Answers for "adding left margin to the container in boostrap container"

bootstrap Margin and padding

Use the margin and padding spacing utilities to control how elements and 
components are spaced and sized. Bootstrap 4 includes a five-level scale for
spacing utilities, based on a 1rem value default $spacer variable. Choose
values for all viewports (e.g., .mr-3 for margin-right: 1rem), or pick
responsive variants to target specific viewports (e.g., .mr-md-3 for 
margin-right: 1rem starting at the md breakpoint).

<div class="my-0 bg-warning">Margin Y 0</div>
  <div class="my-1 bg-warning">Margin Y 1</div>
  <div class="my-2 bg-warning">Margin Y 2</div>
  <div class="my-3 bg-warning">Margin Y 3</div>
  <div class="my-4 bg-warning">Margin Y 4</div>
  <div class="my-5 bg-warning">Margin Y 5</div>
  <div class="my-auto bg-warning">Margin Y Auto</div>

bootstrap, apply margin only on small screen

<div class="mobile-margin visible-xs"></div>