diff --git a/docs/awesome_table_in_pdf.Rmd b/docs/awesome_table_in_pdf.Rmd
index acd8a75..fe9e7f6 100644
--- a/docs/awesome_table_in_pdf.Rmd
+++ b/docs/awesome_table_in_pdf.Rmd
@@ -327,7 +327,9 @@
 ```
 
 ## Group rows via multi-row cell
-Function `group_rows` is great for showing simple structural information on rows but sometimes people may need to show structural information with multiple layers. When it happens, you may consider to use `collapse_rows` instead, which will put repeating cells in columns into multi-row cells. If you even need to specify column/row format, use `column_spec` & `row_spec` before you pipe it into `collapse_rows`.
+Function `group_rows` is great for showing simple structural information on rows but sometimes people may need to show structural information with multiple layers. When it happens, you may consider to use `collapse_rows` instead, which will put repeating cells in columns into multi-row cells. 
+
+In LaTeX, `collapse_rows` adds some extra hlines to help differentiate groups. You can customize this behavior using the `latex_hline` argument. You can choose from `full` (default), `major` and `none`.
 
 ```{r}
 collapse_rows_dt <- data.frame(C1 = c(rep("a", 10), rep("b", 5)),
@@ -336,7 +338,7 @@
                  C4 = sample(c(0,1), 15, replace = TRUE))
 kable(collapse_rows_dt, format = "latex", booktabs = T, align = "c") %>%
   column_spec(1, bold=T) %>%
-  collapse_rows(columns = 1:2)
+  collapse_rows(columns = 1:2, latex_hline = "major")
 ```
 
 ```{r}
diff --git a/docs/awesome_table_in_pdf.pdf b/docs/awesome_table_in_pdf.pdf
index 832e929..c9c5f0f 100644
--- a/docs/awesome_table_in_pdf.pdf
+++ b/docs/awesome_table_in_pdf.pdf
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