Hi Jonathankabre1, 

<div style="opacity:0.15; font-size:100px; text-align:center; position:fixed; top:600px; right:100px; z-index:99; transform:rotate(-30deg);">

    <img t-if="doc.company_id.logo"

         t-att-src="image_data_uri(doc.company_id.logo)"

         style="max-width:80%; max-height:140pt; min-width:80%; min-height:50pt;"

         alt="Logo"/>

</div>

Try this 


Hope this helps.