diff --git a/vignettes/awesome_table_in_html.Rmd b/vignettes/awesome_table_in_html.Rmd
index e042f65..705b370 100644
--- a/vignettes/awesome_table_in_html.Rmd
+++ b/vignettes/awesome_table_in_html.Rmd
@@ -143,6 +143,135 @@
   row_spec(3:5, bold = T, color = "white", background = "#D7261E")
 ```
 
+
+
+## Header Rows
+One special case of `row_spec` is that you can specify the format of the header row via `row_spec(row = 0, ...)`. 
+```{r}
+kable(dt, format = "html") %>%
+  kable_styling("striped", full_width = F) %>%
+  row_spec(0, angle = -45)
+```
+
+# Cell/Text Specification
+Function `cell_spec` is introduced in version 0.6.0 of `kableExtra`. Unlike `column_spec` and `row_spec`, **this function is designed to be used before the data.frame gets into the `kable` function**. Comparing with figuring out a list of 2 dimentional index for targeted cells, this design is way easier to learn and use and it fits perfectly well with `dplyr`'s `mutate` and `summarize` functions. With this design, there are two things to be noted:
+* Since `cell_spec` generates raw `HTML` or `LaTeX` code, make sure you remember to put `escape = FALSE` in `kable`. At the same time, you have to escape special symbols including `%` manually by yourself
+* `cell_spec` needs a way to know whether you want `html` or `latex`. You can specify it locally in function or globally via the `options(knitr.table.format = "latex")` method as suggested at the beginning. If you don't provide anything, this function will output as HTML by default. 
+
+Currently, `cell_spec` supports features including bold, italic, monospace, text color, background color, align, font size & rotation angle. More features may be added in the future. Please see function documentations as reference. 
+
+## Conditional logic
+It is very easy to use `cell_spec` with conditional logic. Here is an example.
+```{r, message=FALSE, warning=FALSE}
+library(dplyr)
+mtcars[1:10, 1:2] %>%
+  mutate(
+    car = row.names(.),
+    # You don't need format = "html" if you have ever defined options(knitr.table.format)
+    mpg = cell_spec(mpg, "html", color = ifelse(mpg > 20, "red", "blue")),
+    cyl = cell_spec(cyl, "html", color = "white", align = "c", angle = 45, 
+                    background = factor(cyl, c(4, 6, 8), 
+                                        c("#666666", "#999999", "#BBBBBB")))
+  ) %>%
+  select(car, mpg, cyl) %>%
+  kable("html", escape = F) %>%
+  kable_styling("striped", full_width = F)
+```
+
+## Visualize data with Viridis Color
+This package also comes with a few helper functions, including `spec_color`, `spec_font_size` & `spec_angle`. These functions can rescale continuous variables to certain scales. For example, function `spec_color` would map a continuous variable to any [viridis color palettes](https://cran.r-project.org/web/packages/viridis/vignettes/intro-to-viridis.html). It offers a very visually impactful representation in a tabular format. 
+
+```{r}
+iris[1:10, ] %>%
+  mutate_if(is.numeric, function(x) {
+    cell_spec(x, "html", bold = T, color = spec_color(x, end = 0.9),
+              font_size = spec_font_size(x))
+  }) %>%
+  mutate(Species = cell_spec(
+    Species, "html", color = "white", bold = T,
+    background = spec_color(1:10, end = 0.9, option = "A", direction = -1)
+  )) %>%
+  kable("html", escape = F, align = "c") %>%
+  kable_styling("striped", full_width = F)
+```
+
+In the example above, I'm using the `mutate` functions from `dplyr`. You don't have to use it. Base R solutions like `iris$Species <- cell_spec(iris$Species, color = "red")` also works. 
+
+## Text Specification
+If you check the results of `cell_spec`, you will find that this function does nothing more than wrapping the text with appropriate HTML/LaTeX formatting syntax. The result of this function is just a vector of character strings. As a result, when you are writing a `rmarkdown` document or write some text in shiny apps, if you need extra markups other than **bold** or *italic*, you may use this function to `r text_spec("color", color = "red")`, `r text_spec("change font size ", font_size = 16)` or `r text_spec("rotate", angle = 30)` your text. 
+
+An aliased function `text_spec` is also provided for a more literal writing experience. In HTML, there is no difference between these two functions. 
