* {
  box-sizing: border-box;
}

:root {
  --bg: #f5f6f8;
  --panel-bg: #ffffff;
  --border: #d8dce1;
  --text: #1f2430;
  --muted: #6b7280;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --error: #dc2626;
  --success: #16a34a;
}

html, body {
  height: 100%;
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.topbar {
  padding: 14px 20px;
  background: var(--panel-bg);
  border-bottom: 1px solid var(--border);
}

.topbar h1 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}

.app {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 53px);
  padding: 16px 20px;
  gap: 12px;
}

.toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.toolbar-sep {
  width: 1px;
  height: 24px;
  background: var(--border);
  margin: 0 4px;
}

.btn {
  padding: 7px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--panel-bg);
  color: var(--text);
  cursor: pointer;
  font-size: 13px;
  font-weight: 500;
}

.btn:hover {
  background: #eef1f5;
}

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

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-ghost {
  border-color: transparent;
  background: transparent;
  color: var(--muted);
}

.btn-ghost:hover {
  background: #eef1f5;
}

.select-label, .indent-label {
  font-size: 13px;
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 6px;
}

select {
  padding: 6px 8px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 13px;
  background: var(--panel-bg);
  color: var(--text);
}

.status-bar {
  min-height: 20px;
  font-size: 13px;
  padding: 0 2px;
}

.status-bar.error {
  color: var(--error);
}

.status-bar.success {
  color: var(--success);
}

.panes {
  flex: 1;
  display: flex;
  gap: 12px;
  min-height: 0;
}

.pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  position: relative;
  min-width: 0;
}

.pane-header {
  padding: 8px 12px;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
  background: #fafbfc;
}

.pane .CodeMirror {
  flex: 1;
  height: 100%;
  font-size: 13px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

.tree-view {
  flex: 1;
  overflow: auto;
  padding: 10px 14px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 13px;
}

.tree-view.hidden {
  display: none;
}

.tree-node {
  margin-left: 18px;
}

.tree-node.root {
  margin-left: 0;
}

.tree-line {
  display: flex;
  align-items: flex-start;
  gap: 4px;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
}

.tree-toggle {
  cursor: pointer;
  user-select: none;
  color: var(--muted);
  width: 14px;
  flex-shrink: 0;
  display: inline-block;
  text-align: center;
}

.tree-toggle.leaf {
  cursor: default;
  visibility: hidden;
}

.tree-key {
  color: #9333ea;
}

.tree-string {
  color: #16a34a;
}

.tree-number {
  color: #2563eb;
}

.tree-boolean {
  color: #ea580c;
}

.tree-null {
  color: var(--muted);
  font-style: italic;
}

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

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

.tree-count {
  color: var(--muted);
  font-size: 12px;
}

@media (max-width: 800px) {
  .panes {
    flex-direction: column;
  }
}