Boostrap 3 and 4

Hi everyone
I have a trouble when coding on
When i add bootstrap 4, the result was so different.
My buttons were not located in the same row
Anyone can tell me the reason pls
Thanks a lot for reading <3

There are different versions of bootstrap. When any software changes the first number of a version it is a major revision meaning things are much different from (in this case) 3 to 4.
Minor version changes Eg 3.1 to 3.3 means things are less likely to break.

Can you please post the link to your Codepen?