Get a Local Copy of Bootstrap
If you can't access Bootstrap from the CDN, you'll need to pull it in via NuGet or your preferred package manager (npm, bower, etc.). This will download the files into your solution so that they don't require any external connections.
Additionally, you can download Bootstrap directly if you would prefer that approach.
Reference the Local File
Once you have it in your solution, you'll just need to reference it by location within the
<head> section of your
<!-- Point to the location within your solution that Bootstrap is stored --> <link href="~/Content/bootstrap.min.css" rel="stylesheet" type="text/css" />
Or you can simply drag-drop it from your Solution Explorer :
If you are still encountering issues, consider checking the Developer Tools (F12) within your browser and clearing your cache to ensure the latest files are being pulled properly.