vaadin
[lumo] Deprecate tertiary text color
The current tertiary text color has a contrast of 2.92 :1 on the base color (white), which does not meet any accessibility requirements. The usefulness of this color property is questionable.
The only place I remember it being used at the moment is in date picker, for the week day names and week numbers. That’s a poor design decision on my part.
I propose that we deprecate the tertiary text color, and remove it in the next major version of Lumo.
Technically, we could map the property by default to the secondary text color, to improve accessibility. Not sure if there’s a way to give any deprecation warning about this, if some custom CSS is using it?
Added this to the list of breaking changes. I don't think there is a way to give a warning without using a tool like Stylelint.
Well, we can at least mark it deprecated in the documentation and in code, to discourage its use.
Once date picker styles are fixed (#2727), this color property is only used for icons: Grid sort icon, Context Menu and Menu Bar sub-menu indicators, and Tabs scroll button icons.
I suggest we still deprecate the text color, in add another property that reflects the purpose better, that this property is mainly used for graphical elements and is guaranteed to have 3:1 contrast ratio with the default background colors.
We might want to consider #2738 together with this issue. The tertiary color currently has 3:1 contrast, and might be suitable for disabled text instead.
I added information to the documentation about the contrast ratios of these (https://github.com/vaadin/docs/commit/ff6d470a9e11a868017acd3fa4b0c08111f5a605#diff-25e5c1a20a8445e4e396bac79f0e31519cbd4f49707245793c382979e6fe8c0d), and discouraged the use of this property for text elements.
Another reason for deprecating/removing this color, and using some other color for the few places where it’s used: https://github.com/vaadin/web-components/issues/115