:root {
  --bg: #f6f6f1;
  --panel: #eceadf;
  --text: #1e1d18;
  --muted: #6a675d;
  --line: #d2cebf;
  --accent: #215f4c;
  --accent-soft: #d7ebe5;
  --error: #a12626;
  --danger: #8f2323;
  --font-ui: "IBM Plex Sans", "Avenir Next", "Segoe UI", sans-serif;
  --font-body: "Source Serif 4", "Georgia", serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: radial-gradient(circle at top right, #fcfaf3 0%, var(--bg) 45%, #eeecdf 100%);
  color: var(--text);
  font-family: var(--font-ui);
  min-height: 100%;
}

button,
input,
textarea {
  font: inherit;
}

.layout {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  border-right: 1px solid var(--line);
  background: linear-gradient(180deg, #f3f0e3 0%, var(--panel) 100%);
  padding: 1rem;
  overflow-y: auto;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  margin-bottom: 0.5rem;
}

.sidebar-header h1 {
  margin: 0;
  font-size: 1.2rem;
  letter-spacing: 0.02em;
}

.brand-link {
  color: inherit;
  text-decoration: none;
}

.brand-link:hover {
  text-decoration: underline;
}

.new-page {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 0.35rem;
  padding: 0.25rem 0.5rem;
}

.tree-root,
.tree-children {
  list-style: none;
  margin: 0;
  padding: 0;
}

.tree-children {
  margin-left: 1rem;
}

.tree-children.closed {
  display: none;
}

.tree-folder-row {
  display: flex;
  align-items: center;
  gap: 0.15rem;
}

.tree-toggle {
  border: 0;
  background: transparent;
  padding: 0.2rem 0.1rem;
  color: var(--text);
  cursor: pointer;
  border-radius: 0.2rem;
}

.tree-toggle:hover {
  background: #f3f0e3;
}

.tree-folder-link {
  display: block;
  color: var(--text);
  text-decoration: none;
  padding: 0.2rem 0.35rem;
  border-radius: 0.3rem;
  flex: 1;
}

.tree-page a {
  display: block;
  color: var(--text);
  text-decoration: none;
  padding: 0.2rem 0.35rem;
  border-radius: 0.3rem;
}

.tree-page a:hover,
.tree-page.active a,
.tree-folder-link:hover,
.tree-folder.active .tree-folder-link {
  background: var(--accent-soft);
  color: var(--accent);
}

.caret {
  display: inline-block;
  width: 1rem;
}

.content {
  padding: 1.25rem clamp(1rem, 3vw, 2.2rem);
}

.page-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 260px;
  gap: 1rem;
  align-items: start;
}

.page-toc {
  position: sticky;
  top: 1rem;
  border-left: 1px solid var(--line);
  padding-left: 0.7rem;
}

.page-toc h3 {
  margin: 0 0 0.5rem;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.page-toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.toc-link {
  display: block;
  color: var(--muted);
  text-decoration: none;
  border-radius: 0.25rem;
  padding-top: 0.12rem;
  padding-bottom: 0.12rem;
}

.toc-link:hover {
  color: var(--accent);
  background: var(--accent-soft);
}

.content-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.actions {
  display: flex;
  gap: 0.45rem;
}

.actions button,
.editor-toolbar button {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 0.35rem;
  padding: 0.3rem 0.7rem;
}

.actions .danger {
  border-color: #d7b7b7;
  color: var(--danger);
}

.editor-toolbar {
  margin-top: 1rem;
  display: flex;
  align-items: end;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.editor-toolbar label {
  display: grid;
  gap: 0.2rem;
  min-width: min(520px, 100%);
  flex: 1;
}

.editor-toolbar input {
  border: 1px solid var(--line);
  border-radius: 0.35rem;
  padding: 0.35rem 0.55rem;
}

.editor-layout {
  margin-top: 0.85rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.editor-pane,
.preview-pane {
  border: 1px solid var(--line);
  border-radius: 0.5rem;
  overflow: hidden;
  background: #fff;
}

.editor-pane h3,
.preview-pane h3 {
  margin: 0;
  padding: 0.6rem 0.8rem;
  font-size: 0.95rem;
  border-bottom: 1px solid var(--line);
  background: #f7f5ec;
}

#editor-input {
  width: 100%;
  min-height: 58vh;
  border: 0;
  resize: vertical;
  padding: 0.8rem;
  font-family: "IBM Plex Mono", "Menlo", monospace;
  line-height: 1.45;
}

#preview-content {
  min-height: 58vh;
  padding: 0.8rem;
}

.markdown-body {
  font-family: var(--font-body);
  line-height: 1.55;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3 {
  font-family: var(--font-ui);
}

.markdown-body pre {
  overflow-x: auto;
  background: #f8f8f3;
  border: 1px solid var(--line);
  border-radius: 0.3rem;
  padding: 0.5rem;
}

.markdown-body code {
  font-family: "IBM Plex Mono", "Menlo", monospace;
  font-size: 0.92em;
}

.virtual-folder {
  border: 1px solid var(--line);
  border-radius: 0.5rem;
  background: #fff;
  padding: 1rem;
  margin-top: 0.8rem;
}

.virtual-folder h2 {
  margin: 0 0 0.4rem;
  font-size: 1.1rem;
}

.virtual-folder-actions {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.virtual-folder-actions button {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 0.35rem;
  padding: 0.3rem 0.7rem;
}

.muted {
  color: var(--muted);
}

.error {
  color: var(--error);
  margin: 0;
  width: 100%;
}

@media (max-width: 980px) {
  .layout {
    grid-template-columns: 1fr;
    min-height: auto;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .editor-layout {
    grid-template-columns: 1fr;
  }

  .page-layout {
    grid-template-columns: 1fr;
  }

  .page-toc {
    position: static;
    border-left: 0;
    border-top: 1px solid var(--line);
    padding-left: 0;
    padding-top: 0.7rem;
  }

  #editor-input,
  #preview-content {
    min-height: 35vh;
  }
}