Theme: Use the Excel 2023/Aptos theme
An example of changing the default theme for a workbook using the
rust_xlsxwriter library. The example uses the Excel 2023 Office/Aptos theme.
Note that the default font has changed to "Aptos Narrow (body) 11".
Image of the output file:

Code to generate the output file:
// SPDX-License-Identifier: MIT OR Apache-2.0
//
// Copyright 2022-2025, John McNamara, jmcnamara@cpan.org
//! Example of changing the default theme for a workbook using the
//! `rust_xlsxwriter` library. The example uses the Excel 2023 Office/Aptos
//! theme.
use rust_xlsxwriter::{Workbook, XlsxError};
fn main() -> Result<(), XlsxError> {
let mut workbook = Workbook::new();
// Use the Excel 2023 Office/Aptos theme in the workbook.
workbook.use_excel_2023_theme()?;
// Add a worksheet to the workbook.
let worksheet = workbook.add_worksheet();
// Write some text to demonstrate the changed theme.
worksheet.write(0, 0, "Hello")?;
// Save the workbook to disk.
workbook.save("theme_excel_2023.xlsx")?;
Ok(())
}