HTML Validation
HTML Guides for office
Learn how to identify and fix common HTML validation errors flagged by the W3C Validator — so your pages are standards-compliant and render correctly across every browser. Also check our Accessibility Guides.
An invalid CSS property is being used. Properties starting with mso- are commonly defined by Microsoft products like Office and Outlook.
These properties, like mso-spacerun, mso-fareast-font-family, mso-bidi-font-weight, mso-margin-bottom-alt, mso-margin-top-alt and others starting with mso- are not standard CSS properties.
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