Create a subtheme Drupal 7
First of all, create a new directory in the sites theme folder to add the custom theme.
Create the .info file, aside the mandatory name and core properties, and the recommended desription property, add the base theme property.
name = Custom subtheme desription = A custom subtheme for training purposes core = 7.x base theme = bartik
The custom theme can be activated on the /admin/appearance page. As you can see in the image below, the themes screenshot is taken from the base theme.
Enable and set default to see the custom theme in action.
The default Bartik theme doesn't need to be enabled, disable it to keep your Drupal enabled themes array clean.
Now, as seen in the image below, the layout from the new theme is the same as Bartik, however, the logo is missing.
Every Drupal 7 theme needs to have a logo. In this example, the default Bartik logo is copied from the core themes directory into the subtheme directory.
Once the logo is added and the page is refreshed, a set of notices are printed referring to undefined indexes in the Bartik page template.
Regions are not inherited in the subtheme. To inherit the regions from the base theme, copy the regions properties to the .info file of the subtheme.
name = Custom subtheme desription = A custom subtheme for training purposes core = 7.x base theme = bartik regions[header] = Header regions[help] = Help regions[page_top] = Page top regions[page_bottom] = Page bottom regions[highlighted] = Highlighted regions[featured] = Featured regions[content] = Content regions[sidebar_first] = Sidebar first regions[sidebar_second] = Sidebar second regions[triptych_first] = Triptych first regions[triptych_middle] = Triptych middle regions[triptych_last] = Triptych last regions[footer_firstcolumn] = Footer first column regions[footer_secondcolumn] = Footer second column regions[footer_thirdcolumn] = Footer third column regions[footer_fourthcolumn] = Footer fourth column regions[footer] = Footer
Remember, a .info file is cached. To let Drupal know about the new regions, clear the cache.