Using XML file to order the loading of the CSS files
In Global folder
of you theme file structure you can place as many CSS files as you
want, but if you need to load them in specific order, you must describe
them in cssLoadOrder.xml. The file must be placed in Global folder and it has the following content:
File: ~/App_Data/Sitefinity/WebsiteTemplates/YourTemplate/App_Themes/MyTheme/Global/cssLoadOrder.xml
<?xml version="1.0" encoding="utf-8" ?>
<cssFiles>
<file>Reset.css</file>
<file>Layout.css</file>
<file>Colors.css</file>
<file>Font_styles.css</file>
</cssFiles>
The sequence of loading the files will be according to their arrangement in cssLoadOrder.xml.