diff --git a/book-example/book.toml b/book-example/book.toml
index 4dbc659c..4679a3a2 100644
--- a/book-example/book.toml
+++ b/book-example/book.toml
@@ -3,4 +3,5 @@ description = "Create book from markdown files. Like Gitbook but implemented in
 author = "Mathieu David"
 
 [output.html]
-mathjax-support = true
\ No newline at end of file
+additional-css = ["my_custom.css"]
+mathjax-support = true
diff --git a/book-example/src/format/config.md b/book-example/src/format/config.md
index 463c430d..aa8a107e 100644
--- a/book-example/src/format/config.md
+++ b/book-example/src/format/config.md
@@ -16,9 +16,11 @@ description = "The example book covers examples."
 
 [output.html]
 destination = "my-example-book"
-additional-css = ["custom.css"]
+additional-css = ["my_custom.css"]
 ```
 
+<div class="custom_border">Formatting elements with custom css.</div>
+
 ## Supported configuration options
 
 It is important to note that **any** relative path specified in the in the configuration will
diff --git a/book-example/src/misc/contributors.md b/book-example/src/misc/contributors.md
index 36b50fad..54803917 100644
--- a/book-example/src/misc/contributors.md
+++ b/book-example/src/misc/contributors.md
@@ -11,3 +11,4 @@ If you have contributed to mdBook and I forgot to add you, don't hesitate to add
 - Wayne Nilsen ([waynenilsen](https://github.com/waynenilsen))
 - [funnkill](https://github.com/funkill)
 - Fu Gangqiang ([FuGangqiang](https://github.com/FuGangqiang))
+- Stefan Schindler ([dns2utf8](https://github.com/dns2utf8))