I took a different route then you since you to my reasoning you have to look at all elements as text and hence display them inline.
.div {
width:960px;
text-align:center;
}
.divider {
font-size: 16px;
font-weight: 400;
background-color: #fff;
padding-right: 10px;
display: inline-block;
width:10%;
padding: 0 3px;
vertical-align: middle;
}
.div-line {
border-bottom: 1px solid #f0f0f0;
border-top: 1px solid #f0f0f0;
width: 40%;
height: 1px;
display: inline-block;
vertical-align: middle;
}
Here's a fiddle