diff --git a/browser/main/modals/PreferencesModal/UiTab.js b/browser/main/modals/PreferencesModal/UiTab.js
index 29878e3e..316b7f9d 100644
--- a/browser/main/modals/PreferencesModal/UiTab.js
+++ b/browser/main/modals/PreferencesModal/UiTab.js
@@ -846,6 +846,7 @@ class UiTab extends React.Component {
                   onChange={e => this.handleUIChange(e)}
                   ref={e => (this.customCSSCM = e)}
                   value={config.preview.customCSS}
+                  defaultValue={'/* Drop Your Custom CSS Code Here */\n'}
                   options={{
                     lineNumbers: true,
                     mode: 'css',