how to add conditional styles? How can I insert the following:

&lt;!--[if lte IE 9]&gt;
    &lt;style type='text/css'&gt;
  #page{display: none;}
    &lt;/style&gt;
&lt;![endif]--&gt;


I tried it in page.tpl.php but not worked.
Put it in html.tpl.php also it work in page.tpl.php but I think you did not clear cache , please dont forget this, clear cache after templates changes.

also you can use conditional css 
this link help you 

https://drupal.org/project/conditional_styles