:root {
  --sidebar-width: 280px;
  --sidebar-bg: #ffffff;
  --sidebar-border: #cccccc;
  --sidebar-text: #333333;
  --sidebar-text-muted: #444444;
  --sidebar-hover: #f0f0f0;
  --sidebar-active-bg: #e8e8e8;
  --sidebar-active-text: #333333;
}

.page-shell {
  display: block;
  min-height: 100vh;
}

.file-sidebar {
  width: var(--sidebar-width);
  background: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  color: var(--sidebar-text);
  height: 100vh;
  position: fixed;
  top: 0;
  left: 0;
  overflow-y: auto;
  font-family: "Anaheim", sans-serif;
  font-size: 0.85rem;
  padding-bottom: 24px;
  box-shadow: 2px 0 8px rgba(0, 0, 0, 0.12);
  transform: translateX(-100%);
  transition: transform 0.2s ease;
  z-index: 15;
}

body.sidebar-open .file-sidebar {
  transform: translateX(0);
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 16px 12px;
  border-bottom: 1px solid var(--sidebar-border);
  font-weight: 600;
  position: sticky;
  top: 0;
  background: var(--sidebar-bg);
  z-index: 1;
}

.tree-list {
  list-style: none;
  margin: 0;
  padding: 8px;
}

.tree-root {
  padding: 8px;
}

.tree-root .tree-list {
  padding: 2px 0 6px 20px;
  border-left: 1px solid var(--sidebar-border);
  margin-left: 10px;
}

.tree-item {
  margin: 1px 0;
}

.tree-dir,
.tree-file {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 5px 8px;
  border-radius: 0;
  cursor: pointer;
  color: var(--sidebar-text);
  text-decoration: none;
  white-space: normal;
  line-height: 1.3;
}

summary.tree-dir {
  list-style: none;
  font-weight: 600;
}

summary.tree-dir::-webkit-details-marker {
  display: none;
}

.tree-dir:hover,
.tree-file:hover {
  background: var(--sidebar-hover);
}

.tree-file.active {
  background: var(--sidebar-active-bg);
  color: var(--sidebar-active-text);
  font-weight: 600;
}

.tree-file-disabled {
  color: var(--sidebar-text-muted);
  cursor: default;
}

.tree-file-disabled:hover {
  background: none;
}

.tree-caret {
  flex-shrink: 0;
  transition: transform 0.15s ease;
  color: var(--sidebar-text-muted);
}

details[open] > summary .tree-caret {
  transform: rotate(90deg);
}

.page-main {
  min-width: 0;
}

.sidebar-toggle-btn {
  position: fixed;
  bottom: 20px;
  left: 20px;
  z-index: 20;
  background: var(--surface, #fff);
  border: 1px solid var(--sidebar-border);
  border-radius: 0;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1rem;
}