+
+```{r}
+sometext <- strsplit(paste0(
+  "You can even try to make some crazy things like this paragraph. ", 
+  "It seems to be a useless feature at this moment but who cares. ", 
+  "It is so fun to play with color that I can't stop. ;D"
+), " ")[[1]]
+text_formatted <- paste(
+  text_spec(sometext, "html", color = spec_color(1:length(sometext), end = 0.9),
+            font_size = spec_font_size(1:length(sometext), begin = 5, end = 20)),
+  collapse = " ")
+
+# To display the text, type `r text_formatted` outside of the chunk
+```
+`r text_formatted`
+
+## Tooltip
+It's very easy to add a tooltip to text via `cell_spec`. For example, `text_spec("tooltip", color = "red", tooltip = "Hello World")` will give you something like `r text_spec("Hover over me", color = "red", tooltip = "Hello World")` (you need to wait for a few seconds before your browser renders it). 
+
+Note that the original browser-based tooltip is slow. If you want to have a faster response, you may want to initialize bootstrap's tooltip by putting the following HTML code on the page. 
+```
+<script>
+$(document).ready(function(){
+    $('[data-toggle="tooltip"]').tooltip(); 
+});
+</script>
+```
+
+In a rmarkdown document, you can just drop it outside of any R chunks. Unfortunately however, for rmarkdown pages with a **floating TOC** (like this page), you can't use bootstrap tooltips because there is a conflict in namespace between Bootstrap and JQueryUI (tocify.js). As a result, I can't provide a live demo here. If you want to have a tooltip together with a floating TOC, you should use `popover` which has a very similar effect.
+
+
+
+## Popover Message
+The popover message looks very similar with tooltip but it can hold more contents. Unlike tooltip which can minimally work without you manually enable that module, you **have to** enable the `popover` module to get it work. The upper side is that there is no conflict between Bootstrap & JQueryUI this time, you can use it without any concern.
+
+```
+<script>
+$(document).ready(function(){
+    $('[data-toggle="popover"]').popover(); 
+});
+</script>
+```
+
+<script>
+$(document).ready(function(){
+    $('[data-toggle="popover"]').popover(); 
+});
+</script>
+
+```{r}
+popover_dt <- data.frame(
+  position = c("top", "bottom", "right", "left"),
+  stringsAsFactors = FALSE
+)
+popover_dt$`Hover over these items` <- cell_spec(
+  paste("Message on", popover_dt$position), # Cell texts
+  popover = spec_popover(
+    content = popover_dt$position,
+    title = NULL,                           # title will add a Title Panel on top
+    position = popover_dt$position
+  ))
+kable(popover_dt, "html", escape = FALSE) %>%
+  kable_styling("striped", full_width = FALSE)
+```
+
+## Links
+You can add links to text via `text_spec("Google", link = "https://google.com")`: `r text_spec("Google", link = "https://google.com")`. If you want your hover message to be more obvious, it might be a good idea to put a `#` in the `link` option.
+`text_spec("Hover on me", link = "#", popover = "Hello")`:
+`r text_spec("Hover on me", link = "#", popover = "Hello")`
+
+
 # Grouped Columns / Rows
 ## Add header rows to group columns
 Tables with multi-row headers can be very useful to demonstrate grouped data. To do that, you can pipe your kable object into `add_header_above()`. The header variable is supposed to be a named character with the names as new column names and values as column span. For your convenience, if column span equals to 1, you can ignore the `=1` part so the function below can be written as `add_header_above(c(" ", "Group 1" = 2, "Group 2" = 2, "Group 3" = 2)).
diff --git a/vignettes/awesome_table_in_pdf.Rmd b/vignettes/awesome_table_in_pdf.Rmd
index 18cb068..52da10b 100644
--- a/vignettes/awesome_table_in_pdf.Rmd
+++ b/vignettes/awesome_table_in_pdf.Rmd
@@ -65,9 +65,9 @@
 library(kableExtra)
 ```
 
-If you are using R Sweave, beamer, tufte or some customized rmarkdown templates, you can put the following meta data into the `yaml` section. If you are familar with LaTeX and you know what you are doing, feel free to remove unnecessary packages from the list. 
+If you are using R Sweave, beamer, R package vignette template, tufte or some customized rmarkdown templates, you can put the following meta data into the `yaml` section. If you are familar with LaTeX and you know what you are doing, feel free to remove unnecessary packages from the list. 
 
-```{yaml}
+```
 header-includes:
   - \usepackage{booktabs}
   - \usepackage{longtable}
@@ -85,7 +85,7 @@
 ## Plain LaTeX
 Plain LaTeX table looks relatively ugly in 2017.
 ```{r}
-kable(dt, format = "latex")
+kable(dt)
 ```
 
 ## LaTeX table with booktabs
@@ -198,6 +198,78 @@
   row_spec(3:5, bold = T, color = "white", background = "black")
 ```
 
+## Header Rows
+One special case of `row_spec` is that you can specify the format of the header row via `row_spec(row = 0, ...)`. 
