Malichimp signup form glitch

I have created a new page and inserted the embedded form builder code provided by Mailchimp to place a signup form into the page but the text boxes automatically appear red once the code is inserted without entering any data as shown below.

The URL is gloucesterguildhall.co.uk. The website uses 7.0. The URL slug is /newsletter.

Can anyone advise why this is?

Add to Design > Custom CSS

div#mc_embed_signup_scroll input {
    background: white !important;
}