VERSION 9
Thanks to https://www.odoo.com/forum/help-1/question/how-change-the-logo-size-101691 I managed to change the logo size but now I cannot vertically center the logo.
FROM HTML EDITOR: //Customize/HTML Editor/Show Logo
<?xml version="1.0"?>
<data inherit_id="website.layout" customize_show="True" name="Show Logo">
<xpath expr="//header//a[@class='navbar-brand']" position="replace">
<a href="/" class="navbar-brand logo">
<img src="/logo.png" t-att-alt="'Logo of %s' % res_company.name" t-att-title="res_company.name" style="max-width: 200px; max-height:85px"/>
</a>
</xpath>
</data>
