How to set theme style based on subdomain in multi-vendor setup?

My company has multiple brands selling from the same website because they are all subsidiaries of the main company. We have each company setup as subdomains with various {% case request.host %} to check which subdomain the customer is currently shopping on to change the shopping experience. That being said, I need a little help setting the current theme style based on the subdomain.

For example, right now I have the below to change the header to custom duplicated headers (with changes):

{% case request.host %}
  {% when 'viphomeandgarden.transpacbrands.com' %}
    {% section 'header-viphomeandgarden' %}
  {% when 'totaleegift.transpacbrands.com' %}
    {% section 'header-totaleegift' %}
  {% when 'seasonsdesigns.transpacbrands.com' %}
    {% section 'header-seasonsdesigns' %}
  {% else %}
    {% section 'header' %}
  {% endcase %}

In settings_data.json I have changed the preset styles to reflect the branding of each company (font, color, etc.) but now I need code similar to the above to set the style based on the current subdomain a customer is shopping in. I’ve seen other posts about changing single sections using !important but because this affects so many things it’d be much easier to utilize the theme styles. All the subdomains/companies are on the same Shopify Theme so that’s not an issue.