Make index.php main-body content "container-fluid" only?

[melds]

i have some content for my home page that I wish to have full width (container fluid)

 

This appears to be controlled in the main body(section id) which has the class of container.

 

How can I change this to be container-fluid for the index.php only, but not affect all the other template pages that use the main-body section.

 

There is nothing in the header.tpl file that refers to this main body content.

[sentq]

here is how to apply it to homepage

class="{if $templatefile=='homepage'}container-fluid{else}container{/if}"