eiru_internet_check/templates.xml

<openerp>
    <data>
        <template id="eiru_internet_check_assets" inherit_id="web.assets_eiru">
            <xpath expr="." position="inside">
                <!-- Dependency -->
                <script type="text/javascript" src="/eiru_internet_check/static/lib/offline.js" />

                <!-- Main assets -->
                <link rel="stylesheet" href="/eiru_internet_check/static/src/css/main.css" />
                <script type="text/javascript" src="/eiru_internet_check/static/src/js/main.js" />
            </xpath>
        </template>

    </data>
</openerp>