themes-wordpress/blockbase/sass/base/_alignment.scss

.wp-block-group.alignfull,
*[class*="wp-container-"] //Anything that inherits layout (container)
{
	//give it some padding
	padding-left: var(--wp--custom--post-content--padding--left);
	padding-right: var(--wp--custom--post-content--padding--right);

	//Any nested containers, and anything that is alignfull
	*[class*="wp-container-"], // Any nested containers
	> .alignfull { // Any direct descendant that is alignfull
		// bust out of the container's padding
		margin-left: calc(-1 * var(--wp--custom--post-content--padding--left)) !important;
		margin-right: calc(-1 * var(--wp--custom--post-content--padding--right)) !important;
		width: calc( 100% + var(--wp--custom--post-content--padding--left) + var(--wp--custom--post-content--padding--right) ) !important;
	}
}

@include break-mobile {
	// limit size of any element that is aligned left/right
	.wp-block[data-align="left"], // This is for the editor
	.wp-block[data-align="right"], // This is for the editor
	.wp-site-blocks .alignleft,
	.wp-site-blocks .alignright {
		max-width: var(--wp--custom--alignment--aligned-max-width);
	}
}

// This was added for the 'site-logo' block which centers with an 'align:center' attribute
// instead of 'textAlign' center which sets an .aligncenter class instead of a has-text-align-center
// class which would do this for us.  I'm not sure why but this centers things appropriately.
.aligncenter {
	text-align: center;
}