Apply css styling to module,

module specific css.

• Step1: create below folder(s) inside require module(crm_helpdesk)

crm_helpdesk/static/src/css

• Step2: inside css folder create your css file. like style.css

• Step3: inside style.css file do whatever customization require for css, its module specific.

• Step4: then inside __openerp__.py add reference of css file.

{
    'name': 'Helpdesk',
    'category': 'Customer Relationship Management', 
    'version': '1.0',
    ......,
    'css': ['static/src/css/style.css'],

}

Note:

Whatever class you create inside css for styling, please apply to field in view file too.