[twitter-bootstrap] Why do Twitter Bootstrap tables always have 100% width?

Bootstrap 3:

Why fight it? Why not simply control your table width using the bootstrap grid?

<div class="row">
    <div class="col-sm-6">
        <table></table>
    </div>
</div>

This will create a table that is half (6 out of 12) of the width of the containing element.

I sometimes use inline styles as per the other answers, but it is discouraged.

Bootstrap 4:

Bootstrap 4 has some nice helper classes for width like w-25, w-50, w-75, w-100, and w-auto. This will make the table 50% width:

<table class="w-50"></table>

Here's the doc: https://getbootstrap.com/docs/4.0/utilities/sizing/