Remove the single quotation mark in the URL (see my above comments) and that should display the logo in in all browsers.
Use the below code in custom CSS and follow the instructions in the help for displaying logo in admin page.
#title_text
{
display: none;
}
#title
{
background:url(http://www.domainname.com/studyname/graphics/logopng.png) no-repeat left top;
height: 80px;
padding-right: 2px;
padding-left: 2px;
padding-top: 2px;
padding-bottom: 2px;
}