If you have a theme applied to your Site Collection and want to provide different theme/experience on one of your subsites, then this article is for you.

Before we Start ( ShortPoint Add-In )

If you are using ShortPoint On-Premise 2013 or ShortPoint On-Premise 2016, you can skip to the next section.

Part 1: ShortPoint installed on entire Site Collection

If you are using ShortPoint Add-In, this article assumes that you already have ShortPoint installed on your entire site collection, 

To verify this, 

1. go to the root of your site collection > Site Settings > ShortPoint Dashboard,

2. and you should see "Installed on entire Site Collection" next to the ShortPoint version in your Dashboard ( see next figure ):

Part 2: Add & Install ShortPoint on the Subsite

Go to the subsite that you wish to have different Theme applied on, and do the following:

1. From the Office 365 cog menu, click on Add an app ( as shown in the next image ), and Choose ShortPoint:

2. Once ShortPoint is added to your subsite, click on it ( which will open the ShortPoint Dashboard ), Go to the Install tile, and install ShortPoint

Before we Start ( ShortPoint On-Premise 2013/On-Premise 2016 )

We assume that you have installed ShortPoint without touching any ShortPoint feature on either Site collection level or on the subsite level.

So If you go to your root site > Site Settings > Site collection features, you should see ShortPoint feature active.

And if you go to the subsite that you wish to have a different theme on > Site Settings > Manage site features, you should see ShortPoint feature inactive.

Step 1: Go to ShortPoint Site Customization on the Subsite

On your subsite, go to Site Settings > ShortPoint Dashboard > and click on the Site Customization Tile:

Step 2: Stop the Inheritance

You will see in the Site Customization page, a warning message telling you that the site is inheriting from the parent site, we need to click on the Stop inherit settings, in order to for the Customize my site button gets enabled on this subsite.

Step 3: Start customizing your Subsite!

Now you will see that Customize my site button is active, which mean the applied theme on the parent site is no longer applied here on the subsute, and that you can start customizing and applying a different theme to your subsite.