no-repeat
is an invalid value for your content
property, so it should be
.image-container img:after {
position: absolute;
margin-top: -50%;
width: 183px;
height: 103px;
content: url(#);
}
Also it won't make sense using display: block;
on absolute
positioned element.
Also, chrome doesn't understand img:after
so better use .image-container:after