<h1 class="cp_h1title">見出しテキスト</h1>
.cp_h1title{
border-bottom: solid 4px #4DD0E1;
position: relative;
padding: .3em 0;
}
.cp_h1title:after {
position: absolute;
content: " ";
display: block;
border-bottom: solid 4px #006064;
bottom: -4px;
width: 15%;
}