Issues changing colours for form fields and borders

Hi there, i’m having lots of trouble using CSS to change the default colour of the form field text and also the border colours… the light grey needs to be darker. I understand UM removed the colour customisation features a few years ago, but just having trouble narrowing down which css properties I need to update.
Have tried adding the below custom CSS but it’s not working:
.um-field-label {color: #000000 !important;}
.um-form-field{
border: 1px solid #000000 !important;}
Can anyone provide the css I need to use for this?
Thanks,
Trudi