CSS resets for email are either general resets or client-specific resets. General resets give all email clients and browsers a common base to work on. Client-specific resets target some of the quirks inherent in select email clients.
A CSS reset like the one below can be placed in an email's <style> tag and does not have to be inlined.
<style>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Hello!</title> <style> /* Remove spaces around the email design added by some email clients. */ html, body { margin: 0 auto !important; padding: 0 !important; height: 100% !important; width: 100% !important; } /* Stops email clients resizing small text. */ * { -ms-text-size-adjust: 100%; -webkit-text-size-adjust: 100%; } /* What is does: Centers email on Android 4.4 */ div[style*="margin: 16px 0"] { margin:0 !important; } /* Stops Outlook from adding extra spacing to tables. */ table, td { mso-table-lspace: 0pt !important; mso-table-rspace: 0pt !important; } /* Fixes webkit padding issue. Fix for Yahoo mail table alignment bug. Applies table-layout to the first 2 tables then removes for anything nested deeper. */ table { border-spacing: 0 !important; border-collapse: collapse !important; table-layout: fixed !important; margin: 0 auto !important; } table table table { table-layout: auto; } /* Uses a better rendering method when resizing images in IE. */ img { -ms-interpolation-mode:bicubic; } /* A work-around for iOS meddling in triggered links. */ .mobile-link--footer a, a[x-apple-data-detectors] { color:inherit !important; text-decoration: underline !important; } </style> </head> <body> <!-- Email Content --> </body> </html>