Change background color of my post 'submit' page

Site URL: https://wildwomb.space/freemeditation

Hello

I want to update the code of this page (see image) so I can change the background color to #dd8f9e. Any advice much appreciated. Thank you

my current code is:

<style>
  .form-title {
    visibility: hidden;
}
  .form-title:before {
    visibility: visible;
    content: "This FREE audio guided-meditation will help you build peace & connection with your feminine energy. Where should I send it?";
    font-size: 20px;font-family: 'future pt', sans-serif;

    
}

</style>

Add to Home > Design > Custom CSS

.lightbox-content input.button {
    background:  #dd8f9e !important;
}