diff --git a/book/features/HTML_javascript.md b/book/features/HTML_javascript.md
index 5962e3a..dc1abdc 100644
--- a/book/features/HTML_javascript.md
+++ b/book/features/HTML_javascript.md
@@ -12,18 +12,18 @@ In this section, we will discuss how to [create](creating_basic_HTML_elements.md
 This could be for example interactive 3d figures:
 
 ```{iframe} ../_static/element_render_box.html
-:width: 600
-:height: 400
+:width: 600px
+:height: 400px
 ```
 
 Or other interactive graphs:
 
 ```{iframe} ../_static/element_pdf_and_cdf.html
-:width: 600
-:height: 300
+:width: 600px
+:height: 300px
 ```
 
 ```{iframe} https://openla.ewi.tudelft.nl/applet/lines_and_planes/normal_equation_plane_origin?iframe=true
-:width: 600
-:height: 500
+:width: 600px
+:height: 500px
 ```
\ No newline at end of file
diff --git a/book/features/adding_HTML_elements.md b/book/features/adding_HTML_elements.md
index 3866614..3e46b49 100644
--- a/book/features/adding_HTML_elements.md
+++ b/book/features/adding_HTML_elements.md
@@ -5,8 +5,8 @@
 In this section, we will discuss how to embed interactive elements created in HTML/JavaScript in a TeachBook. If you are interested in learning how to create these elements yourself, we will discuss an example in the [next article](creating_basic_HTML_elements.md). As an example, let us discuss how to embed an interactive 3D model of a subsurface environment I created:
 
 ```{iframe} ../_static/element_render_box.html
-:width: 600
-:height: 400
+:width: 600px
+:height: 400px
 ```
 
 ## Storing the HTML file
@@ -17,8 +17,8 @@ If we want to embed our HTML/JS element in a Markdown page, we must use an inlin
 
 ````
 ```{iframe} ../_static/element_render_box.html
-:width: 600
-:height: 300
+:width: 600px
+:height: 300px
 ```
 ````
 
diff --git a/book/features/creating_basic_HTML_elements.md b/book/features/creating_basic_HTML_elements.md
index 0ee8f54..5bedc30 100644
--- a/book/features/creating_basic_HTML_elements.md
+++ b/book/features/creating_basic_HTML_elements.md
@@ -1,8 +1,8 @@
 # Creating basic interactive HTML/JavaScript elements
 
 ```{iframe} ../_static/element_pdf_and_cdf.html
-:width: 600
-:height: 300
+:width: 600px
+:height: 300px
 ```
 
 At the bottom of this page, I will provide the full code for the interactive element above. In this section, let us go through the code one piece at a time. Let us begin from the top.