A cascading style sheet (CSS) file is used to control the formatting of the output of the HTML export. You can edit style sheets using any standard text editor or HTML-authoring tool.

The HTML Export option has two built-in style sheets:

By default, the stylesheet is embedded in the HTML output, but you can export the stylesheet separately. This creates the stylesheet (called mrTables Default.css or mrTables Black and White.css) in the output folder. You can then change it as required.

Alternatively, you can create your own stylesheet, and use the CustomCss Export property to specify the stylesheet to use. You might find it easier to begin by copying the default stylesheet. If you use a custom stylesheet it must be in the output directory: that is, you cannot embed a custom stylesheet.

When you subsequently export to the same location, the stylesheet is not overwritten unless you set the OverwriteOutput export property to True. (By default this property is set to False.). This means that you can make changes to the stylesheet and your changes will be preserved the next time you export to the same output folder.

Suppose you want to amend the Black and White style sheet to show the Left Header annotation in color, a larger size, and bold, and to format the cell contents that show the sum of a numeric variable in the same color and italics. In addition, you want to highlight the horizontal side axis text by changing the font color, and also the background color of the cell and the side indent cell. You could do this as follows:

Here is a table of Age by Gender showing the sum of the visits variable exported using the amended style sheet: