Boostrap 3.4 - Arrange multiple buttons in two columns - html

Question

I am trying to arrange a few buttons in boostrap 3.4.
I managed to do it (probably by luck) and this is how it looks
This is the code I used. The idea is to create rows and then various divs within the row with the appropriate columns widths col-xs-N.
<div id="cfd_panel" class="panel panel-primary">
<div class="panel-heading">
<div class="panel-title">
<a data-toggle="collapse" data-parent="#analysis" href="#collapse2">CFD</a>
</div>
</div>
<div id="collapse2" class="panel-collapse collapse">
<div class="row">
<div class="col-xs-6">
<button type="button" class="btn btn-block btn-default btn-sm" id='create_cfd_domain' onclick='create_cfd_domain_btn()'>
Create/Update Domain
</button>
</div>
<div class="col-xs-3" style="padding-right: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" onclick='map_to_area_btn()' >
Airflow Map
</button>
</div>
<div class="col-xs-3" style="padding-left: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" onclick='open_cfd_paraview_btn()' >
View
</button>
</div>
</div>
<div class="row">
<div class="col-xs-6">
<button type="button" class="btn btn-block btn-default btn-sm" id='mesh_cfd_domain' onclick='openfoam_mesh_btn()'>
Mesh
</button>
</div>
<div class="col-xs-3" style="padding-right: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" onclick='open_cfd_paraview_samples_btn()' >
Samples
</button>
</div>
<div class="col-xs-3" style="padding-left: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" onclick='import_from_aws_btn()' >
Import
</button>
</div>
</div>
<div class="row">
<div class="col-xs-3" style="padding-right: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" id='run_cfd_cases' onclick='openfoam_run_btn()'>
Run
</button>
</div>
<div class="col-xs-3" style="padding-left: 1px">
<button type="button" class="btn btn-block btn-default btn-sm" id='sample_cfd_cases' onclick='openfoam_get_results_btn()' >
Sample
</button>
</div>
<div class="col-xs-6" style="padding-left: 10px; ali">
<button type="button" class="btn btn-link btn-sm" id='open_cfd_settings' onclick='open_cfd_settings_btn()' >
Settings
</button>
<button type="button" class="btn btn-link btn-sm" id='open_wind_template' onclick='open_wind_template_btn()' >
OFTemplate
</button>
</div>
</div>
</div>
</div>
I am now trying to rearrange the buttons in a different way, but I cannot manage to do it correctly by changing the column widths. This is what happens. The goal is to have MESH and RUN button on the same line and on the first column.
Is there a proper way to do it?