If it's accessible to you, another choice could be utilizing a CSS3 gradient as the backdrop instead:
background-image: linear-gradient(left , rgb(0,0,0) 0%, rgb(0,0,0) 50%, rgb(12,97,35) 50%);
background-image: -o-linear-gradient(left , rgb(0,0,0) 0%, rgb(0,0,0) 50%, rgb(12,97,35) 50%);
background-image: -moz-linear-gradient(left , rgb(0,0,0) 0%, rgb(0,0,0) 50%, rgb(12,97,35) 50%);
background-image: -webkit-linear-gradient(left , rgb(0,0,0) 0%, rgb(0,0,0) 50%, rgb(12,97,35) 50%);
background-image: -ms-linear-gradient(left , rgb(0,0,0) 0%, rgb(0,0,0) 50%, rgb(12,97,35) 50%);