Reactive coloring in DT table - shiny

Question

Need help. Below is the application. ColB is to be colored based on numbers in ColA. Below is the condition table
Just to brief : if ColB is 2, So it is lesser than 6 (12/2), it should be red and similarly for others. I tried to build the code myself and came up with below . But looks like there is some issue in the code . I have attached the output also below and the logic is not working properly.
---
title: "Untitled"
runtime: shiny
output:
flexdashboard::flex_dashboard:
orientation: columns
vertical_layout: fill
---
```{r setup, include=FALSE}
library(flexdashboard)
library(DT)
```
```{r}
tab1 <- data.frame(ColA = c(12,34,45,56), ColB = c(2,32,30,56))
```
Column {data-width=650}
-----------------------------------------------------------------------
### Chart A
```{r}
DT::DTOutput("table1")
output$table1 <- DT::renderDT(
datatable(tab1))
```
Below is the output I got
So As per the code, the highlighted arrows are showing color.
First Arrow (Supposed to be red but it is showing as Yellow)
Second Arrow (Supposed to be Yellow but it is showing as Green)
Note : ColB is randomly generated and you may not see these numbers when you run it. But you observe randomly, this issue you will find for sure when you run as well. Not sure what is wrong in the code . Below is the code for your reference

Answer 1

You could use formatStyle from DT (link):
---
title: "Untitled"
runtime: shiny
output:
flexdashboard::flex_dashboard:
orientation: columns
vertical_layout: fill
---
```{r setup, include=FALSE}
library(flexdashboard)
library(tidyverse)
library(DT)
```
```{r}
tab1 <- data.frame(ColA = c(12,34,45,56), ColB = c(2,32,30,56)) %>%
dplyr::mutate(backgroundColB = case_when(
ColA==ColB ~ 1,
ColA/2>ColB ~ -1,
ColA/2<ColB ~ 0
))
```
Column {data-width=650}
-----------------------------------------------------------------------
### Chart A
```{r}
DT::DTOutput("table1")
output$table1 <- DT::renderDT(
datatable(tab1, options=list(columnDefs = list(list(visible=FALSE, targets=2)))) %>%
formatStyle('ColB', "backgroundColB",
backgroundColor = styleInterval(c(-.5,.5), c("red","yellow","green") ))
)
```