No version of Gmail supports the <style> , creating media queries that cannot be built into Gmail inefficiently.
If you need something more consistent between customers, most people come with a liquid layout. However, this pretty much limits you to the design of individual columns. You can set the multimedia request to the maximum width so that it looks like a regular 600px mailbox in Outlook, but resizes for all devices smaller than 600 pixels.
Hope this helps.
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