I'm following an online tutorial, just started a simple MVC website project in VS2017 Community Edition. The view is using the default auto-generated _layout.cshtml, its referencing Bootstrap v3.3.7.
I tried to update the Bootstrap.css by replacing it with this one: (v4.1.1) https://bootswatch.com/4/yeti/bootstrap.css, however, instead of looking like this: !https://i.stack.imgur.com/0IeK9.jpg
it appeared as this: !https://i.stack.imgur.com/o9bIe.jpgenter image description here
The whole menu bar remain collapsed after upgrading from v3.3.7 to v4.1.1
Wonder what I did wrong, or how can I make it right.
Any advice is appreciated!