The cell_fill() function

Use exibble to create a gt table. Add styles with tab_style() and the cell_fill() helper function.

exibble |>
  dplyr::select(num, currency) |>
  gt() |>
  fmt_number(
    columns = c(num, currency),
    decimals = 1
  ) |>
  tab_style(
    style = cell_fill(color = "lightblue"),
    locations = cells_body(
      columns = num,
      rows = num >= 5000
    )
  ) |>
  tab_style(
    style = cell_fill(color = "gray85"),
    locations = cells_body(
      columns = currency,
      rows = currency < 100
    )
  )

num	currency
0.1	50.0
2.2	17.9
33.3	1.4
444.4	65,100.0
5,550.0	1,325.8
NA	13.3
777,000.0	NA
8,880,000.0	0.4