Hi there,
you can use some CSS like this to add a background color with some padding:
.page-hero .mailster-form {
padding: 20px;
box-sizing: border-box;
background-color: #ccc;
}
If you want greater styling control, and the header element doesn’t require any Dynamic content such as Post Title or Post meta – you may want to use the Block Element instead:
https://docs.generatepress.com/article/block-element-overview/
You can hook in custom built Blocks using GenerateBlocks in the after_header
hook to position it where the Header Element appears.