css class name inside a bootstrap class code example
Example 1: bootstrap 3 offset
col-sm-offset-2
Example 2: bootstrap container width
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Bootstrap Container Width | Size | Class Prefix
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Extra small devices Phones (less than 768px) | None (auto) | .col-xs-
Small devices Tablets (greater than equals 768px) | 750px | .col-sm-
Medium devices Desktops (greater than equals 992px) | 970px | .col-md-
Large devices Desktops (greater than equals 1200px) | 1170px | .col-lg-