web/web_clean_navbar/views/clean_navbar.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>
<template id="clean_navbar" name="Clean Navbar" inherit_id="web.assets_backend" active="True">
	<xpath expr="//link[@href='/web/static/src/css/base.css']" position='after'>
            <link rel="stylesheet" href="/web_clean_navbar/static/src/css/clean_navbar.css"/>
    </xpath>
</template>
</data>
</openerp>