/* 页面导航线：跟随正文滚动，图标与各栏目标题同一水平线，位置贴近正文左缘 */
#rail{position:absolute;top:0;left:0;width:0;height:0;z-index:30;--dot:40px}
#railLine{position:absolute;width:1px;left:-.5px;background:rgba(27,26,23,.16);z-index:1}
#railFill{position:absolute;width:3px;left:-1.5px;background:#E8872B;border-radius:9999px;transition:height .5s ease;z-index:1}
#rail .rail-dot{position:absolute;display:grid;place-items:center;width:var(--dot);height:var(--dot);border-radius:9999px;
  background:#fff;border:1.5px solid rgba(27,26,23,.18);color:rgba(27,26,23,.5);box-shadow:0 1px 3px rgba(27,26,23,.1);
  transition:background .25s,border-color .25s,color .25s,transform .25s,box-shadow .25s;z-index:2}
#rail .rail-dot svg{width:20px;height:20px}
#rail .rail-dot:hover{color:#1B1A17;border-color:rgba(27,26,23,.42)}
#rail .rail-dot.done{border-color:#E8872B;color:#B85F0C}
#rail .rail-dot.active{background:#E8872B;border-color:#E8872B;color:#fff;transform:scale(1.2);
  box-shadow:0 0 0 6px rgba(232,135,43,.24),0 10px 22px -8px rgba(184,95,12,.75)}