Contact form dropdown colours

Hi, 

I created a site for a client, and the background on dropdown in the contact form looks normal for me, but for her the background is light red with dark red text. What would cause this difference and how do I change it?

Thank you.

Can you share link to page where you use contact form?

Hi, sure: 

https://www.radhapatel.co.uk/contact

It shows this to me

Do you use Safari/Mac? Sometimes Form dropdown will inherit style from Mac

You can also use this code to Website Tools > Custom CSS

div.form-block select option {
    background-color: #ececec !important;
    color: #000 !important;
}