Can you explain what 'md' stands for in this context? I understand that 'm' refers to margin, but what about 'd' in the first line of code?
Also, what does the 'n' in 'n2' stand for? How is it different from simply using the number '2' like in the second line of code?
<a class="navbar-brand mr-md-n2">
<a class="navbar-brand mr-md-2">