*{box-sizing:border-box;margin:0;padding:0;font-family:"Microsoft YaHei",sans-serif;}
body{
  background:#222;
  padding:1rem;
}
.wrap{
  max-width:1600px;
  width:96%;
  margin:0 auto;
  border:1px solid #ffffff60;
  border-radius:16px;
  padding:2px; /* iframe四周2px缝隙 */
  overflow:hidden;
}
.main-row{
  display:flex;
  gap:14px;
  height: calc(100vh - 2rem);
}
.toc-col{
  width:220px;
  background:#333;
  border-radius:8px;
  padding:12px;
  overflow-y:auto;
}
.toc-col h3{
  color:#fff;
  margin-bottom:12px;
  font-size:16px;
}
.toc-item{
  color:#ccc;
  padding:6px 8px;
  cursor:pointer;
  border-radius:4px;
  margin-bottom:4px;
  font-size:14px;
}
.toc-item:hover{
  background:#446;
  color:#fff;
}
.toc-item.active{
  background:#5577aa;
  color:#ffffff;
}
.frame-col{
  flex:1;
  display:flex;
}
iframe{
  width:100%;
  height:100%;
  border:none;
  border-radius:12px;
}

/* 补充少量样式，如果你yuyinT.css没有 */
.toc-header{
  margin-bottom:12px;
  padding-bottom:8px;
  border-bottom:1px solid #444;
}
.toc-header a{
  color:#ccc;
  margin-right:10px;
}
.toc-header a:hover{
  color:#fff;
}