The placement of content if part of the Design process. Putting contact information and stuff like that in your header is part of teh Design process to I believe
I would also mean that the content is optimized for the web, such as the text focusing on a specific keyword etc.
“Design” and SEO have nothing to do with each other…
SEO is about content - words - what you say and how you say it
Design is about visual appearance, usability and function