>> CSS1 file

CSS1 file format description

Many people share .css1 files without attaching instructions on how to use it. Yet it isn’t evident for everyone which program a .css1 file can be edited, converted or printed with. On this page, we try to provide assistance for handling .css1 files.

1 filename extension(s) found in our database.

.css1 - CSS Backup

The CSS1 data files are related to Mozilla Firefox. CSS1 file is a CSS Backup. Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g. fonts, colors, spacing) to Web documents.

Mozilla Firefox
Data files
- / -
CSS Backup related extensions:
Microsoft Word 5 for Mac Custom Dictionary Data
Adobe PageMaker for Mac Dictionary Data
Intuit Quicken 5 for Windows Data
UltraMixer File Archive
UltraMixer Preset Data
UltraMixer Sample Bank Data

Naturally, other applications may also use the .css1 file extension. Even harmful programs can create .css1 files. Be especially cautious with .css1 files coming from an unknown source!

Can't open a .css1 file?

When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize a filename extension, you receive the following message:

Windows can't open this file:


To open this file, Windows needs to know what program you want to use to open it. Windows can go online to look it up automatically, or you can manually select one from a list of programs that are installed on your computer.

To avoid this error, you need to set the file association correctly.

The .css1 file extension is often given incorrectly!

According to the searches on our site, these misspellings were the most common in the past year:

cs1, css, ss1

Is it possible that the filename extension is misspelled?

Similar file extensions in our database:

Scream Center for Seismic Studies Data
Cygnus MK Data Logger Single Record
Sinar CaptureShop RAW Image
Cascading Style Sheets

Operating systems currently supports the following operating systems:

Windows XP/Vista, Windows 7/8, Windows 10, CentOS, Debian GNU/Linux, Ubuntu Linux, FreeBSD, Mac OS X, iOS, Android

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If you have useful information about the .css1 file format, then write to us!