/* base block (works if the class is on the heading itself or on its wrapper) */
.vc_custom_heading.h2-box,
.h2-box .vc_custom_heading,
.h2-box h1, .h2-box h2, .h2-box h3{
  position: relative;
  display: block;
  margin: 28px 0 18px;
  padding-bottom: 14px;   /* room for the line */
  line-height: 1.2;
  overflow: visible;
}

/* center/left alignment helpers */
.h2-box.center{ text-align: center; }
.h2-box.left{ text-align: left; }

/* the blue underline */
.vc_custom_heading.h2-box:after,
.h2-box .vc_custom_heading:after,
.h2-box h1:after, .h2-box h2:after, .h2-box h3:after{
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: #00aeef;   /* your blue */
  border-radius: 2px;
}

/* left-aligned underline variant */
.h2-box.left .vc_custom_heading:after,
.h2-box.left h1:after, .h2-box.left h2:after, .h2-box.left h3:after{
  left: 0;
  transform: none;
}