Bootstrap 3행에서 12개 이상의 열을 사용하는 방법은 무엇입니까?

<code class="css">/* col-xs float fix for large column groups */
.large-group .col-xs-12 {
    float: left;    
}

/* col-sm float fix for large column groups */    
@media (min-width: 768px) {    
    .large-group .col-sm-12 {    
        float: left;    
    }    
}

/* col-md float fix for large column groups */    
@media (min-width: 992px) {    
    .large-group .col-md-12 {    
        float: left;    
    }    
}

/* col-lg float fix for large column groups */    
@media (min-width: 1200px) {
    .large-group .col-lg-12 {    
        float: left;    
    }    
}</code>

<code class="html"><div class="container">
    <div class="row large-group" style="background-color:#ebebeb;">    
        <div class="col-xs-9"><div style="background-color:#babeee;"><p>col 9</p></div></div>    
        <div class="col-xs-3"><div style="background-color:#fefeeb;"><p>col 3</p></div></div>    
        <div class="col-xs-12"><div style="background-color:#bada55;"><p>col 12</p></div></div>    
    </div>    
</div></code>