The themes consist of a set of template files (.tpl.php), style sheets (.css) and other files such as images and Javascript files. We will begin this unit by analyzing this file structure.
The Initial Level makes a brief introduction to the modification of the aspect of a subject through the CSS style sheets. At this level we go a step further toward the modification of topics. This, however, is not the final step. We include an introduction to Web publishing with HTML; which is something fundamental if we want to have greater control over the final design of the site. We must not be afraid to modify the style sheets or HTML code because it is not a question of programming languages but simply of markup languages or labelling which is simpler to use.
Drupal templates mix HTML with PHP and so we must use both languages well to avoid the site "break". Whenever we are going to modify the theme of the site, we have to make sure that we first have activated a different administration theme.