Sometimes you may want to include a background in your separator or make the borders invisible . I use this often when using applicability rules to hide attributes as opposed to READ PROTECT - I place the attributes inside a separator and then make the separator invisible, but still there - it's much faster and more efficient - also run the applicability rule as dynamic on the form using a yes/no attribute based rule on the object
If you wish to do this , place the following code in the render script section of the advanced button on the form and then add the custom settings to your custom MyClass css file
Advanced Button (Render Script section):
var field = parser.getField ("Address1");
var id = field.getId ();
var separator = $("#" + id).closest ("fieldset");
separator.addClass ("MyClass");
(The above var field needs to know at least one attribute name placed inside the separator to be customised, I am using "Address1" in this example))