/* 共用外殼：只有一條頂欄。刻意極薄——三條軌跡各有自己的視覺語言，
   外殼不該蓋過它們，只負責讓人知道「這裡還有別的」。 */
.lab-shell{position:sticky;top:0;z-index:9999;display:flex;align-items:center;gap:.75rem;
  padding:.5rem max(1rem,env(safe-area-inset-left)) .5rem max(1rem,env(safe-area-inset-left));
  font:500 13px/1.4 system-ui,-apple-system,"Noto Sans TC",sans-serif;
  background:rgba(12,12,14,.92);color:#e8e8ea;backdrop-filter:blur(8px);
  border-bottom:1px solid rgba(255,255,255,.12)}
.lab-shell a{color:#e8e8ea;text-decoration:none;opacity:.75}
.lab-shell a:hover{opacity:1;text-decoration:underline}
.lab-shell .sep{opacity:.35}
.lab-shell .here{opacity:1;font-weight:600}
@media print{.lab-shell{display:none}}
.lab-shell .cta{margin-left:auto;opacity:1;font-weight:600;padding:.2em .7em;
 border:1px solid rgba(255,255,255,.28);border-radius:6px;white-space:nowrap}
.lab-shell .cta:hover{background:rgba(255,255,255,.12);text-decoration:none}