Help needed forTribute page making it responsive

[dlshort]

Hi, I have some questions about bootstrap grid system.
If I use .col-lg-12, what is the short code for medium, small and extra small?
Trying to set it up throw the docs but every time I fail. Please help.
Codepen link

[rickstewart]

Give this a try, it describes the grid system pretty well. BootStrap Grid System

[dlshort]

Finally I figured it out
Thanks for help.