Tiny change to the expandable-chapters plugin from https://github.com/DomainDrivenArchitecture/ to use smaller arrows.
Add it to your book.json configuration:
{
plugins: ["expandable-chapters"]
}
Install your plugins using:
$ gitbook install
There is no configuration needed at the moment, can be left empty.
{
"pluginsConfig": {
"expandable-chapters":{}
}
}
Maybe you will find https://github.com/poojan/gitbook-plugin-toggle-chapters also useful?