Here is a quick example:

As you can see in the image above, all the labels, tables are aligned to the margin inside th container(green margin) but the select seems to go over it, i see on css it has 15 padding, but the padding is only for the text inside.
<%--MODULES--%>
        <div class="col-md-6 col-sm-12" id="prueba">
            <div class="row">
                <label class="col-xs-12">Módulos</label>
                <select class="col-xs-12" multiple="multiple" id="cboModulos" name="cboModulos">
                </select>
            </div>
        </div>
Same thing happens with the textbox in the right, but i bet its the same case.
Thanks
                        
You need to add a
.containerdiv around your content. The.rowclass has negative margins to offset column padding which is causing your elements to be misaligned.When using a grid system, the grid classes should be applied to block level elements only (inputs are inline, not block). I have refactored your code with grid wrappers around the elements.
Updated Fiddle