web/web_company_color/view/assets.xml

<?xml version="1.0" encoding="utf-8"?>

<!--
    Copyright 2019 Alexandre Díaz
    License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
-->

<odoo>
    <template id="assets_backend" name="web_company_color assets"
              inherit_id="web.assets_backend">
        <xpath expr=".">
            <t t-set="company_id" t-value="request.env.user and request.env.user.company_id" />
            <link t-if="company_id" rel="stylesheet" type="text/scss"
                  t-att-href="company_id.scss_get_url()" />
        </xpath>
    </template>
</odoo>