.header-include {
  position: sticky;
  top: 0;
  z-index: 9999;
}

.clean-header {
  background: #ffffff;
  box-shadow:
    0 4px 10px rgba(0,0,0,.12),
    0 18px 35px rgba(0,0,0,.22);
}

.clean-header::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -18px;
  height: 18px;
  z-index: 998;
  pointer-events: none;
  background: linear-gradient(
    to bottom,
    rgba(0,0,0,.30),
    rgba(0,0,0,.12),
    transparent
  );
}