Features
- Automatically resize wysiwyg and textarea fields in ACF groups
- Add data-wysiwyg-slug='my-wysiwyg-field'to the body in tinymce iframes, so you can style those iframe's contents using editor-styles.
Usage
- Install and activate like any other wordpress plugin
- [data-wysiwyg-slug]is added to every wysiwyg field!
- The plugin is enabled by default on all textareas and wysiwyg fields. You can disable it by adding the class no-autosizeto a field.
- You can set the the default behaviour to false via the acf-autosize/enabledByDefault-filter. After that you can reenable single fields by adding the classautosize.
- Set min-heightof WYSIWYG-fields viaacf-autosize/wysiwyg/min-height-filter.
mu-plugin
acf-autosize-mu.php is a single-file drop-in version of acf-autosize for usage in your theme or mu-plugins. It contains the javascript and is autogenerated!
Development
Check out the source code 
on Github!