Hi, i am using odoo11.

I wanted to experiment with custom reports for accounting. So I added a special "print invoice griglia" in the print menubar by means of the following code:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>        
        <report
            id="custom_invoice_griglia"
            model="account.invoice"
            string="Invoices griglia"
            report_type="qweb-pdf"
            name="custom_invoice.report_invoice_griglia"
            file="custom_invoice.report_invoice_griglia"
            attachment="(object.state in ('open','paid')) and ('INV'+(object.number or '').replace('/','')+'.pdf')"
            print_report_name="(object._get_printed_report_name())"
        />

         <template id="report_invoice_griglia">
            <t t-call="web.html_container">
                <t t-foreach="docs" t-as="o">
                    <t t-call="custom_invoice.report_invoice_griglia" t-lang="o.partner_id.lang"/>
                </t>
            </t>
        </template>

        <template id="report_invoice_griglia">
            <t t-if="not o and doc">
                <t t-set="o" t-value="doc"/>
            </t>
            <t t-if="o and 'company_id' in o">
                <t t-set="company" t-value="o.company_id.sudo()"/>
            </t>
            <t t-if="not o or not 'company_id' in o">
                <t t-set="company" t-value="res_company"/>
            </t>
            <t t-call="web.html_container">
                <div class="article" style="margin-top:0px;padding-top:0px;">
                    Hello there
                </div>
            </t>
        </template>
    </data>
</odoo>

And it sorta works: i effectively end up with a blank pdf file containing the "Hello there" string. The only problem is that there's a lot of blank space on top of the page, before the "hello there".

I tried to fix it by merely setting margin and padding of the 'page' tag to zero, but this does not appear to have any affect. I also noticed that if you remove the class="article" attribute, no page is generated and an empty pdf is outputted instead. 

So i tried to find some css rule for "article" by grepping:

grep -rl "\.article" *

but no result is found.

So where does the space at the top of a blank report come from? Is there a way to get rid of it? Thank you very much in advance for any help!