:root {
  --bg: #0f1419;
  --panel: #161b22;
  --border: #30363d;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #3fb950;
  --accent-dim: #238636;
  --danger: #f85149;
  --danger-dim: #da3633;
  --focus: #58a6ff;
  --mono: "JetBrains Mono", "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  --sans: "IBM Plex Sans", "PingFang SC", "Noto Sans SC", system-ui, sans-serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
}

.app {
  display: grid;
  grid-template-columns: minmax(240px, 300px) 1fr;
  height: 100vh;
}

.sidebar {
  display: flex;
  flex-direction: column;
  border-right: 1px solid var(--border);
  background: var(--panel);
  min-height: 0;
}

.sidebar-head {
  padding: 1rem 1rem 0.5rem;
}

.brand {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.85rem;
}

.brand:hover { color: var(--text); }

.sidebar-head h1 {
  margin: 0.4rem 0 0.2rem;
  font-size: 1.25rem;
  font-weight: 600;
}

.hint {
  margin: 0;
  font-size: 0.75rem;
  color: var(--muted);
}

.hint.ok { color: var(--accent); }
.hint.err { color: var(--danger); }

.toolbar {
  display: flex;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
}

.filter {
  margin: 0 1rem 0.75rem;
  padding: 0.45rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  color: var(--text);
  font-size: 0.85rem;
}

.file-list {
  flex: 1;
  overflow: auto;
  padding: 0 0.5rem 1rem;
}

.file-item {
  display: block;
  width: 100%;
  text-align: left;
  border: none;
  background: transparent;
  color: var(--text);
  padding: 0.45rem 0.6rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--mono);
  font-size: 0.72rem;
  line-height: 1.35;
  word-break: break-all;
}

.file-item:hover { background: rgba(88, 166, 255, 0.08); }
.file-item.active { background: rgba(63, 185, 80, 0.15); color: var(--accent); }

.main {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
}

.editor-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
  flex-wrap: wrap;
}

.path-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
}

.label {
  color: var(--muted);
  font-size: 0.8rem;
}

.path {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--focus);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.actions { display: flex; gap: 0.5rem; }

.btn {
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  border-radius: 6px;
  padding: 0.4rem 0.75rem;
  font-size: 0.85rem;
  cursor: pointer;
}

.btn:hover:not(:disabled) { border-color: var(--muted); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.btn.primary {
  background: var(--accent-dim);
  border-color: var(--accent);
}

.btn.danger {
  border-color: var(--danger-dim);
  color: var(--danger);
}

.panes {
  flex: 1;
  display: grid;
  grid-template-columns: 1fr;
  min-height: 0;
}

.panes.split {
  grid-template-columns: 1fr 1fr;
}

.editor {
  width: 100%;
  height: 100%;
  border: none;
  resize: none;
  padding: 1rem 1.25rem;
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.9rem;
  line-height: 1.55;
  outline: none;
}

.editor.drag-over {
  outline: 2px dashed var(--accent);
  outline-offset: -8px;
  background: rgba(63, 185, 80, 0.06);
}

.preview {
  overflow: auto;
  padding: 1rem 1.5rem 2rem;
  border-left: 1px solid var(--border);
  background: #0d1117;
  line-height: 1.65;
}

.preview.hidden { display: none; }

.preview h1, .preview h2, .preview h3 { margin-top: 1.2em; }
.preview pre.code-block {
  position: relative;
  background: #23241f;
  padding: 1.75rem 1rem 0.85rem;
  border-radius: 8px;
  overflow: auto;
  border: 1px solid #3a3a32;
}
.preview pre.code-block code {
  background: transparent;
  padding: 0;
  display: block;
  overflow-x: auto;
}
.preview .lang-badge {
  position: absolute;
  top: 0.4rem;
  right: 0.55rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  color: #a6e22e;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid #4a4a40;
  border-radius: 4px;
  padding: 0.1rem 0.4rem;
  text-transform: lowercase;
  letter-spacing: 0.02em;
}
.preview :not(pre) > code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: rgba(110, 118, 129, 0.25);
  padding: 0.15em 0.35em;
  border-radius: 4px;
}
.preview a { color: var(--focus); }

.preview img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  display: block;
  margin: 0.75rem 0;
  border: 1px solid var(--border);
  background: #fff;
}

.preview .img-error {
  color: var(--danger);
  font-size: 0.85rem;
  padding: 0.5rem 0.75rem;
  border: 1px dashed var(--danger);
  border-radius: 6px;
  background: rgba(248, 81, 73, 0.08);
}

.preview .preview-empty {
  color: var(--muted);
  font-style: italic;
}

.preview .pdf-embed {
  margin: 1rem 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: #0d1117;
}

.preview .pdf-embed__bar {
  padding: 0.45rem 0.75rem;
  border-bottom: 1px solid var(--border);
  background: #161b22;
  font-size: 0.85rem;
}

.preview .pdf-embed__frame {
  display: block;
  width: 100%;
  min-height: 420px;
  border: 0;
  background: #111;
}

.status-bar {
  display: flex;
  justify-content: space-between;
  padding: 0.4rem 1rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.75rem;
  background: var(--panel);
}

dialog {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--panel);
  color: var(--text);
  padding: 1.25rem;
  width: min(420px, 92vw);
}

dialog::backdrop { background: rgba(0, 0, 0, 0.55); }

dialog h2 { margin: 0 0 1rem; font-size: 1.1rem; }

dialog label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 0.85rem;
  font-size: 0.85rem;
  color: var(--muted);
}

dialog input, dialog select {
  padding: 0.5rem 0.6rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-size: 0.9rem;
}

.dialog-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: flex-end;
  margin-top: 0.5rem;
}

@media (max-width: 860px) {
  .app { grid-template-columns: 1fr; grid-template-rows: 40vh 1fr; }
  .panes.split { grid-template-columns: 1fr; }
  .preview { border-left: none; border-top: 1px solid var(--border); max-height: 40vh; }
}