Change color of label

Hi

I'm trying to change the color of the labels on mandatory fields in the edit/detail views.

I created a custom.less css file with the following

.redlabel {
    color: black;
    background-color : yellow;    
}
label {
  color: red;
}

When I add the css class to the field in the record.php the background color and text of the field changes but not the label, is this affected somewhere else?

record.php

array (
        'css_class' => 'redlabel',
                'name' => 'gig_date_from_c',
                'label' => 'LBL_GIG_DATE_FROM',
              ),