* Strong knowledge of CSS2 or/and CSS3!
* Use a browser with developer tools to easily find CSS classes you want to modify.
### Copy Time!
Copy the default folder from ui/resource/theme and rename to _newtheme_ for exemple.
### Change path to theme
In the new folder, the file **theme.inc** show where CSS, icons and flag are loaded from.
You must change all paths to include the new theme name.
First, we suggest to modify the preview image **preview_theme.gif** to see easily your new theme in settings page.
Now your you can modify css files. You must use the web developer tools in your browser (key F12 by default) to select the elements you want to modify.
With the developer tools, you can live edit your CSS files and have an instant preview of your changes. Once you're fine with the changes, you have to report them back to the source files.