Issues with larger logo in IE

Hi I have added a larger logo to the header and changed style.css in the child theme by adding this code:

/*default header: main logo and main menu height. increase max value if you want to use a bigger logo*/
#header_main .container, .main_menu ul:first-child > li a{ height:150px; line-height: 88px; }
.fixed_header #main{ padding-top:150px; } /* padding of the main container should be equal height as the header height above*/

This works fine in most browsers but the logo does not resize in IE8 when you scrawl down. The menu resizes as it should but the logo stays the same size which makes it being cut off.

How can I fix this issue because more then half of the current site visitors are using IE8.

Thank you,