how to get base url in smarty codeigniter

You made little typo on ";"

{base_url('styles/bootstrap/css/bootstrap-theme.min.css')}

note :

url_helper must be loaded before displaying template

php codeigniter smarty

you can use like this I didn't test this

{'styles/bootstrap/css/bootstrap-theme.min.css'|base_url}

or you can write php code inside template

{php}  $this->assign('my_url',base_url('styles/bootstrap/css/bootstrap-theme.min.css'));{/php}{$my_url}

php codeigniter smarty

I have used this function for my controller in form action to redirect to my method it worked .

{base_url('my_controller/my_method')}