.wp-block-heading.has-background, 
.wp-block-heading.has-background h2, 
.wp-block-heading.has-background h3, 
.wp-block-heading.has-background h4, 
.wp-block-heading.has-background h5, 
.wp-block-heading.has-background h6 {
    padding: 0 !important;
}