/* ============================================================
   故宫三大殿 · 排水图鉴  —  红金主题样式
   配色：朱红 #8c1f1f / 描金 #c9a227 / 米底 #f6efe2
   ============================================================ */

:root {
  --red-deep: #6e1414;   /* 深朱红 */
  --red: #8c1f1f;        /* 故宫红 */
  --red-soft: #a83232;
  --gold: #c9a227;       /* 描金 */
  --gold-bright: #e8c558;
  --paper: #f6efe2;      /* 米黄纸底 */
  --paper-2: #efe5d2;
  --ink: #2a2018;        /* 墨色正文 */
  --ink-soft: #5a4a3a;
  --line: rgba(201, 162, 39, 0.45);
  --shadow: 0 6px 24px rgba(58, 30, 10, 0.18);
  --sidebar-w: 320px;
  --header-h: 78px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    radial-gradient(circle at 20% 10%, rgba(201,162,39,0.06), transparent 40%),
    radial-gradient(circle at 80% 90%, rgba(140,31,31,0.05), transparent 45%);
  line-height: 1.85;
  font-size: 17px;
}

/* ---------- 顶部横幅 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  height: var(--header-h);
  background: linear-gradient(135deg, var(--red-deep), var(--red));
  border-bottom: 3px solid var(--gold);
  box-shadow: var(--shadow);
}
.header-inner {
  max-width: 1500px;
  margin: 0 auto;
  height: 100%;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand { display: flex; align-items: center; gap: 16px; }
.brand-seal {
  width: 50px; height: 50px;
  display: grid; place-items: center;
  background: var(--gold);
  color: var(--red-deep);
  font-size: 28px; font-weight: 900;
  border-radius: 6px;
  box-shadow: inset 0 0 0 2px rgba(110,20,20,0.5);
}
.brand-text h1 {
  margin: 0; font-size: 24px; font-weight: 900;
  color: #fff5e0; letter-spacing: 2px;
}
.brand-text p {
  margin: 2px 0 0; font-size: 13px; color: var(--gold-bright); letter-spacing: 1px;
}

/* ---------- 侧栏开关按钮 ---------- */
.sidebar-toggle, .sidebar-reveal {
  font-family: inherit;
  cursor: pointer;
  border: 1px solid var(--gold);
  background: rgba(0,0,0,0.15);
  color: var(--gold-bright);
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 14px;
  transition: all .2s ease;
  white-space: nowrap;
}
.sidebar-toggle:hover, .sidebar-reveal:hover { background: var(--gold); color: var(--red-deep); }
.sidebar-reveal {
  position: fixed;
  right: 16px; top: 50%;
  transform: translateY(-50%);
  z-index: 25;
  background: var(--red);
  box-shadow: var(--shadow);
}

/* ---------- 阅读进度条 ---------- */
.progress-track {
  position: sticky; top: var(--header-h);
  height: 3px; z-index: 29;
  background: transparent;
}
.progress-bar {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--gold), var(--gold-bright));
  transition: width .1s linear;
}

/* ---------- 布局 ---------- */
.layout {
  display: flex;
  align-items: flex-start;
  max-width: 1500px;
  margin: 0 auto;
  padding: 28px;
  gap: 28px;
}
.content {
  flex: 1 1 auto;
  min-width: 0;
  position: relative;
  background: #fffdf8;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 36px 44px;
  box-shadow: var(--shadow);
}
.content::before {
  /* 回纹感内描边 */
  content: "";
  display: block;
  height: 8px;
  margin: -36px -44px 28px;
  border-radius: 10px 10px 0 0;
  background:
    repeating-linear-gradient(45deg, var(--gold) 0 6px, transparent 6px 12px) ,
    var(--red);
  background-blend-mode: overlay;
  opacity: .9;
}

/* ---------- 章节 ---------- */
.chapter { scroll-margin-top: calc(var(--header-h) + 20px); margin-bottom: 18px; }
.chapter-title {
  font-size: 27px; font-weight: 900; color: var(--red);
  border-left: 6px solid var(--gold);
  padding-left: 14px; margin: 30px 0 14px;
  display: flex; align-items: baseline; gap: 12px;
}
.chapter-title .num {
  font-size: 18px; color: var(--gold);
  border: 1px solid var(--gold); border-radius: 4px;
  padding: 1px 8px;
}
.sub-title {
  font-size: 20px; color: var(--red-soft);
  margin: 24px 0 8px; font-weight: 600;
  border-bottom: 1px dashed var(--line); padding-bottom: 4px;
}
.lead { font-size: 18px; color: var(--ink-soft); }
strong { color: var(--red); }

