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Many .NET software developers use Visual Studio, or its free express version Visual Web Developer, to create and edit CSS for Sitefinity. You could also use other IDEs, such as DreamWeaver or even NotePad to create CSS. Once the CSS is created, you put it inside a folder and copy it to the App_Themes directory of Sitefinity. For more info on working with CSS and our tool, please read Designing with Sitefinity
in our Developer Manual
Feel free to contact us if you have any questions.
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