Support for fixed first column in horizontal-scrollable tables

[jimbobmcgee]

I have added a gist (https://gist.github.com/jimbobmcgee/edd734e4bfc3eb7c90ae7ef001f8b756) for the extra CSS needed to allow a table with table-scroll to have a first column which remains on screen during the scroll. The colours are just taken from the Spectre docs page, but work for striped and hovered tables, too.

I'm not a SASS guy, so I am not about to meddle with any preprocessor, but if you want to incorporate it within your SASS rules so it better respects screen sizes, colours, etc., please feel free.

It also might be better to target a specific class, e.g. table-sticky, which is easily achievable.