basic-button.erb

The button is a little bit out of date, and the html_options are a bit contrived in their usefulness. However, this is how you use it: 

<%= the_button 'Submit', url_options, html_options %>

html_options =  size: specify 'small', if you want the button smaller
                type: specify 'primary' if the button is the primary action on a page
                icon: specify the name of an icon from the icon font
                popup: 'data-popup-value'
                
The submit button is just a simplified version of the_button for submitting forms. 
<%= the_submit_button 'Submit' %>

html_options =  type: defaults to primary,
                outer_class: specify a special class to add to a span wrapping the button itself