diff --git a/_config.yml b/_config.yml
index f6b2215caeb2813b441e1d4730a305b0193fd1bd..e1130a776a33abda50aade4949727adf9d381e02 100644
--- a/_config.yml
+++ b/_config.yml
@@ -36,6 +36,7 @@ bibtex_bibfiles:
 sphinx:
   config:
     # html_js_files necessary for interactive plot (plotly) in ch. 2, but breaks applet in ch. 3. cf. https://jupyterbook.org/en/stable/interactive/interactive.html?highlight=html_js_files#plotly
+    language: en
     html_js_files:
     - https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.6/require.min.js
     mathjax3_config:
diff --git a/content/credits.md b/content/credits.md
index f8ded35139191da06bf387ed93e58f27ce109a75..6635f6b5992faa9366cbf8b53ec036fe1d7b80b4 100644
--- a/content/credits.md
+++ b/content/credits.md
@@ -5,20 +5,19 @@
 ---
 width: 200
 align: right
+alt: Dr. Timon Idema
 ---
 Dr. Timon Idema
 ```
-Dr. Timon Idema. Dr. Idema is an associate professor at the [Department of Bionanoscience](https://www.tudelft.nl/en/faculty-of-applied-sciences/about-faculty/departments/bionanoscience/) at [Delft University of Technology](http://www.tudelft.nl/) (TU Delft) in The Netherlands. Before starting his research group in Delft in 2012, Idema obtained his PhD in theoretical biophysics at the [Instituut Lorentz](http://www.lorentz.leidenuniv.nl/) of [Leiden University](https://www.leidenuniv.nl) (The Netherlands) and worked at the [Institut Curie](https://institut-curie.org/) (Paris, France) and the [University of Pennsylvania](https://www.upenn.edu/) (Philadelphia, USA).
+Dr. **Timon Idema** is an associate professor at the [Department of Bionanoscience](https://www.tudelft.nl/en/faculty-of-applied-sciences/about-faculty/departments/bionanoscience/) at [Delft University of Technology](http://www.tudelft.nl/) (TU Delft) in The Netherlands. Before starting his research group in Delft in 2012, Idema obtained his PhD in theoretical biophysics at the [Instituut Lorentz](http://www.lorentz.leidenuniv.nl/) of [Leiden University](https://www.leidenuniv.nl) (The Netherlands) and worked at the [Institut Curie](https://institut-curie.org/) (Paris, France) and the [University of Pennsylvania](https://www.upenn.edu/) (Philadelphia, USA).
 
 Idema's group studies collective dynamics in biologically motivated systems, ranging from proteins at the nano scale to tissues and even populations at the micro- and macro scale. A theorist himself, Idema frequently collaborates and co-publishes with experimental groups. He also teaches a number of courses at TU Delft, ranging from introductory physics to courses on soft matter and geometry that take students to the cutting edge of current research. Since the fall of 2020, Idema leads the joint-degree [MSc Nanobiology programme](https://www.tudelft.nl/onderwijs/opleidingen/masters/nanobiology/msc-nanobiology) of TU Delft and the Erasmus MC Rotterdam. For his educational work, Idema received various prizes, including the faculty of applied sciences Teacher of the Year in 2019, the J.B. Westerdijkprize in 2020, a TU Delft education fellowship (2020-2022) and an open education ambassador award (2023).
 
-
 For more details on his group's research and teaching activities, visit their website at [idemalab.tudelft.nl](https://idemalab.tudelft.nl).
 
-
-
-
 ## Software and license
 This website is a [Jupyter Book](https://jupyterbook.org/intro.html). Markdown source files are available for download using the button on the top right.
 
-This book is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.
+The cover image of the [Golden Gate bridge](https://en.wikipedia.org/wiki/Golden_Gate_Bridge) showing the Pacific Ocean and the moon in the sky is by [Varun Yadav](https://unsplash.com/@vay2250), from [Unsplash](https://unsplash.com/photos/QhYTCG3CTeI), public domain.
+
+This book is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.
diff --git a/content/images/bookcover.png b/content/images/bookcover.png
new file mode 100644
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diff --git a/index.md b/index.md
index d4cb9e2c5c9114afc38f47d429a01d96986fa834..c1b33a8d0625628f7aa4c0ece271241985a7ab9b 100644
--- a/index.md
+++ b/index.md
@@ -1,6 +1,13 @@
 Introduction to particle and continuum mechanics
 ================================================
 
+```{figure} content/images/bookcover.png
+---
+width: 200
+align: right
+alt: Introduction to particle and continuum mechanics
+---
+```
 In this book, you'll find an introduction into the physics of mechanical systems. The material in the book has evolved from lecture notes on courses in introductory physics I have taught at TU Delft since 2012. In most cases, not all of the material covered in the book were discussed in the lectures. In particular sections indicated with a star are extra material, for those interested in learning more. The chapters also do not necessarily be taught or read in the order I have presented them. For example, many of the concepts of {numref}`ch:oscillations` can be understood based on the material covered in {numref}`ch:mechanicsintroduction`-{numref}`ch:energy`. There are thus multiple paths you can take, and I encourage you to look ahead sometimes to see how what is yet to come ties in with what is discussed at a given point in the book. If you need refresher on some of the mathematical techniques, {numref}`app:math` contains some useful background maths. Throughout, I've tried to alternate theory with worked examples, to give you an idea about what you can actually do with the theory just developed.
 
 Roughly the first part of this book ({numref}`ch:mechanicsintroduction`-{numref}`ch:oscillations` and {numref}`ch:waves`) also appear in *[Mechanics and Relativity](https://textbooks.open.tudelft.nl/textbooks/catalog/book/14)* (TU Delft Open, 2018). Where applicable, I've made corrections and occasional small extensions, which will also appear in an updated version of *Mechanics and Relativity*, together with the extra {numref}`ch:Lagrangianmechanics` on Lagrangian mechanics. In turn, the new chapters on continuum materials connect to the MSc-level book I'm currently writing on soft matter physics.
@@ -36,7 +43,7 @@ In doing research or applications today, we are, in Newton's words, standing on
 
 ---
 
-This book is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.
+This book is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.
 
 This website is a [Jupyter Book](https://jupyterbook.org/intro.html). MarkDown source files are available for download using the button on the top right.