diff --git a/docs/config.md b/docs/config.md
index 3a09c7f2..821c4149 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -80,6 +80,9 @@ For a good example, see https://riot.im/develop/config.json.
 1. `defaultCountryCode`: The ISO 3166 alpha2 country code to use when showing
    country selectors, like the phone number input on the registration page.
    Defaults to `GB` if the given code is unknown or not provided.
+1. `settingDefaults`:  Defaults for settings that support the `config` level,
+   as an object mapping setting name to value (note that the "theme" setting
+   is special cased to the `default_theme` in the config file).
 1. `disable_custom_urls`: disallow the user to change the
    default homeserver when signing up or logging in.
 1. `permalinkPrefix`: Used to change the URL that Riot generates permalinks with.
diff --git a/webpack.config.js b/webpack.config.js
index fb16098c..5d02de3d 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -18,6 +18,8 @@ module.exports = {
         // CSS themes
         "theme-light": "./node_modules/matrix-react-sdk/res/themes/light/css/light.scss",
         "theme-dark": "./node_modules/matrix-react-sdk/res/themes/dark/css/dark.scss",
+        "theme-light-custom": "./node_modules/matrix-react-sdk/res/themes/light-custom/css/light-custom.scss",
+        "theme-dark-custom": "./node_modules/matrix-react-sdk/res/themes/dark-custom/css/dark-custom.scss",
     },
     module: {
         rules: [