DRUPAL7 Formapi to add CSS styles to elements

For example, I define a FORM element called the Package library start date,

$form [' Starttime_baoyue ']=array(    ' #type ' = ' TextField ',    ' #title ' =>t (' package libraries start date '),    TRUE,  );

As shown in the code, there are no styles, except for some CSS styles that Drupal adds by default, such as:

So, the actual work, the front-end to a style sheet, there is a fixed style, then how to add to this element?

It's really simple: just add a line of code:

' #attributes ' = =Array(' class ' = =array(' My_class_name ')),

The complete code for the entire element becomes

$form [' Starttime_baoyue ']=array(    ' #type ' = ' TextField ',    ' #title ' =>t (' package libraries start date '),    TRUE,    ' #attributes ' = =Array(' class ' = =array(' My_class ')),   );

Refresh the page and look at the final HTML of the element:

How, the style ' My_class ', has been added bar ~

DRUPAL7 Formapi to add CSS styles to elements