What if my embed note contains other h5 headers? 
My solution is:
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h1,
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h2,
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h3,
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h4,
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h5,
.markdown-preview-view.clean-embeds .markdown-preview-view > div.markdown-preview-sizer.markdown-preview-section > div:nth-child(2) > h6 {
display: none
}
But it’s not perfect because it also hides the message when header was not found like this:
