Problems with layout on bootstrap. How to fix?

Question

css

Good afternoon!
Somehow the layout behaves very strange when the screen changes - adaptability (for mobile devices)
layout here
Please tell me what's wrong? Why are the pictures misbehaving?
Thank you in advance for your help.

Answer 1

showcase-item {
height: 599px;
and if you consider that you also didn’t correctly insert the link " https://toster.ru/www.yourbitw.com ", maybe you shouldn't learn bootstrap yet? Before shooting from a machine gun, can a gun be mastered?