Hey @yidanwang I believe that you can access that using the {{ name }} variable in HubL within the custom module. Here is an example where I used the variable in my code:
And the output that I received in the HTML as a result:
So in your case you might need something like:
.hs_cos_wrapper_{{name}} {
}
Please note that HubL can only be used in the HTML pane of the custom module editor so you might need to put your CSS in some <style> tags in the HTML pane and wrap that in {% require_css %}{% end_require_css %}