green rectangular box appears on my contact form after i submit

Hi there after I fill out the contact form and hit the submit button an green outline of a rectangular box appears around the contact form entry area, any ideas why. The actual form is functioning fine and emails are being sent just wondered if you have seen or heard of this anywhere else.

thanks again

Hello @dunster72,

Please use this CSS code to fix the issue:

div.wpcf7-mail-sent-ok {
    border: none;
    color: #fff;