Hi,
You can create your custom css file under:
your_module >> static >> src >> css >>my_css.css
You can then define your class in the my_css.css file. For eg:
.openerp .your_custom_button {
font-weight: normal;
width: 132px !important;
height: 40px;
color: #666;
margin: 0px -1px -1px 0px;
padding: 0;
border: 1px solid #dddddd;
border-radius: 0;
box-shadow: none;
background: white;
}
To include your css file, add the following in templates.xml file.
<template id="assets_backend" name="test_module assets" inherit_id="web.assets_backend">
<xpath expr="." position="inside">
<link rel="stylesheet" href="/test_module/static/src/css/my_css.css"/>
</xpath>
</template>
Then you can use class ="your_custom_class" attribute in your button definition in xml file.