Колонки могут быть созданы с отступом от края экрана слева. Пример кода:

<div class="row">
  <div class="col col-33 col-offset-33">.col</div>
  <div class="col">.col</div>
</div>

<div class="row">
  <div class="col col-33">.col</div>
  <div class="col col-33 col-offset-33">.col</div>
</div>

<div class="row">
  <div class="col col-33 col-offset-67">.col</div>
</div>

Note: The borders and gray background in the demo were added so it's easier to see the structure.

Offset Column Percentage Classnames
.col-offset-10 10%
.col-offset-20 20%
.col-offset-25 25%
.col-offset-33 33.3333%
.col-offset-50 50%
.col-offset-67 66.6666%
.col-offset-75 75%
.col-offset-80 80%
.col-offset-90 90%