AH-SID I made a CSS file for my wapsite, but I got some problem. When I visited my wapsite using browser for phone (opera mini and also nokia browser), the background image often not show (blank like not given a style).

Example:

.post { background: url(image.png); }

also I tried
.post { background-image: url(image.png); }

and also I tried to give command !important
.post { background: url(image.png) !important; }

But still not give any effect. What is wrong?