:root {
  --bg: #0f1117;
  --bg-soft: #161922;
  --bg-elev: #1c2030;
  --bg-input: #11141d;
  --border: #2a2f3e;
  --border-soft: #232838;
  --text: #e6e9f0;
  --text-dim: #9aa3b5;
  --text-faint: #6b7488;
  --accent: #6c5ce7;
  --accent-soft: #8b7bf0;
  --accent-bg: rgba(108, 92, 231, 0.16);
  --danger: #e5566f;
  --ok: #4ec9a8;
  --radius: 10px;
  --shadow: 0 8px 30px rgba(0, 0, 0, 0.35);
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}

.app { display: flex; height: 100vh; height: 100dvh; }

/* ---------- Sidebar ---------- */
.sidebar {
  width: 280px;
  flex-shrink: 0;
  background: var(--bg-soft);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  transition: margin-left 0.22s ease;
}
.app.sidebar-collapsed .sidebar { margin-left: -280px; }

.sidebar-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 14px 10px;
}
.brand { display: flex; align-items: center; gap: 9px; }
.brand-logo { border-radius: 7px; }
.brand-name { font-weight: 700; font-size: 16px; letter-spacing: 0.5px; }

.icon-btn {
  background: transparent; border: 1px solid var(--border);
  color: var(--text-dim); width: 30px; height: 30px; border-radius: 8px;
  cursor: pointer; font-size: 16px; line-height: 1;
}
.icon-btn:hover { color: var(--text); border-color: var(--accent); }

/* 收起侧栏时的浮动「展开」按钮：默认隐藏，仅在 sidebar-collapsed 时显示 */
.reveal-btn {
  display: none;
  margin-right: 4px; flex-shrink: 0;
}
.app.sidebar-collapsed .reveal-btn { display: inline-flex; align-items: center; justify-content: center; }

.sidebar-tools { display: flex; gap: 8px; padding: 0 14px 12px; }
.tool-btn {
  flex: 1; background: var(--accent); color: #fff; border: none;
  padding: 9px 10px; border-radius: 8px; cursor: pointer; font-size: 13px;
  font-weight: 600; transition: background 0.15s;
}
.tool-btn:hover { background: var(--accent-soft); }
.tool-btn.big { flex: none; padding: 12px 22px; font-size: 15px; margin-top: 6px; }

.tree-wrap { flex: 1; overflow-y: auto; padding: 4px 8px 12px; }
.tree, .tree ul { list-style: none; margin: 0; padding: 0; }
.tree ul { padding-left: 16px; border-left: 1px dashed var(--border-soft); margin-left: 11px; }

.tree-item {
  display: flex; align-items: center; gap: 6px;
  padding: 7px 8px; border-radius: 8px; cursor: pointer;
  color: var(--text-dim); user-select: none; position: relative;
}
.tree-item:hover { background: var(--bg-elev); color: var(--text); }
.tree-item.active { background: var(--accent-bg); color: var(--text); }
.tree-item.active::before {
  content: ""; position: absolute; left: -1px; top: 6px; bottom: 6px;
  width: 3px; border-radius: 3px; background: var(--accent);
}
.tree-item .ti-icon { width: 16px; text-align: center; flex-shrink: 0; font-size: 13px; }
.tree-item .ti-label { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.tree-item .ti-actions { display: none; gap: 2px; }
.tree-item:hover .ti-actions { display: flex; }
.ti-actions button {
  background: transparent; border: none; color: var(--text-faint);
  cursor: pointer; font-size: 13px; padding: 1px 4px; border-radius: 5px;
}
.ti-actions button:hover { color: var(--text); background: var(--bg-input); }
.ti-actions button.del:hover { color: var(--danger); }

.tree-empty { color: var(--text-faint); font-size: 12.5px; padding: 12px 14px; line-height: 1.6; }

.sidebar-foot { display: flex; gap: 8px; padding: 10px 14px; border-top: 1px solid var(--border); }
.ghost-btn {
  flex: 1; background: transparent; border: 1px solid var(--border);
  color: var(--text-dim); padding: 7px; border-radius: 8px; cursor: pointer; font-size: 12.5px;
}
.ghost-btn:hover { color: var(--text); border-color: var(--accent); }

/* ---------- Main ---------- */
.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }

.toolbar {
  background: var(--bg-soft); border-bottom: 1px solid var(--border);
  padding: 10px 14px; display: flex; flex-direction: column; gap: 10px;
}
.doc-title-wrap { display: flex; align-items: center; gap: 12px; }
.doc-title {
  background: transparent; border: none; color: var(--text);
  font-size: 18px; font-weight: 700; padding: 4px 2px; flex: 1; min-width: 0;
}
.doc-title:focus { outline: none; }
.save-state { font-size: 12px; color: var(--text-faint); white-space: nowrap; }
.save-state.saving { color: var(--accent-soft); }
.save-state.saved { color: var(--ok); }

.tb-group { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.tb-btn {
  background: var(--bg-elev); border: 1px solid var(--border);
  color: var(--text-dim); padding: 6px 10px; border-radius: 7px;
  cursor: pointer; font-size: 12.5px; font-family: var(--sans);
}
.tb-btn:hover { color: var(--text); border-color: var(--accent); background: var(--accent-bg); }
.tb-sep { width: 1px; height: 20px; background: var(--border); margin: 0 4px; }

