Dark : Material.Light
+
+    readonly property color primary: "#344955"
+    readonly property color accent: "#673AB7"
+    readonly property color foreground: MSettings.darkTheme ? "#FFFFFF" : "#1D333E"
+    readonly property color background: MSettings.darkTheme ? "#303030" : "#FFFFFF"
+    readonly property color lighter: MSettings.darkTheme ? "#FFFFFF" : "#5B7480"
+}

imports/Spectral/Setting/qmldir

@@ -1,3 +1,3 @@
 module Spectral.Setting
 singleton MSettings 0.1 Setting.qml
-
+singleton MPalette 0.1 Palette.qml