1) The HTML and CSS in our themes all should be valid. There may be minor things here and there that may not pass a W3C validation test but they are minor. For example, iframe code from Twitter or Facebook may create a validity error but we have no way to work around that. We use the code we receive from those services.
Do you have specific examples of code in our product that give you concern?
2) We understand your concern but it's truly undecided whether valid HTML and CSS help with
SEO. We appreciate that you may prefer to err on the side of caution. We have thousands of customers that have used our products successfully with
SEO in mind. Not only is the code valid but WordPress is great for
SEO. Even more, our founder has spent years in the
SEO/SEM industry and has applied any principles learned there to our themes.
3) We regularly test in all major browsers on Windows and OSX to assure performance and proper display.
We hope this information helps. Thanks.
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