/* v2: the header stays. Clear over the campfire; past it, a solid bar of the ground colour; it tucks away while you
   scroll down and comes back the moment you scroll up. */
.top{position:fixed;transition:background .5s var(--ease),color .5s var(--ease),transform .6s var(--ease),box-shadow .5s var(--ease),padding .5s var(--ease)}
.top.solid{background:rgba(233,225,218,.94);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);color:var(--ink);
  box-shadow:0 1px 0 rgba(18,18,18,.1);padding-top:calc(var(--pad) * .45);padding-bottom:calc(var(--pad) * .45)}
.top.tuck{transform:translateY(-110%)}
.top.solid .mark{--duck-x:transparent}