make all titles even

Hi everyone,

on my website http://www.ziamojewels.com/shop, there is a sidebar and I finally succeeded to add lines to my widget title with this code:

.widget h4 {
  margin-top: 10px;
  margin-bottom: 5px;
  line-height: 0.5;
  text-align: center;
  color: #a1a1a1;
  font-weight: normal;
  padding-bottom: 10px;
  padding-top: 12px;
  font-size: 17px;
}
.widget h4 span {
  display: inline-block;
  position: relative;
}
.widget h4 span:before,
.widget h4 span:after {
  content: "";
  position: absolute;
  height: 5px;
  border-bottom: 1px solid #a1a1a1;
  top: 20px;
  width: 50px;
}
.widget h4 span:before {
  right: 100%;
  margin-right: 20px;
}
.widget h4 span:after {
  left: 100%;
  margin-left: 20px;
}

But as you can see, the lines/titles aren’t even (shop by material is ‘longer’ than ‘sort by’. How can I make this look cleaner? any ideas?

Thank you so much!