diff --git a/mkdocs.yml b/mkdocs.yml
index 83f0517..1eee11f 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -62,10 +62,10 @@ nav:
   - Home: index.md
   - Books:
     - Designing Data-Intensive Applications:
-        - Preface: books/designing_data_intensive_applications/preface/index.md
-        - Part 1. Foundations of Data Systems:
-          - Chapter 1. Reliable, Scalable and Maintainable Applications: books/designing_data_intensive_applications/part1/chapter1.md
-          - Chapter 2. Data Models and Query Languages: books/designing_data_intensive_applications/part1/chapter2.md
+      - Preface: books/designing_data_intensive_applications/preface/index.md
+      - Part 1. Foundations of Data Systems:
+        - Chapter 1. Reliable, Scalable and Maintainable Applications: books/designing_data_intensive_applications/part1/chapter1.md
+        - Chapter 2. Data Models and Query Languages: books/designing_data_intensive_applications/part1/chapter2.md
     - API Design Patterns:
       - Part 1. Introduction:
         - Chapter 1. Introduction to APIs: books/api_design_patterns/part1/chapter1.md