Custom theme CSS not working

I copied over the theme directory from Sunshine into my Custom theme directory as instructed by the Sunshine Docs and named it “sunshine”. I can alter all the template files just fine and they will change the look of my gallery. But when I alter the CSS file in that same directory nothing changes. When using chrome inspection tool I see that my custom CSS is not even being loaded. This plugin is still using the CSS file from the main theme in the sunshine plugin directory not my custom theme folder. This is not good cause when I update the plugin the CSS will be overwritten. Why is it not grabbing the CSS file from the custom sunshine theme folder but it grabs the template files from that folder just fine.

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