+```{r}
+kable(dt, format = "latex", booktabs = T, align = "c") %>%
+  kable_styling(latex_options = "striped", full_width = F) %>%
+  row_spec(0, angle = 45)
+```
+
+
+
+# Cell/Text Specification
+Function `cell_spec` is introduced in version 0.6.0 of `kableExtra`. Unlike `column_spec` and `row_spec`, **this function is designed to be used before the data.frame gets into the `kable` function**. Comparing with figuring out a list of 2 dimentional index for targeted cells, this design is way easier to learn and use and it fits perfectly well with `dplyr`'s `mutate` and `summarize` functions. With this design, there are two things to be noted:
+* Since `cell_spec` generates raw `HTML` or `LaTeX` code, make sure you remember to put `escape = FALSE` in `kable`. At the same time, you have to escape special symbols including `%` manually by yourself
+* `cell_spec` needs a way to know whether you want `html` or `latex`. You can specify it locally in function or globally via the `options(knitr.table.format = "latex")` method as suggested at the beginning. If you don't provide anything, this function will output as HTML by default. 
+
+Currently, `cell_spec` supports features including bold, italic, monospace, text color, background color, align, font size & rotation angle. More features may be added in the future. Please see function documentations as reference. 
+
+## Conditional logic
+It is very easy to use `cell_spec` with conditional logic. Here is an example.
+```{r, message=FALSE, warning=FALSE}
+library(dplyr)
+mtcars[1:10, 1:2] %>%
+  mutate(
+    car = row.names(.),
+    # You don't need format = "latex" if you have ever defined options(knitr.table.format)
+    mpg = cell_spec(mpg, "latex", color = ifelse(mpg > 20, "red", "blue")),
+    cyl = cell_spec(cyl, "latex", color = "white", align = "c", angle = 45, 
+                    background = factor(cyl, c(4, 6, 8), 
+                                        c("#666666", "#999999", "#BBBBBB")))
+  ) %>%
+  select(car, mpg, cyl) %>%
+  kable("latex", escape = F, booktabs = T, linesep = "")
+```
+
+## Visualize data with Viridis Color
+This package also comes with a few helper functions, including `spec_color`, `spec_font_size` & `spec_angle`. These functions can rescale continuous variables to certain scales. For example, function `spec_color` would map a continuous variable to any [viridis color palettes](https://cran.r-project.org/web/packages/viridis/vignettes/intro-to-viridis.html). It offers a very visually impactful representation in a tabular format. 
+
+```{r}
+iris[1:10, ] %>%
+  mutate_if(is.numeric, function(x) {
+    cell_spec(x, "latex", bold = T, color = spec_color(x, end = 0.9),
+              font_size = spec_font_size(x))
+  }) %>%
+  mutate(Species = cell_spec(
+    Species, "latex", color = "white", bold = T,
+    background = spec_color(1:10, end = 0.9, option = "A", direction = -1)
+  )) %>%
+  kable("latex", escape = F, booktabs = T, linesep = "", align = "c")
+```
+
+In the example above, I'm using the `mutate` functions from `dplyr`. You don't have to use it. Base R solutions like `iris$Species <- cell_spec(iris$Species, color = "red")` also works. 
+
+## Text Specification
+If you check the results of `cell_spec`, you will find that this function does nothing more than wrapping the text with appropriate HTML/LaTeX formatting syntax. The result of this function is just a vector of character strings. As a result, when you are writing a `rmarkdown` document or write some text in shiny apps, if you need extra markups other than **bold** or *italic*, you may use this function to `r text_spec("color", color = "red")`, `r text_spec("change font size ", font_size = 16)` or `r text_spec("rotate", angle = 30)` your text. 
+
+An aliased function `text_spec` is also provided for a more literal writing experience. The only difference is that in LaTeX, unless you specify `latex_background_in_cell = FALSE` (default is `TRUE`) in `cell_spec`, it will define cell background color as `\cellcolor{}`, which doesn't work outside of a table, while for `text_spec`, the default value for `latex_background_in_cell` is `FALSE`.
