Text color in the report

[ratelChief]

why some text is white and other is black? or it's just a visual effect for better readability?

[btd]

Yes, it is for better readability. See there https://github.com/btd/rollup-plugin-visualizer/blob/master/src/treemap/color.ts#L19C20-L19C20
It checks luminance of background and tries to select either white or black.