ORC External Candidate Portal Change field background color

Hi Experts,

We have had a number of candidates complain that they cannot clearly see the "I agree with the terms and conditions" checkbox when applying for a job via the external candidate portal.

Please refer to the attached screen shot.

What I would like to know, is how do we modify the back color or border color of:
text box fields
dropdown fields
option buttons
and most importantly checkboxes

This issue is impacting the accessibility for some of our candidates to apply for roles with ACC.

Any help greatly appreciated.

Thanks