diff --git a/lists.Rmd b/lists.Rmd
index 525988f..cfa0efa 100644
--- a/lists.Rmd
+++ b/lists.Rmd
@@ -80,7 +80,7 @@ x3 <- list(1, list(2, list(3)))
 
 I draw them as follows:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-structure.png")
 ```
 
@@ -129,7 +129,7 @@ a <- list(a = 1:3, b = "a string", c = pi, d = list(-1, -5))
 
 Or visually:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-subsetting.png")
 ```
 
@@ -137,13 +137,13 @@ knitr::include_graphics("diagrams/lists-subsetting.png")
 
 It's easy to get confused between `[` and `[[`, but it's important to understand the difference. A few months ago I stayed at a hotel with a pretty interesting pepper shaker that I hope will help remember these differences:
 
-```{r, echo = FALSE} 
+```{r, echo = FALSE, out.width = "25%"} 
 knitr::include_graphics("images/pepper.jpg")
 ```
 
 If this pepper shaker is your list `x`, then, `x[1]` is a pepper shaker containing a single pepper packet:
 
-```{r, echo = FALSE} 
+```{r, echo = FALSE, out.width = "25%"} 
 knitr::include_graphics("images/pepper-1.jpg")
 ```
 
@@ -151,13 +151,13 @@ knitr::include_graphics("images/pepper-1.jpg")
 
 `x[[1]]` is:
 
-```{r, echo = FALSE} 
+```{r, echo = FALSE, out.width = "25%"} 
 knitr::include_graphics("images/pepper-2.jpg")
 ```
 
 If you wanted to get the content of the pepper package, you'd need `x[[1]][[1]]`:
 
-```{r, echo = FALSE} 
+```{r, echo = FALSE, out.width = "25%"} 
 knitr::include_graphics("images/pepper-3.jpg")
 ```
 
@@ -533,7 +533,7 @@ x %>% transpose() %>% str()
 
 Graphically, this looks like:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-transpose.png")
 ```
 
@@ -644,7 +644,7 @@ map2(mu, sigma, rnorm, n = 10)
 
 `map2()` generates this series of function calls:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-map2.png")
 ```
 
@@ -672,7 +672,7 @@ args1 %>% pmap(rnorm) %>% str()
 
 That looks like:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-pmap-unnamed.png")
 ```
 
@@ -685,7 +685,7 @@ args2 %>% pmap(rnorm) %>% str()
 
 That generates longer, but safer, calls:
 
-```{r, echo = FALSE}
+```{r, echo = FALSE, out.width = "75%"}
 knitr::include_graphics("diagrams/lists-pmap-named.png")
 ```