Input text invisible from iphone

Hello,
From iPhone Safari the plugin looks correct when loaded with page, but once I click on input field, the screen goes white and text is also white.

I have found no way of setting the text colour to black so someone can see what they’re typing. Can you please tell me how to do this?

I have tried ‘Inspect element’ using the iphone safari but it is showing the text colour black which is correct for page but clearly not what is happening when I try to type into that.

Many thanks!

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