Hard because bootstrap is usefull for responsive, non static...
Can it be correct with this way : http://bootply.com/98214
html
<div class="row">
<div id="col1" class="col-xs-6 col-md-5">coco 1</div>
<div id="col2" class="col-xs-6 col-md-2">coco 2</div>
</div>
css
#col1{
background:green;
max-width:800px !important;
}
#col2{
background:yellow;
max-width:400px !important;
}
You shouldn't use min-width because in case of extra small device, it won't have a good render