Theming Drupal with multi class selectors

sometimes it's useful to check for the existence of two classes in an element before applying a style to it. For example, if you have a front page that has a different width sidebar than an interior page, you could use a separate page-front.tpl.php file, kind of overkill of your just changing the width of the sidebar.

Another option is to use what http://www.bennadel.com/blog/680-Defining-A-CSS-Selector-That-Requires-A... calls multi class selectors.

.front.sidebar-left #content{ width:760px; margin-left:436px; margin-right:-1196px; border:solid 1px blue; }

will check for the existing of front and sidebar left, before applying width to the #content div.

You can then have a separate instructions set for the #content div on interior pages with sidebars. .sidebar-left #content { width: 760px; margin-left: 200px; /* The width of #sidebar-left. */ margin-right: -960px; /* Negative value of #content's width + left margin. */ }

not this is different than setting the width of the sidebars themselves, which is easy with either #sidebar-left or .front #sidebar-left.