Welcome to the Streamlit community, and thanks for reaching out! 
My understanding is that Streamlit Community Cloud does not natively support connecting a fully custom domain (like yourdomain.com) directly to your app. You can only set a custom subdomain (e.g., myapp.streamlit.app), not your own top-level domain. Attempts to point your domain to Streamlit Cloud via DNS (A or CNAME records) will not work as expected due to SSL and platform limitations. This is confirmed in multiple forum threads and the official docs—see App settings - Streamlit Docs and Custom domain setup fails.
A common workaround is to host a static site (e.g., via GitHub Pages, Netlify, or your Namecheap web hosting) at your custom domain, and embed your Streamlit app in an iframe using the embed=true query parameter (e.g., <iframe src="https://appName.streamlit.app/?embed=true"></iframe>). This masks the Streamlit URL, but note that some features (like navigation) may not work perfectly, and the browser URL will not update with page changes. For more details and community solutions, see Using our own domain instead of subdomain of streamlit and How to link Streamlit to a domain name.
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