+
+```{r}
+sometext <- strsplit(paste0(
+  "You can even try to make some crazy things like this paragraph. ", 
+  "It seems to be a useless feature at this moment but who cares. ", 
+  "It is so fun to play with color that I can't stop. ;D"
+), " ")[[1]]
+text_formatted <- paste(
+  text_spec(sometext, "latex", color = spec_color(1:length(sometext), end = 0.9),
+            font_size = spec_font_size(1:length(sometext), begin = 5, end = 20)),
+  collapse = " ")
+
+# To display the text, type `r text_formatted` outside of the chunk
+```
+`r text_formatted`
+
 # Grouped Columns / Rows
 ## Add header rows to group columns
 Tables with multi-row headers can be very useful to demonstrate grouped data. To do that, you can pipe your kable object into `add_header_above()`. The header variable is supposed to be a named character with the names as new column names and values as column span. For your convenience, if column span equals to 1, you can ignore the `=1` part so the function below can be written as `add_header_above(c(" ", "Group 1" = 2, "Group 2" = 2, "Group 3" = 2)).
@@ -207,7 +279,7 @@
   add_header_above(c(" " = 1, "Group 1" = 2, "Group 2" = 2, "Group 3" = 2))
 ```
 
-In fact, if you want to add another row of header on top, please feel free to do so. Also, in kableExtra 0.3.0, you can specify `bold` & `italic` as you do in `row_spec()`.
+In fact, if you want to add another row of header on top, please feel free to do so. Also, since kableExtra 0.3.0, you can specify `bold` & `italic` as you do in `row_spec()`.
 ```{r}
 kable(dt, format = "latex", booktabs = T) %>%
   kable_styling(latex_options = "striped") %>%
diff --git a/vignettes/use_kableExtra_with_formattable.Rmd b/vignettes/use_kableExtra_with_formattable.Rmd
new file mode 100644
index 0000000..641fe78
--- /dev/null
+++ b/vignettes/use_kableExtra_with_formattable.Rmd
@@ -0,0 +1,63 @@
+---
+title: "Use kableExtra with formattable"
+author: "Hao Zhu"
+date: "`r Sys.Date()`"
+output: html_document
+vignette: >
+  %\VignetteIndexEntry{Use kableExtra with formattable}
+  %\VignetteEngine{knitr::rmarkdown}
+  %\VignetteEncoding{UTF-8}
+---
+
+I know you love `formattable`'s `color_tile` and `color_bar`. I do too. In my mind, these two features are among the best visualization methods in a tabular format. You may wonder if it's possible use it together with `kableExtra` so you can have a nested table with awesome presentation at the same time. Here is how. 
+
+```{r, message=FALSE, warning=FALSE}
+library(knitr)
+library(kableExtra)
+library(formattable)
+library(dplyr)
+```
+
+```{r}
+mtcars[1:5, 1:4] %>%
+  mutate(
+    car = row.names(.),
+    mpg = color_tile("white", "orange")(mpg),
+    cyl = cell_spec(cyl, "html", angle = (1:5)*60, 
+                    background = "red", color = "white", align = "center"),
+    disp = ifelse(disp > 200,
+                  cell_spec(disp, "html", color = "red", bold = T),
+                  cell_spec(disp, "html", color = "green", italic = T)),
+    hp = color_bar("lightgreen")(hp)
+  ) %>%
+  select(car, everything()) %>%
+  kable("html", escape = F) %>%
+  kable_styling("hover", full_width = F) %>%
+  column_spec(5, width = "3cm") %>%
+  add_header_above(c(" ", "Hello" = 2, "World" = 2))
+```
+
+Here is a little bit more explanation. Both `formattable::color_tile` and `formattable::color_bar` returns a function object which can take a numeric vector. That's why you can put things like `(mpg)` after `color_tile("white", "orange")` as you can see in the `mutate` function. This way of using the function may look a little odd but is totally valid (, I think :P).
+
+Also, if you are using it in this way, make sure you put `escape = F` in `kable`. 
+
+On the other hand, `cell_spec()` is a new function in `kableExtra()` to format cells _**before you pipe the table into `kable`**_. Note that you can either specify format (`html` or `latex`) in function or do that via `options(knitr.table.format)` so you don't need to do it everytime. Please refer to the package vignette for details. 
+
+<script>
+$(document).ready(function(){
+    $('[data-toggle="tooltip"]').tooltip(); 
+});
+</script>
+
+```{r}
+iris[1:10, ] %>%
+  mutate(
+    Species = cell_spec(Species, color = spec_color(1:10, option = "A"), link = "#",
+                        tooltip = paste0("Sepal Length: ", Sepal.Length))
+  ) %>%
+  mutate_if(is.numeric, function(x){
+    cell_spec(x, "html", color = spec_color(x), font_size = spec_font_size(x), bold = T)
+  }) %>%
+  kable("html", escape = F, align = "c") %>%
+  kable_styling("condensed", full_width = F)
+```