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I agree with the other answers, but believe 100% your header should be above body content. The way I explain it to my clients is the header is a promise of what is to come. You wouldn't pick up a book without reading the title would you? Or know if it is in your own language? The header is also the position to tell the SERP's what your entire site is about, look this site is about "such and such" with the "author tag so and so", written to answer "these questions" and you will find ALL that and more in the content. Body above the header was a trick used years ago in SEO to force feed our intentions on the search engine, now we just politely introduce our page and let them browse the content.