This way it's possible to customize these colors by just changing a
variable.
The code is now quite a bit hacky; since I'm not an expert in color
design, I didn't want to change the colors we were using in case it made
the application have less appeal.
If slightly changing these colors isn't a problem, we could use
Foundation's defaults to simplify the code, maybe just changing the
`$table-color-scale` variable.
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