Hey Again, Hope you had a Positive Weekend, 

Did you try the Form Styling Options in the Salient Theme Options Panel: 

Click To Open Larger Image.

Thanks 

Hey,
Please provide the page URL so I may write up the custom CSS for this request.
Thanks

Add this into the Custom CSS box in your Salient Theme Options panel (We write all Custom CSS in the Live Browser to ensure accuracy. If you cannot see any changes, make sure there is no red cross in the Custom CSS Box as any syntax error would cause all CSS under that line of code to not show up on the Frontend):

.wpcf7-form p span input::placeholder {
    color: #fff !important;
    opacity: .5 !important;
}
.wpcf7-form p span input {
    color: #fff !important;
}

Thanks