SharePoint Designer file
File type: Various data file
A .spdesigncss file is a SharePoint Designer file associated with the design of Microsoft SharePoint sites and web pages.
It belongs to Office SharePoint Designer, Microsoft's Windows application for creating and modifying SharePoint sites and their pages.
File type category:
Various data file
Date updated: September 27, 2026
The .spdesigncss file extension identifies a file used by Office SharePoint Designer. It is associated with the CSS and other design information that SharePoint Designer uses when working with SharePoint pages.
Office SharePoint Designer is a Microsoft Windows HTML editor and web design program for creating and modifying Microsoft SharePoint sites and web pages. The file forms part of the site's design resources rather than being a general-purpose document.
Office SharePoint Designer is a legacy application and is no longer actively developed. Files in this format may therefore be encountered in older SharePoint projects or sites.
Open a .spdesigncss file with Office SharePoint Designer on Microsoft Windows. If the file belongs to a SharePoint site, opening or editing the associated site in SharePoint Designer may be necessary for the file to be interpreted correctly.
A .spdesigncss file is not normally converted as a standalone document. Its design information is intended to be used with the related SharePoint site and Office SharePoint Designer.
For a migration, use the associated site in a compatible SharePoint environment rather than treating the file as a standalone document.
Software applications that handle other tasks involving spdesigncss files:
Microsoft Windows
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