design-themes/theme_yes/views/snippets/s_images_wall.xml

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

<template id="s_images_wall" inherit_id="website.s_images_wall">
    <!-- Images -->
    <xpath expr="//img" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
    <xpath expr="(//img)[2]" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
    <xpath expr="(//img)[3]" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
    <xpath expr="(//img)[4]" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
    <xpath expr="(//img)[5]" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
    <xpath expr="(//img)[6]" position="attributes">
        <attribute name="class" add="rounded" separator=" "/>
    </xpath>
</template>

<template id="configurator_s_images_wall" inherit_id="website.configurator_s_images_wall">
    <!-- Shape option -->
    <xpath expr="//section" position="attributes">
        <attribute name="data-oe-shape-data">{"shape":"web_editor/Floats/12"}</attribute>
    </xpath>
    <!-- Shape -->
    <xpath expr="//*[hasclass('container')]" position="before">
        <div class="o_we_shape o_web_editor_Floats_12"/>
    </xpath>
</template>

</odoo>