Tweak avi follow button styles (#4304)

* Tighten up

* Tweak colors

* Tweak for night mode

* Add missing file

* Contrast plus

src/alf/index.tsx

@@ -1,12 +1,14 @@
 import React from 'react'
 import {Dimensions} from 'react-native'
+
 import * as themes from '#/alf/themes'
 
-export * from '#/alf/types'
-export * as tokens from '#/alf/tokens'
 export {atoms} from '#/alf/atoms'
-export * from '#/alf/util/platform'
+export * as tokens from '#/alf/tokens'
+export * from '#/alf/types'
 export * from '#/alf/util/flatten'
+export * from '#/alf/util/platform'
+export * from '#/alf/util/themeSelector'
 
 type BreakpointName = keyof typeof breakpoints