custom line

Custome line code that I made:

.av-masonry-sort.main_color:after {
 background-color: #005471;
 content: "";
 display: inline-block;
 height: 1px;
 vertical-align: middle;
 width: 100%;
}

.av-masonry-sort.main_color:after {
  margin-top: -6%;
	margin-left: 65%;
}

Line is not responsive if screen size is smaller or selection of filter becomes bigger..
How can I fix this?

Thanks in advance!