.fact-list { padding-left: 0; list-style: none; }
.fact-list li {
  background: var(--paper-2);
  border-left: 3px solid var(--gold);
  margin: 8px 0; padding: 8px 14px; border-radius: 4px;
}
.fact-list b { color: var(--red); }

/* 正文内可点术语 */
term {
  color: var(--red);
  border-bottom: 1px dotted var(--gold);
  cursor: help;
  font-weight: 600;
}

/* ---------- 图片占位 ---------- */
.img-placeholder {
  margin: 20px 0;
  min-height: 240px;
  border: 2px dashed var(--line);
  border-radius: 10px;
  background:
    repeating-linear-gradient(135deg, rgba(201,162,39,0.06) 0 12px, transparent 12px 24px),
    var(--paper);
  display: grid; place-items: center;
  position: relative;
}
.img-placeholder::after {
  content: attr(data-label);
  position: absolute; top: 10px; left: 14px;
  font-size: 12px; color: var(--ink-soft); letter-spacing: 1px;
}
.ph-hint { color: var(--gold); font-size: 15px; opacity: .85; }

/* ---------- 三维模型舞台 ---------- */
.model-stage { margin: 18px 0; }
.model-canvas {
  width: 100%; height: 440px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: linear-gradient(180deg, #f3ecdd, #e7dcc4);
  position: relative; overflow: hidden;
}
.model-fallback {
  position: absolute; inset: 0;
  display: grid; place-content: center; text-align: center;
  color: var(--ink-soft); gap: 6px;
}
.model-toolbar {
  display: flex; flex-wrap: wrap; gap: 8px; align-items: center;
  margin-top: 12px;
}
.mini-btn {
  font-family: inherit; cursor: pointer;
  border: 1px solid var(--gold); background: #fffdf8;
  color: var(--red); padding: 6px 12px; border-radius: 20px;
  font-size: 13px; transition: all .15s ease;
}
.mini-btn:hover { background: var(--paper-2); }
.mini-btn.off { opacity: .4; text-decoration: line-through; }
.model-tip { margin-left: auto; font-size: 12px; color: var(--ink-soft); }
.model-note { font-size: 12.5px; }
.muted { color: var(--ink-soft); font-size: 13px; }
code {
  background: var(--paper-2); padding: 1px 6px; border-radius: 4px;
  font-family: ui-monospace, "Cascadia Code", monospace; color: var(--red-soft);
}

/* ============================================================
   右侧边栏
   ============================================================ */
.sidebar {
  flex: 0 0 var(--sidebar-w);
  width: var(--sidebar-w);
  position: sticky;
  top: calc(var(--header-h) + 20px);
  max-height: calc(100vh - var(--header-h) - 40px);
  background: linear-gradient(180deg, #fffdf8, var(--paper));
  border: 1px solid var(--gold);
  border-radius: 10px;
  box-shadow: var(--shadow);
  transition: transform .35s cubic-bezier(.4,0,.2,1), margin .35s ease, opacity .25s ease;
  overflow: hidden;
}
/* 隐藏状态：移出可视区 */
.layout.sidebar-hidden .sidebar {
  transform: translateX(calc(var(--sidebar-w) + 40px));
  opacity: 0;
  margin-right: calc(var(--sidebar-w) * -1 - 28px);
  pointer-events: none;
}
.sidebar-scroll { max-height: 100%; overflow-y: auto; padding: 18px; }
.sidebar-scroll::-webkit-scrollbar { width: 8px; }
.sidebar-scroll::-webkit-scrollbar-thumb { background: var(--line); border-radius: 4px; }

.panel {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 16px;
  margin-bottom: 16px;
  background: #fffdf8;
}
.panel-title {
  margin: 0 0 8px; font-size: 16px; font-weight: 900; color: var(--red);
  display: flex; align-items: center; gap: 8px;
}
.panel-title::before {
  content: "❖"; color: var(--gold); font-size: 14px;
}
.panel-desc { margin: 0 0 10px; font-size: 12.5px; color: var(--ink-soft); }

/* 目录导航 */
.toc { display: flex; flex-direction: column; gap: 2px; }
.toc-link {
  text-decoration: none; color: var(--ink);
  padding: 7px 10px; border-radius: 6px; font-size: 14.5px;
  border-left: 3px solid transparent;
  transition: all .15s ease;
}
.toc-link.sub { font-size: 13px; color: var(--ink-soft); padding-left: 22px; }
.toc-link:hover { background: var(--paper-2); }
.toc-link.active {
  background: var(--red); color: #fff5e0;
  border-left-color: var(--gold);
  font-weight: 600;
}

/* 图层开关 */
.layer-list { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 8px; }
.layer-list label {
  display: flex; align-items: center; gap: 9px;
  font-size: 14px; cursor: pointer;
}
.layer-list input { width: 16px; height: 16px; accent-color: var(--red); }

