With the tab_style() function we can target specific cells and apply styles
to them. This is best done in conjunction with the helper functions
cell_text(), cell_fill(), and cell_borders(). At present this function
is focused on the application of styles for HTML output only (as such, other
output formats will ignore all tab_style() calls). Using the aforementioned
helper functions, here are some of the styles we can apply:
the background color of the cell (cell_fill(): color)
the cell's text color, font, and size (cell_text(): color, font,
size)
the text style (cell_text(): style), enabling the use of italics or
oblique text.
the text weight (cell_text(): weight), allowing the use of thin to
bold text (the degree of choice is greater with variable fonts)
the alignment and indentation of text (cell_text(): align and
indent)
the cell borders (cell_borders())
tab_style(data, style, locations)An object of class gt_tbl.
A table object that is created using the gt() function.
a vector of styles to use. The cell_text(), cell_fill(), and
cell_borders() helper functions can be used here to more easily generate
valid styles. If using more than one helper function to define styles, all
calls must be enclosed in a list(). Custom CSS declarations can be used
for HTML output by including a css()-based statement as a list item.
the cell or set of cells to be associated with the style.
Supplying any of the cells_*() helper functions is a useful way to target
the location cells that are associated with the styling. These helper
functions are: cells_title(), cells_stubhead(),
cells_column_spanners(), cells_column_labels(), cells_row_groups(),
cells_stub(), cells_body(), cells_summary(), cells_grand_summary(),
cells_stub_summary(), cells_stub_grand_summary(), cells_footnotes(),
and cells_source_notes(). Additionally, we can enclose several
cells_*() calls within a list() if we wish to apply styling to
different types of locations (e.g., body cells, row group labels, the table
title, etc.).
Use exibble to create a gt table. Add styles that are to be applied
to data cells that satisfy a condition (using tab_style()).
exibble %>%
dplyr::select(num, currency) %>%
gt() %>%
fmt_number(
columns = c(num, currency),
decimals = 1
) %>%
tab_style(
style = list(
cell_fill(color = "lightcyan"),
cell_text(weight = "bold")
),
locations = cells_body(
columns = num,
rows = num >= 5000
)
) %>%
tab_style(
style = list(
cell_fill(color = "#F9E3D6"),
cell_text(style = "italic")
),
locations = cells_body(
columns = currency,
rows = currency < 100
)
)

Use sp500 to create a gt table. Color entire rows of cells based on
values in a particular column.
sp500 %>%
dplyr::filter(
date >= "2015-12-01" &
date <= "2015-12-15"
) %>%
dplyr::select(-c(adj_close, volume)) %>%
gt() %>%
tab_style(
style = cell_fill(color = "lightgreen"),
locations = cells_body(rows = close > open)
) %>%
tab_style(
style = list(
cell_fill(color = "red"),
cell_text(color = "white")
),
locations = cells_body(rows = open > close)
)

Use exibble to create a gt table. Replace missing values with the
sub_missing() function and then add styling to the char column with
cell_fill() and with a CSS style declaration.
exibble %>%
dplyr::select(char, fctr) %>%
gt() %>%
sub_missing() %>%
tab_style(
style = list(
cell_fill(color = "lightcyan"),
"font-variant: small-caps;"
),
locations = cells_body(columns = char)
)

2-10
cell_text(), cell_fill(), and cell_borders() as helpers for
defining custom styles and cells_body() as one of many useful helper
functions for targeting the locations to be styled.
Other part creation/modification functions:
tab_caption(),
tab_footnote(),
tab_header(),
tab_info(),
tab_options(),
tab_row_group(),
tab_source_note(),
tab_spanner_delim(),
tab_spanner(),
tab_stub_indent(),
tab_stubhead(),
tab_style_body()