CSS1 file format description

Many people often share .css1 files without providing instructions on how to use them. This can make it difficult for users to determine which program is compatible for editing, converting, or printing .css1 files. To address this issue, we have created this page to offer assistance and guidance on handling .css1 files. We provide information on compatible software, editing instructions and conversion options to help users effectively interact with .css1 files.

Our aim is to simplify the process and promote seamless use of the .css1 file format.

1 filename extension(s) found in our database.

.css1 - CSS Backup

The CSS1 data files are related to Mozilla Firefox. The 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:
ASwin Shared Database
XTND Filter
RFM Covariate Table
MariaDB InnoDB Undo Log
QlikView Table Data
Steam Client GUI Resources 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!

Based on searches conducted on our site in the past year, we have compiled a list of the most common misspellings. These frequent misspellings can cause confusion and hinder search accuracy. By providing this list, we aim to assist users in finding the correct information more easily and improving their overall search experience 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?

There is a possibility that the .css1 filename extension is misspelled. To assist users in identifying potential errors, we provide a list of similar file extensions in our database.

Filename extensions similar to .css1:

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

Operating systems

At DataTypes.net, we strive to provide a seamless user experience by ensuring compatibility with a wide range of operating systems. The following is a comprehensive list of the operating systems currently supported by DataTypes.net:

Windows XP/Vista, Windows 7/8/10, Windows 11, CentOS, Debian GNU/Linux, Ubuntu Linux, FreeBSD, macOS, Mac OS X, iOS, Android

If you find the information on this page useful, please feel free to link to this page.


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

DataTypes.net >> CSS1 file