/* ============================================================
   bs-lite.css — 替代 Bootstrap 的最小实现
   只实现介绍页/附录页实际用到的类，全部限定在 .intro-embed 内，
   不会污染线上站点的 header / leftNav / footer。
   实现清单：12 栅格、accordion/collapse、container、text-*、my-3、btn
   ============================================================ */

/* ---------- 容器 ---------- */
.intro-embed .container{width:100%;max-width:100%;padding:0;margin:0 auto}

/* ---------- 12 栅格（grid 实现，无负边距） ---------- */
.intro-embed .row{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:24px;
}
.intro-embed .row.g-4{gap:24px}
.intro-embed .row.g-lg-5{gap:24px}
.intro-embed .row.justify-content-center{justify-content:center}
.intro-embed .row.align-items-start{align-items:start}

.intro-embed .col-md-4{grid-column:span 4}
.intro-embed .col-md-6{grid-column:span 6}
.intro-embed .col-md-8{grid-column:span 8}
.intro-embed .col-lg-5{grid-column:span 5}
.intro-embed .col-lg-7{grid-column:span 7}
.intro-embed .col-lg-10,
.intro-embed .col-lg-11{grid-column:span 12}

@media (max-width:991.98px){
  .intro-embed .col-md-4,
  .intro-embed .col-md-6,
  .intro-embed .col-md-8,
  .intro-embed .col-lg-5,
  .intro-embed .col-lg-7{grid-column:span 12}
}
@media (max-width:575.98px){
  .intro-embed .row,
  .intro-embed .row.g-4,
  .intro-embed .row.g-lg-5{gap:16px}
}

/* ---------- 工具类 ---------- */
.intro-embed .text-center{text-align:center}
.intro-embed .text-muted{color:#7C899E}
.intro-embed .my-3{margin-top:16px;margin-bottom:16px}
.intro-embed .fs-none{display:none}

/* ---------- 按钮 ---------- */
.intro-embed .btn{
  display:inline-block;
  font-family:inherit;font-weight:700;text-align:center;
  text-decoration:none;cursor:pointer;
  border:1px solid transparent;border-radius:8px;
  transition:background .16s,border-color .16s,transform .16s;
  -webkit-user-select:none;user-select:none;
}
.intro-embed .btn-primary{
  background:#C8601A;border-color:#C8601A;color:#fff;
}
.intro-embed .btn-primary:hover{background:#D96E28;border-color:#D96E28;color:#fff}
.intro-embed .btn-primary:active{transform:translateY(1px)}
.intro-embed .btn-xl{padding:15px 32px;font-size:16px;font-weight:700;letter-spacing:.03em;line-height:1.25}

/* ---------- 折叠 / 手风琴 ---------- */
.intro-embed .collapse{display:none}
.intro-embed .collapse.show{display:block}
.intro-embed .collapsing{position:relative;height:0;overflow:hidden;transition:height .22s ease}

/* 箭头的旋转靠 .collapsed 切换，样式由 about_intro.css 提供；
   这里只兜底一个旋转方向，防止图标缺失 */
.intro-embed .accordion-button::after{
  content:"";display:inline-block;flex:0 0 auto;
  width:8px;height:8px;margin-left:auto;
  border-right:1.6px solid currentColor;border-bottom:1.6px solid currentColor;
  transform:rotate(45deg) translate(-2px,-2px);
  transition:transform .18s;
}
.intro-embed .accordion-button.collapsed::after{
  transform:rotate(-45deg);
}

/* accordion-button 基础重置（原来依赖 Bootstrap，去掉后按钮露出浏览器默认 2px outset 边框、宽度只有内容宽） */
.intro-embed .accordion-header{margin:0}
.intro-embed .accordion-button{
  display:flex!important;align-items:center;gap:12px;
  width:100%!important;border:0!important;background:transparent!important;
  text-align:left;cursor:pointer;box-shadow:none!important;
  padding:14px 16px!important;font-family:inherit;
}
.intro-embed .accordion-button:focus{outline:0}
.intro-embed .accordion-button:focus-visible{outline:2px solid #C8601A;outline-offset:-2px}