:root {
  --bg: #fafafa;
  --bg-card: #ffffff;
  --bg-sidebar: #f4f5f7;
  --fg: #1f2328;
  --fg-muted: #6e7681;
  --border: #e5e7eb;
  --primary: #2b6cb0;
  --primary-light: #ebf4ff;
  --accent: #d97706;
  --shadow: 0 1px 3px rgba(0,0,0,0.06);
  --radius: 6px;
  --topbar-h: 52px;
  --sidebar-w: 280px;
  --panel-w: 400px;
  --font-sans: -apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --font-mono: "JetBrains Mono","SF Mono",Consolas,"Liberation Mono",Menlo,monospace;
}
[data-theme="dark"] {
  --bg: #0d1117;
  --bg-card: #161b22;
  --bg-sidebar: #010409;
  --fg: #e6edf3;
  --fg-muted: #8b949e;
  --border: #30363d;
  --primary: #58a6ff;
  --primary-light: #1f6feb33;
  --accent: #f0883e;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
}
* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;  /* shell 整页固定 */
}

/* 顶栏 */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--topbar-h);
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center;
  padding: 0 16px;
  z-index: 100;
  gap: 12px;
}
.brand {
  display: flex; align-items: center; gap: 8px;
  text-decoration: none; color: var(--fg);
  font-weight: 600; font-size: 15px;
  white-space: nowrap;
}
.brand-icon { font-size: 18px; }
.menu-toggle {
  display: none;
  background: transparent; border: 0;
  font-size: 20px; cursor: pointer; color: var(--fg);
  padding: 4px 8px;
}
.topbar-tools { margin-left: auto; display: flex; align-items: center; gap: 8px; }
.search-wrap { position: relative; }
#searchInput {
  width: 260px; padding: 6px 12px;
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--bg); color: var(--fg);
  font-size: 13px; outline: none;
  transition: border-color 0.15s;
}
#searchInput:focus { border-color: var(--primary); }
.theme-toggle {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 5px 8px;
  cursor: pointer; font-size: 16px; color: var(--fg);
}
.theme-toggle:hover { border-color: var(--primary); }

/* 侧边栏 */
.sidebar {
  position: fixed;
  top: var(--topbar-h); left: 0; bottom: 0;
  width: var(--sidebar-w);
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 12px 0;
  font-size: 14px;
  z-index: 50;
}
.nav ul { list-style: none; margin: 0; padding: 0; }
.nav > ul { padding: 0 8px; }
.nav-mod { margin: 4px 0; }
.nav-mod > summary {
  list-style: none; cursor: pointer;
  border-radius: var(--radius);
  user-select: none;
  display: flex; align-items: center; gap: 6px;
  padding: 6px 10px 6px 12px;
  position: relative;
}
.nav-mod > summary::-webkit-details-marker { display: none; }
/* +/- 折叠箭头 */
.nav-mod > summary::before {
  content: "▶";
  display: inline-block;
  width: 14px;
  font-size: 10px;
  color: var(--fg-muted);
  transition: transform 0.15s;
  flex-shrink: 0;
  text-align: center;
}
.nav-mod[open] > summary::before {
  transform: rotate(90deg);
  color: var(--primary);
}
.mod-summary:hover { background: var(--primary-light); }
.mod-icon { font-size: 16px; }
.mod-title { font-weight: 600; }

/* 子项缩进 + 引导线 */
.subnav {
  list-style: none !important;
  padding-left: 12px !important;
  padding-top: 6px;
  padding-bottom: 8px;
  margin-left: 5px !important;
  border-left: 2px solid var(--border);
}
.subnav li { margin: 1px 0; }
.subnav .nav-item {
  padding: 5px 10px !important;
  display: block;
}

/* 文件级别（第二级） */
.nav-file {
  margin: 1px 0;
}
.nav-file > .file-summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
  padding: 4px 8px 4px 10px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 13px;
  font-weight: 500;
}
.nav-file > .file-summary::before {
  content: "▶";
  display: inline-block;
  width: 10px;
  font-size: 9px;
  color: var(--fg-muted);
  transition: transform 0.15s;
  flex-shrink: 0;
  text-align: center;
}
.nav-file[open] > .file-summary::before {
  transform: rotate(90deg);
  color: var(--primary);
}
.nav-file > .file-summary:hover { background: var(--primary-light); }
.file-title { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* 标题级别（第三级） */
.subnav-head {
  list-style: none !important;
  padding-left: 16px !important;
  margin-left: 6px !important;
  border-left: 1px dashed var(--border);
  padding-top: 2px;
  padding-bottom: 2px;
}
.nav-head-item {
  display: block;
  padding: 3px 8px !important;
  font-size: 12.5px;
  color: var(--fg-muted);
  text-decoration: none;
  border-radius: 3px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.nav-head-item:hover {
  color: var(--primary);
  background: var(--primary-light);
}

/* 键盘焦点高亮 */
.summary-mod:focus,
.summary-mod:focus-visible,
.mod-summary:focus,
.mod-summary:focus-visible,
.file-summary:focus,
.file-summary:focus-visible,
.nav-item:focus,
.nav-item:focus-visible,
.nav-head-item:focus,
.nav-head-item:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: -2px;
  background: var(--primary-light);
}
.nav-item {
  display: flex; align-items: center; gap: 6px;
  padding: 5px 10px;
  text-decoration: none; color: var(--fg);
  border-radius: var(--radius);
  font-weight: 400; font-size: 13.5px;
}
.nav-item:hover { background: var(--primary-light); }
.nav-item.active {
  background: var(--primary); color: white;
  font-weight: 500;
}
.item-icon { font-size: 13px; }

/* 主区（iframe）— 始终为 sidebar-w 到 viewport-panel-w，
   即使面板隐藏也保留这个空间，让 article 在此范围内居中显示 */
.main {
  position: fixed;
  top: var(--topbar-h);
  left: var(--sidebar-w);
  right: var(--panel-w);
  bottom: 0;
  background: var(--bg);
  z-index: 1;
}
.main iframe {
  width: 100%; height: 100%;
  border: 0;
  background: var(--bg-card);
}

/* 右侧面板 - 默认展开 */
.side-panel {
  position: fixed;
  top: var(--topbar-h);
  right: 0;
  bottom: 0;
  width: var(--panel-w);
  max-width: 90vw;
  background: var(--bg-card);
  border-left: 1px solid var(--border);
  box-shadow: -4px 0 20px rgba(0,0,0,0.15);
  z-index: 60;
  display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.25s ease-out;
}
.side-panel.open {
  transform: translateX(0);
}
body.panel-collapsed .side-panel {
  transform: translateX(100%);
}
.side-panel-header {
  border-bottom: 1px solid var(--border);
  display: flex; align-items: stretch; gap: 0;
  background: var(--bg-sidebar);
  flex-shrink: 0;
  min-height: 40px;
}
.panel-tabs {
  flex: 1;
  display: flex;
  align-items: stretch;
  overflow-x: auto;
}
.panel-tab {
  background: transparent; border: 0;
  padding: 0 14px;
  font-size: 13px;
  cursor: pointer;
  color: var(--fg-muted);
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: all 0.15s;
}
.panel-tab:hover { color: var(--fg); }
.panel-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}
.side-panel-close {
  background: transparent; border: 0;
  font-size: 16px; color: var(--fg-muted);
  cursor: pointer; padding: 0 14px;
  border-left: 1px solid var(--border);
  transition: color 0.15s;
}
.side-panel-close:hover { color: var(--accent); }

.panel-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.panel-content[hidden] { display: none; }

.side-panel-body {
  flex: 1; overflow-y: auto;
  padding: 8px 0;
}

/* 面板 toggle 按钮（左侧边缘） */
.panel-toggle {
  position: fixed;
  top: 50%;
  right: var(--panel-w);
  transform: translateY(-50%);
  z-index: 70;
  width: 24px; height: 60px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-right: 0;
  border-radius: var(--radius) 0 0 var(--radius);
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  font-size: 14px;
  color: var(--fg-muted);
  transition: right 0.25s ease-out, color 0.15s;
}
.panel-toggle:hover { color: var(--primary); border-color: var(--primary); }
/* 面板收起时按钮保持在原位置（panel 边缘） */
body.panel-collapsed .panel-toggle {
  right: var(--panel-w);
}

/* 搜索结果（在面板内） */
.search-result {
  display: block;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
  color: var(--fg);
  cursor: pointer;
}
.search-result:last-child { border-bottom: 0; }
.search-result:hover, .search-result.active {
  background: var(--primary-light);
}
.search-result-title { font-weight: 600; font-size: 14px; }
.search-result-meta { font-size: 12px; color: var(--fg-muted); margin-top: 2px; }
.search-result-excerpt {
  font-size: 12px; color: var(--fg-muted);
  margin-top: 4px; line-height: 1.4;
  display: -webkit-box; -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.search-result mark {
  background: rgba(251, 191, 36, 0.35);
  color: inherit;
  padding: 0 2px; border-radius: 2px;
  font-weight: 600;
}
[data-theme="dark"] .search-result mark {
  background: rgba(251, 191, 36, 0.4);
}
.side-panel-empty {
  padding: 32px 16px; text-align: center;
  color: var(--fg-muted); font-size: 13px;
}

/* 搜索历史下拉 */
.search-history {
  position: absolute; top: 100%; left: 0; right: 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 6px 18px rgba(0,0,0,0.12);
  margin-top: 4px;
  z-index: 200;
  max-height: 320px; overflow-y: auto;
}
.search-history-header {
  padding: 8px 12px;
  font-size: 11px; color: var(--fg-muted);
  border-bottom: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  text-transform: uppercase; letter-spacing: 0.5px;
}
.search-history-clear {
  background: transparent; border: 0;
  color: var(--fg-muted); cursor: pointer;
  font-size: 11px; padding: 2px 6px;
  border-radius: 3px;
}
.search-history-clear:hover { color: var(--accent); background: var(--bg-sidebar); }
.search-history-item {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 12px; cursor: pointer;
  font-size: 13px;
  border-bottom: 1px solid var(--border);
}
.search-history-item:last-child { border-bottom: 0; }
.search-history-item:hover, .search-history-item.active { background: var(--primary-light); }
.search-history-icon { color: var(--fg-muted); font-size: 14px; }
.search-history-empty {
  padding: 16px; text-align: center;
  color: var(--fg-muted); font-size: 12px;
}

/* 高亮浮动工具条 */
.highlight-bar {
  position: fixed;
  bottom: 20px; left: 50%;
  transform: translateX(-50%);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 8px 6px 16px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.15);
  z-index: 150;
  display: flex; align-items: center; gap: 8px;
  font-size: 13px;
  animation: hl-bar-in 0.25s ease-out;
}
@keyframes hl-bar-in {
  from { transform: translate(-50%, 20px); opacity: 0; }
  to { transform: translate(-50%, 0); opacity: 1; }
}
.highlight-text { color: var(--fg); }
.highlight-text b { color: var(--accent); }
.hl-btn {
  background: transparent; border: 1px solid var(--border);
  border-radius: 999px; padding: 4px 10px;
  font-size: 12px; cursor: pointer; color: var(--fg);
}
.hl-btn:hover { background: var(--primary-light); border-color: var(--primary); }
.hl-close { border-color: transparent; color: var(--fg-muted); }
.hl-close:hover { background: rgba(239, 68, 68, 0.1); border-color: #ef4444; color: #ef4444; }

/* 滚动条 */
.sidebar::-webkit-scrollbar,
.side-panel-body::-webkit-scrollbar,
.search-history::-webkit-scrollbar { width: 8px; height: 8px; }
.sidebar::-webkit-scrollbar-thumb,
.side-panel-body::-webkit-scrollbar-thumb,
.search-history::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
.sidebar::-webkit-scrollbar-thumb:hover,
.side-panel-body::-webkit-scrollbar-thumb:hover { background: var(--fg-muted); }

/* 移动端 */
@media (max-width: 900px) {
  .menu-toggle { display: inline-block; }
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.2s;
    box-shadow: 2px 0 12px rgba(0,0,0,0.1);
  }
  .sidebar.open { transform: translateX(0); }
  .main { left: 0; }
  .panel-toggle { right: 12px; }
  body.panel-collapsed .panel-toggle { right: 12px; }
  #searchInput { width: 140px; }
}
@media (max-width: 480px) {
  .brand-text { display: none; }
  #searchInput { width: 100px; }
}