help with preg_replace pattern

[Rob Gould <gouldimg@xxxxxxx>]

It appears that IE renders it's display: none in all caps while Firefox and other browsers pass it back in lowercase.  This throws off my php line of code the is supposed to nuke blank bullets from a string of text:
$bl = 
<LI style="DISPLAY: none" id=bullet_ug2_col5_8></LI> 
<LI style="DISPLAY: none" id=bullet_ug2_col4_8></LI> 
<LI style="DISPLAY: none" id=bullet_ug2_col3_8></LI> 
<LI style="DISPLAY: none" id=bullet_ug2_col2_8></LI> 
<LI style="DISPLAY: none" id=bullet_ug2_8></LI> 
<LI style="DISPLAY: none" id=bullet_ug1_col4_8></LI> 
<LI style="DISPLAY: list-item" id=bullet_ug1_col3_8>Reserved Frontstretch Tower Ticket to the NextEra Energy Resources 250 on Friday Night </LI> 
<LI style="DISPLAY: list-item" id=bullet_ug1_col2_8>Reserved Frontstretch Tower Ticket to the Camping World 300 on Saturday </LI> 
<LI style="DISPLAY: list-item" id=bullet_2_8>Reserved Frontstretch Tower Ticket to the Daytona 500 on Sunday </LI> 
<LI style="DISPLAY: none" id=bullet_addon_col2_8></LI> 
<LI style="DISPLAY: none" id=bullet_addon3_8></LI> 
<LI style="DISPLAY: none" id=bullet_option2_col4_8></LI> 
<LI style="DISPLAY: none" id=bullet_option2_col3_8></LI> 
<LI style="DISPLAY: none" id=bullet_option2_col2_8></LI> 
<LI style="DISPLAY: none" id=bullet_option2_col1_8></LI> 
<LI style="DISPLAY: none" id=bullet_option3_col4_8></LI> 
<LI style="DISPLAY: none" id=bullet_option3_col3_8></LI> 
<LI style="DISPLAY: none" id=bullet_option3_col2_8></LI> 
<LI style="DISPLAY: none" id=bullet_option3_col1_8></LI> 
<LI style="DISPLAY: none" id=bullet_option4_col4_8></LI> 
<LI style="DISPLAY: none" id=bullet_option4_col3_8></LI>

I want to keep the "DISPLAY: list-item" lines, and nuke all the others.
The below above are sent to PHP in a variable called $bl.  I then try to nuke the "DISPLAY: none" lines with something like:

$pattern = '/<li[^>]*style="display: none[^>]*>/';
$bl = preg_replace($pattern,'',$bl);

$pattern = '/<li[^>]*style="DISPLAY: none[^>]*>/';
$bl = preg_replace($pattern,'',$bl);

But it appears that the case-sensitivity fix is not just a matter of making the letter capitals.  I'm sure someone who knows more than I about preg_replace will see the 
immediate error of my ways.  Any advice is greatly appreciated.