/* 知识卡片 */
.cards { display: flex; flex-direction: column; gap: 8px; }
.card {
  border: 1px solid var(--line); border-radius: 8px; overflow: hidden;
  background: #fffdf8;
}
.card-head {
  width: 100%; text-align: left; cursor: pointer;
  font-family: inherit; font-size: 14.5px; font-weight: 600; color: var(--red);
  background: var(--paper-2); border: none; padding: 10px 12px;
  display: flex; justify-content: space-between; align-items: center;
}
.card-head .caret { transition: transform .2s ease; color: var(--gold); }
.card.open .card-head .caret { transform: rotate(90deg); }
.card-body {
  max-height: 0; overflow: hidden;
  transition: max-height .3s ease;
  padding: 0 12px;
  font-size: 13.5px; color: var(--ink-soft);
}
.card.open .card-body { max-height: 320px; padding: 10px 12px; }
.card-body b { color: var(--red); }

/* 页脚 */
.site-footer {
  margin-top: 30px; padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: 12.5px; color: var(--ink-soft); text-align: center;
}

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .layout { flex-direction: column; }
  .sidebar {
    position: fixed; right: 0; top: var(--header-h);
    width: min(86vw, 340px); max-height: calc(100vh - var(--header-h));
    z-index: 40; border-radius: 10px 0 0 10px;
  }
  .layout.sidebar-hidden .sidebar { transform: translateX(105%); margin-right: 0; }
}
@media (max-width: 600px) {
  .content { padding: 24px 18px; }
  .content::before { margin: -24px -18px 20px; }
  .brand-text p { display: none; }
  .model-canvas { height: 320px; }
  body { font-size: 16px; }
}

/* ============================================================
   传统纹样装饰
   ============================================================ */

/* 云纹分隔线 */
.cloud-divider {
  height: 30px; margin: 30px 0 12px;
  background: center / contain no-repeat url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='260' height='30'%3E%3Cg fill='none' stroke='%23c9a227' stroke-width='1.5'%3E%3Cpath d='M12 15 H104'/%3E%3Cpath d='M156 15 H248'/%3E%3Cpath d='M130 5 c-9 0 -13 7 -6 11 c-7 2 -3 10 6 8 c8 3 15 -3 11 -10 c7 -2 3 -11 -6 -9 c-4 -4 -9 -2 -10 1 z' fill='%23c9a227' fill-opacity='0.18'/%3E%3C/g%3E%3C/svg%3E");
  opacity: .85;
}

/* 四角云纹角饰 */
.content-corners { position: absolute; inset: 0; pointer-events: none; z-index: 1; }
.content-corners .c {
  position: absolute; width: 42px; height: 42px;
  background: no-repeat url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='42' height='42'%3E%3Cg fill='none' stroke='%23c9a227' stroke-width='2'%3E%3Cpath d='M3 39 V12 a9 9 0 0 1 9 -9 H39'/%3E%3Cpath d='M9 39 V16 a5 5 0 0 1 5 -5 H39' opacity='.55'/%3E%3C/g%3E%3Ccircle cx='15' cy='15' r='2.6' fill='%23c9a227'/%3E%3C/svg%3E");
}
.content-corners .tl { top: 14px; left: 14px; }
.content-corners .tr { top: 14px; right: 14px; transform: scaleX(-1); }
.content-corners .bl { bottom: 14px; left: 14px; transform: scaleY(-1); }
.content-corners .br { bottom: 14px; right: 14px; transform: scale(-1, -1); }

/* 印章式章节序号 */
.chapter-title .num {
  background: var(--red);
  color: var(--gold-bright);
  border: 1px solid var(--gold);
  border-radius: 4px;
  padding: 2px 10px;
  font-size: 16px;
  box-shadow: inset 0 0 0 1px rgba(201,162,39,.45);
}

/* 面板标题回纹下划线 */
.panel-title {
  background: repeating-linear-gradient(90deg, var(--gold) 0 5px, transparent 5px 10px) bottom left / 100% 3px no-repeat;
  padding-bottom: 7px;
}

/* 古今对照表 */
.compare { width: 100%; border-collapse: collapse; margin: 12px 0 4px; font-size: 14px; }
.compare th, .compare td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
.compare th { background: var(--red); color: #fff5e0; font-weight: 600; }
.compare tbody tr:nth-child(even) { background: var(--paper-2); }
.compare td:first-child { color: var(--red); font-weight: 600; white-space: nowrap; }

@media (max-width: 600px) {
  .content-corners { display: none; }
  .compare { font-size: 12.5px; }
  .compare th, .compare td { padding: 5px 6px; }
}