/* Lumira subtopic rail - shared, decoupled. One file controls every subtopic nav.
   Accent per subject via [data-subject]. A change on any single page cannot affect this. */
.subtopic-nav{display:none !important;} /* hide the old per-page nav; the rail replaces it */
.lum-rail{--rc:#6366F1;--rct:#EEF2FF;--rline:#E2E8F0;--rsurf:#fff;--rmuted:#64748B;--rfaint:#94A3B8;--rink:#0F172A;--rdone:#16A34A;
  font-family:'DM Sans',system-ui,sans-serif;margin-bottom:28px;}
.lum-rail[data-subject="chem"]{--rc:#10B981;--rct:#ECFDF5;}
.lum-rail .lr-label{font-family:'DM Mono',monospace;font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:var(--rfaint);margin-bottom:9px;}
.lum-rail .lr-track{display:flex;gap:8px;overflow-x:auto;padding-bottom:4px;}
.lum-rail .lr-seg{flex:0 0 auto;display:flex;align-items:center;gap:9px;padding:8px 14px;border-radius:999px;background:var(--rsurf);
  border:.5px solid var(--rline);color:var(--rmuted);font-size:13px;cursor:pointer;white-space:nowrap;
  transition:color .2s,border-color .2s,background .2s;}
.lum-rail .lr-seg:hover{color:var(--rink);}
.lum-rail .lr-seg .lr-n{font-family:'DM Mono',monospace;font-size:12px;color:var(--rfaint);}
.lum-rail .lr-seg.is-current{background:var(--rct);border-color:var(--rc);color:var(--rc);font-weight:500;}
.lum-rail .lr-seg.is-current .lr-n{color:var(--rc);}
.lum-rail .lr-seg.is-done .lr-n{color:var(--rdone);}
.lum-rail .lr-seg:focus-visible{outline:1.5px solid var(--rc);outline-offset:2px;}
.lum-rail .lr-bar{margin-top:14px;display:flex;align-items:center;gap:12px;}
.lum-rail .lr-bar .lr-track-bar{flex:1;height:4px;border-radius:2px;background:var(--rline);overflow:hidden;min-width:0;}
.lum-rail .lr-bar .lr-fill{display:block;height:100%;background:var(--rc);border-radius:2px;}
.lum-rail .lr-bar .lr-pct{font-family:'DM Mono',monospace;font-size:11px;color:var(--rfaint);white-space:nowrap;}