design-themes/theme_loftspace/views/snippets/s_comparisons.xml

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

<template id="s_comparisons" inherit_id="website.s_comparisons">
    <!-- Card #1 -->
    <xpath expr="//div[hasclass('card')]" position="attributes">
        <attribute name="class" add="bg-o-color-3" separator=" "/>
    </xpath>
    <!-- Card #3 -->
    <xpath expr="(//div[hasclass('card')])[3]" position="attributes">
        <attribute name="class" add="bg-o-color-3" separator=" "/>
    </xpath>
</template>

</odoo>