Add option for monochrome mode (#2464)

src/app/features/settings/general/General.tsx

@@ -305,6 +305,7 @@ function PageZoomInput() {
 
 function Appearance() {
   const [systemTheme, setSystemTheme] = useSetting(settingsAtom, 'useSystemTheme');
+  const [monochromeMode, setMonochromeMode] = useSetting(settingsAtom, 'monochromeMode');
   const [twitterEmoji, setTwitterEmoji] = useSetting(settingsAtom, 'twitterEmoji');
 
   return (
@@ -332,6 +333,13 @@ function Appearance() {
         />
       </SequenceCard>
 
+      <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
+        <SettingTile
+          title="Monochrome Mode"
+          after={<Switch variant="Primary" value={monochromeMode} onChange={setMonochromeMode} />}
+        />
+      </SequenceCard>
+
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile
           title="Twitter Emoji"