It does not work for me. 

Here is my exemple :

I would like to put the 3 fields on the same line. 

My xml is (with 3 syntaxes for the width clause : with %%, px, and nothing) :

    <field name="partner_id" position="after">
        <label for="contact_name"/>
        <div>
            <field name="title" placeholder="Genre/Titre" class="oe_inline" options="{&quot;no_open&quot;: True}" width="12"/>
            <field name="contact_firstname_id" string="Prénom" placeholder="Prénom par complétion"
                options="{'create_name_field': 'contact_firstname'}"
                class="oe_edit_only oe_inline" on_change="1" width="20%%"/>
            <field name="contact_lastname" placeholder="Nom" class="oe_inline" width="100px"/>
        </div>
    </field>

I tried also the syntax `style="width:...."` and nothing changes 

can you help me ?