.subnav--page-layout {
  position: unset;
  height: 100%;
  margin-top: 20px;
  background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#f5f5f5), color-stop(100%,#F5F5F5));
  border-width: 10px;
  border-style: solid;
  border-color: #F2DEDE;
  border-radius: 4px;
}

ul.nav.nav-pills.rows {
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
}

.subnav--page-layout {
  position: unset;
  height: 100%;
  margin-top: 20px;
  background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#f5f5f5), color-stop(100%,#F5F5F5));
  border-width: 10px;
  border-style: solid;
  border-color: #F2DEDE;
  border-radius: 4px;
}

ul.nav.nav-pills.rows {
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -webkit-flex-direction: column;
      -ms-flex-direction: column;
          flex-direction: column;
  -webkit-flex-wrap: wrap;
      -ms-flex-wrap: wrap;
          flex-wrap: wrap;
}

Add vender prefix for CSS
Add vender prefix for CSS
