background-size not working properly in chrome

background-size not working properly in chrome

i have a left admin panel which is set in percentage width. the problem is
that i have a repeating background in it and when i use background-size to
tuck-in the background image to the size of percentage-based width, the
image just disappears in chrome. in firefox it works fine. But when i use
ctrl - to zoom-out the display, the image appears. the css of the left
panel is:
.adminmenuback {
width: 30%;
background: url(../images/leftpanel_bg.png) left top repeat-y;
background-size: 100%;
color: #fff;
position: absolute;
top: 0;
bottom: 0;
height: 100%;
}
pls help.