Request: Minimal working example for styles about xlsx

[qrilka]

Please take a look at this thing - https://gist.github.com/qrilka/ffd9fe984e3a50fa1b0bb6c5bcd7859c
xlsx is sometimes a bit odd, for example - take a look at the definition of minimalStyleSheet , you need to have some defaults in your stylesheet, and the main thing is using foreground color for a pattern not a background one.

[deemp]

@qrilka, thank you so much! When running your example, I got (3, 2) painted grey. This behavior should be related to this issue.

[qrilka]

PR will be more than welcome if you could find out the details behind this behavior