Colour contrast readOnly and placeholder text

[dhinrichs-scottlogic]

Feature Request

Description

Ensure all color contrast passes, including disabled buttons, readOnly fields (e.g. config inputs) and placeholder text (e.g. chat input)

• adjusted the --main-input-inactive-text-colour to pass but be less close to black
• adjusted the --level-button-colour-disabled colour to provide better contrast (it technically passed before because the text is bold, but just nudging it to also pass 4.5:1).
• Added placeholder pseudo selector to css to adjust textinput placeholder text colour

Screenshots

Additional context

Colour contrast issues for placeholder text are easily missed by automated tools, but colour contrast ratios should still pass for placeholder text and inactive input text.

Acceptance criteria

GIVEN text/number inputs and buttons
WHEN they are disabled, readonly or have placeholder text
THEN the text to background contrast ratio is at least 4.5:1