update bookdowm doc
diff --git a/docs/bookdown_example/01-cross-format.Rmd b/docs/bookdown_example/01-cross-format.Rmd
index 172b523..593d98f 100644
--- a/docs/bookdown_example/01-cross-format.Rmd
+++ b/docs/bookdown_example/01-cross-format.Rmd
@@ -27,6 +27,7 @@
 
 ```{r}
 library(kableExtra)
+options(kableExtra.html.bsTable = T)
 mtcars[1:5, 1:5] %>%
   kable(booktabs = T) %>% 
   kable_styling(