/* Mermaid 图表类型下拉 */
.tb-dropdown { position: relative; display: inline-block; }
.tb-menu {
  position: absolute; top: calc(100% + 6px); left: 0; z-index: 50;
  min-width: 200px; padding: 6px; display: flex; flex-direction: column; gap: 2px;
  background: var(--bg-elev); border: 1px solid var(--border); border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.45);
}
.tb-menu[hidden] { display: none; }
.tb-menu-item {
  display: flex; flex-direction: column; align-items: flex-start; gap: 2px;
  background: transparent; border: none; border-radius: 7px; cursor: pointer;
  padding: 8px 10px; text-align: left; font-family: var(--sans);
}
.tb-menu-item:hover { background: var(--accent-bg); }
.tb-menu-label { color: var(--text); font-size: 13px; font-weight: 600; }
.tb-menu-hint { color: var(--text-dim); font-size: 11px; font-family: var(--mono); }

.editor-area { flex: 1; display: flex; min-height: 0; }
.app.view-edit .preview-pane { display: none; }
.app.view-preview .editor-pane { display: none; }

.pane { flex: 1; min-width: 0; overflow: hidden; display: flex; flex-direction: column; }
.editor-pane { border-right: 1px solid var(--border); }
.app.view-preview .editor-pane { border-right: none; }

.editor {
  flex: 1; width: 100%; min-height: 0; resize: none; border: none; outline: none;
  background: var(--bg-input); color: var(--text);
  font-family: var(--mono); font-size: 13.5px; line-height: 1.7;
  padding: 20px 22px; tab-size: 2;
}
.preview-pane { background: var(--bg); overflow: auto; }
.preview { padding: 22px 28px; max-width: 860px; }

.empty-state {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  background: var(--bg);
}
.app.has-doc .empty-state { display: none; }
.empty-card { text-align: center; max-width: 460px; padding: 30px; }
.empty-card h2 { margin: 14px 0 6px; }
.empty-card p { color: var(--text-dim); margin: 0 0 18px; }
.empty-feats { list-style: none; padding: 0; margin: 0 0 8px; text-align: left; display: inline-block; }
.empty-feats li { padding: 5px 0; color: var(--text-dim); }

/* ---------- Markdown preview ---------- */
.markdown-body { line-height: 1.7; color: var(--text); word-wrap: break-word; }
.markdown-body h1, .markdown-body h2, .markdown-body h3,
.markdown-body h4, .markdown-body h5, .markdown-body h6 {
  margin: 1.2em 0 0.5em; line-height: 1.3; font-weight: 700;
}
.markdown-body h1 { font-size: 1.8em; border-bottom: 1px solid var(--border); padding-bottom: 0.3em; }
.markdown-body h2 { font-size: 1.45em; border-bottom: 1px solid var(--border-soft); padding-bottom: 0.25em; }
.markdown-body h3 { font-size: 1.2em; }
.markdown-body p { margin: 0.7em 0; }
.markdown-body a { color: var(--accent-soft); text-decoration: none; }
.markdown-body a:hover { text-decoration: underline; }
.markdown-body img { max-width: 100%; border-radius: 8px; border: 1px solid var(--border); }
.markdown-body code {
  background: var(--bg-elev); padding: 2px 6px; border-radius: 5px;
  font-family: var(--mono); font-size: 0.9em; color: #ffd479;
}
.markdown-body pre {
  background: var(--bg-input); border: 1px solid var(--border);
  padding: 14px 16px; border-radius: 10px; overflow: auto;
}
.markdown-body pre code { background: none; padding: 0; color: var(--text); }
.markdown-body blockquote {
  margin: 0.8em 0; padding: 4px 16px; border-left: 3px solid var(--accent);
  color: var(--text-dim); background: var(--accent-bg); border-radius: 0 8px 8px 0;
}
.markdown-body table {
  border-collapse: collapse; width: 100%; margin: 0.9em 0; font-size: 13px;
}
.markdown-body th, .markdown-body td {
  border: 1px solid var(--border); padding: 8px 12px; text-align: left;
}
.markdown-body th { background: var(--bg-elev); font-weight: 600; }
.markdown-body tr:nth-child(even) td { background: var(--bg-soft); }
.markdown-body ul, .markdown-body ol { padding-left: 1.6em; margin: 0.6em 0; }
.markdown-body li { margin: 0.25em 0; }
.markdown-body hr { border: none; border-top: 1px solid var(--border); margin: 1.4em 0; }
.mermaid-block { background: var(--bg-soft); border: 1px solid var(--border); border-radius: 10px; padding: 16px; margin: 1em 0; text-align: center; overflow: auto; }
.mermaid-error { color: var(--danger); font-family: var(--mono); font-size: 12px; white-space: pre-wrap; }

/* scrollbars */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 6px; }
::-webkit-scrollbar-thumb:hover { background: #353c4f; }
::-webkit-scrollbar-track { background: transparent; }

@media (max-width: 720px) {
  .sidebar { position: absolute; z-index: 20; height: 100%; box-shadow: var(--shadow); }
  .app.sidebar-collapsed .sidebar { margin-left: -280px; }
}