CSS editor

I recently changed the width of a widget to 150px from 300px with success. When i tried to revert it by typing in 300px again, the change didnt happen. The widget width remained at 150px. I saved a backup before all this in a textdocument and copied it back to the Editor under appearance with no result. I actually tried to remove all text and still nothing happens, it feels like the homepage does not respond to CSS changes. Any ideas?

I changed the width to 150px and then back to 300px, but it remains 150px
/**************** Sidebar *******************************/

#secondary {
float:left;
width:300px;
}

Thanks