This is an example of a ReactJS Pivot Grid with custom style of the grid cells depending on their current value. You can change the rendering of any cell, row or column and insert your own HTML content by implementing the itemsRenderer and cellsRenderer functions. In this case, the custom code simply chooses among five predefined colors and sets the backgroundColor property of the cell content. This color customization is applied only to the cells with 'Sum' aggregation function. You can change the code of the itemsRenderer and cellsRenderer functions inside the React app.js and implement your own customization logic using standard HTML and CSS. Make sure that the implementation of the custom rendering functions is as efficient as possible. The functions will be called multiple times due changes in the internal state of the pivot grid like scrolling, drill down or selection change. The pivot grid component is optimized to cache the content of the pivot cells, rows and columns and the custom functions will be called only when needed.