.wp-block-template-part__header,
.wp-site-blocks > header { 
  position: sticky; 
  top: 0; 
  z-index: 1000; 
  background:#fff; 
}

header.is-sticky div.wp-block-group {
	background: #c0d3ab;
}

body.admin-bar .wp-block-template-part__header,
body.admin-bar .wp-site-blocks > header { 
  top: 32px; 
}