The .page-header class has been dropped from version 4. Instead, you should look at using the new display CSS classes on your headers if you want to give them a heading look and feel.

If you've ever used responsive images in the past, the class name has changed. Previously, the class name was .image-responsive but it is now named .image-fluid. You'll need to update that class anywhere it is used.

For the table component, a few class names have changed and there are some new classes you can use.

If you would like to create a responsive table, you can now simply add the class .table-responsive to the <table> tag. Previously, you had to wrap the class around the <table> tag. If migrating, you'll need to update your HTML markup to the new format.

The .table-condensed class has been renamed to .table-sm. You'll need to update that class anywhere it is used.

There are a couple of new table styles you can add called .table-inverse or .table-reflow.

Forms are always a complicated component to code. In Bootstrap 4, some of the class names have changed to be more consistent. Here's a list of the differences you need to know about:

You likely have these classes throughout most of your forms. You'll need to update them anywhere they are used.

There are some minor CSS class name changes that you need to be aware of:

Again, you'll need to update these classes when migrating to the new version of Bootstrap. There are some other minor changes when migrating on components that aren't as commonly used. I'm confident my explanation will cover the majority of use cases when using Bootstrap 4. However, if you would like to see the full list of changes, please visit:

http://v4-alpha.getbootstrap.com/migration/ .