[CSS Hack] border-color: transparent & filter + cleartype bug

IE6 does not support setting the transparent as the border color.

For example:
Border: solid 1px transparent;

Solution:
Border: solid 1px transparent;
/* Set an unused color to be index color */
_ Border-color: Tomato;/* For IE6 -*/
/* Then remove this indexed color */
_ Filter: chroma (color = tomato);/* For IE6 -*/

The result is as follows:

The border is gone. What is the font...
Idea: The above phenomenon is only visible when the cleartype of the system is turned on. If cleartype is turned off, there is no problem. See below:
 
A demo page for this question:
Http://icant.co.uk/sandbox/msieopacityissue/
In addition:
Http://www.hedgerwow.com/360/bugs/fix-ie-opacity-text.html

Solution:
Border: solid 1px transparent;
Background-color: # bfdbff;
/* Set an unused color to be index color */
_ Border-color: Tomato;/* For IE6 -*/
/* Then remove this indexed color */
_ Filter: chroma (color = tomato);/* For IE6 -*/

 
After half a day, the border is transparent, and the background color is not transparent. Sweat !!!