Center individual pages within full width

Here is the css I used to make the site full width.
.wrap {
/* margin-left: auto; */
/* margin-right: auto; */
max-width: 100%;
/* padding-left: 2em; */
/* padding-right: 2em; */
}

@media screen and (min-width: 48em) {
.wrap {
max-width: 100%;
/* padding-left: 3em; */
/* padding-right: 3em; */
}
}

.page.page-one-column:not(.twentyseventeen-front-page) #primary {
/*margin-left: auto;*/
/*margin-right: auto;*/
max-width: 100%;
}

@media screen and (min-width: 30em) {
.page-one-column .panel-content .wrap
{
max-width: 100%;
}
}

Do those pages you want centred have anything in common, like a gallery that you always want centred?

Ah, yes, they are all the pages with galleries on. Primary Art, Secondary Art and the Creatives pages. I use Tiled Gallery Carousel Without JetPack.

In the “Edit JS Code” section of the dashboard (available via https://www.ads-software.com/plugins/custom-css-js/) , try adding this:

var $ = jQuery,
    gallery = $('.tiled-gallery'),
    bodyClass = 'js-page-template-gallery';

if (gallery.length !== 0) {
    $('body').addClass(bodyClass);
}

Remember to set an option of “Footer” underneath the setting “Where on page”: https://ps.w.org/custom-css-js/assets/screenshot-3.jpg?rev=1770918

Then in your Child Theme style.css file/ Additional CSS section of the dashboard add this:

.js-page-template-gallery .site-main {
    max-width: 735px;
    margin: 0 auto;
}

Perfect, this works, I am very grateful for your help ??