This tutorial describes how to add a custom CSS file in Magento.
In order to add a custom CSS file, you should perform the following changes:
Upload your custom CSS file to the server. The directory is as follows: skin/frontend/tm_themes/themeXXX/css:
In order to make the CSS rules work, one should link the file to the template. Please navigate to app/design/frontend/tm_themes/themeXXX/layout and edit local.xml file:
Insert the following piece of code somewhere among the similar ones (it basically contains the relative path to your file):
Save the changes.
Feel free to check the detailed video tutorial below: