html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  font-family: "ＭＳ Ｐゴシック", "MS PGothic", Arial, Helvetica, sans-serif;
  font-size: 10.5pt;
}
.manual-wrapper {
  display: -ms-flexbox;
  display: flex;
  height: 100%;
}
#nav {
  width: 320px;
  min-width: 200px;
  height: 100%;
  overflow: auto;
  border-right: 1px solid #ccc;
  background: #f8f8f8;
  box-sizing: border-box;
  padding: 8px 4px 8px 8px;
}
#nav-resizer {
  width: 5px;
  cursor: col-resize;
  background: #e0e0e0;
  flex-shrink: 0;
}
#nav-resizer:hover {
  background: #bbb;
}
/* リサイズ中のボディ状態 */
body.resizing {
  cursor: col-resize;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
}
#content-area {
  -ms-flex: 1;
  flex: 1;
  height: 100%;
  min-width: 0;
  overflow-y: auto;
}
#content {
  padding: 5px;
}
/* ─── ツリー ─── */
#nav ul {
  list-style: none;
  margin: 0;
  padding: 0 0 0 16px;
}
#nav > ul {
  padding-left: 0;
}
#nav li {
  margin: 1px 0;
  white-space: nowrap;
}
#nav a {
  color: #1111cc;
  text-decoration: none;
}
#nav a:visited {
  color: #993399;
}
#nav a:hover {
  color: #aa1111;
  text-decoration: underline;
}
#nav a.active {
  background: #cde;
  font-weight: bold;
}
.tree-toggle {
  display: inline-block;
  width: 16px;
  text-align: center;
  cursor: pointer;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
  color: #555;
  font-size: 8pt;
}
.tree-branch > .tree-toggle::before {
  content: "\25B6";
}
.tree-branch.open > .tree-toggle::before {
  content: "\25BC";
}
.tree-children {
  display: none;
}
.tree-branch.open > .tree-children {
  display: block;
}
/* コンテンツエリア プレースホルダ */
.content-message {
  padding: 20px;
}