*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #f5f5f5;
  --panel-bg: #fff;
  --border: #ddd;
  --text: #333;
  --text-muted: #888;
  --accent: #4a90d9;
  --accent-hover: #357abd;
  --header-bg: #2c3e50;
  --header-text: #ecf0f1;
  --toolbar-bg: #eee;
  --error: #e74c3c;
  --success: #27ae60;
  --key-color: #881391;
  --string-color: #1a8f29;
  --number-color: #1a5fb4;
  --bool-color: #c45b00;
  --null-color: #888;
  --bracket-color: #555;
  --type-color: #999;
  --search-highlight: #fff3a8;
  --search-active: #ffc107;
  --tree-line: #ddd;
}

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 14px;
  color: var(--text);
  background: var(--bg);
}

body {
  display: flex;
  flex-direction: column;
}

header {
  background: var(--header-bg);
  color: var(--header-text);
  padding: 10px 20px;
  flex-shrink: 0;
}

header h1 {
  font-size: 18px;
  font-weight: 600;
}

.subtitle {
  font-size: 12px;
  opacity: 0.7;
  margin-top: 2px;
}

/* Toolbar */
.toolbar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  background: var(--toolbar-bg);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  flex-wrap: wrap;
}

.toolbar button {
  padding: 5px 14px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--panel-bg);
  color: var(--text);
  cursor: pointer;
  font-size: 13px;
  transition: background 0.15s, border-color 0.15s;
}

.toolbar button:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.toolbar button:active {
  background: var(--accent-hover);
}

.toolbar-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 12px;
}

.toolbar-right label {
  font-size: 12px;
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
}

.toolbar-right label input {
  margin-right: 4px;
  vertical-align: middle;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
}

.search-box input {
  padding: 4px 8px;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 12px;
  width: 180px;
  outline: none;
}

.search-box input:focus {
  border-color: var(--accent);
}

#search-count {
  font-size: 11px;
  color: var(--text-muted);
  margin-left: 6px;
  white-space: nowrap;
}

/* Main panels */
main {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.panel {
  display: flex;
  flex-direction: column;
  min-width: 200px;
}

.panel-input {
  flex: 1;
}

.panel-output {
  flex: 1;
  overflow: hidden;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 12px;
  background: var(--toolbar-bg);
  border-bottom: 1px solid var(--border);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  flex-shrink: 0;
}

.info {
  font-weight: 400;
  font-size: 11px;
  text-transform: none;
  letter-spacing: 0;
}

#json-input {
  flex: 1;
  width: 100%;
  border: none;
  padding: 12px;
  font-family: "SF Mono", "Fira Code", "Fira Mono", Menlo, Consolas, "DejaVu Sans Mono", monospace;
  font-size: 13px;
  line-height: 1.5;
  resize: none;
  outline: none;
  background: var(--panel-bg);
  color: var(--text);
  tab-size: 2;
}

/* Resizer */
.resizer {
  width: 5px;
  cursor: col-resize;
  background: var(--border);
  flex-shrink: 0;
  transition: background 0.15s;
}

.resizer:hover,
.resizer.active {
  background: var(--accent);
}

/* Tree output */
#tree-output {
  flex: 1;
  overflow: auto;
  padding: 12px;
  font-family: "SF Mono", "Fira Code", "Fira Mono", Menlo, Consolas, "DejaVu Sans Mono", monospace;
  font-size: 13px;
  line-height: 1.6;
  background: var(--panel-bg);
}

/* Tree nodes */
.tree-node {
  position: relative;
}

.tree-children {
  padding-left: 20px;
  border-left: 1px dashed var(--tree-line);
  margin-left: 4px;
}

.tree-line {
  display: flex;
  align-items: baseline;
  padding: 1px 0;
  cursor: default;
}

.tree-line:hover {
  background: rgba(74, 144, 217, 0.06);
}

.tree-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 16px;
  height: 16px;
  font-size: 10px;
  cursor: pointer;
  color: var(--text-muted);
  user-select: none;
  flex-shrink: 0;
  border-radius: 3px;
  margin-right: 2px;
}

.tree-toggle:hover {
  background: rgba(0,0,0,0.08);
}

.tree-key {
  color: var(--key-color);
  margin-right: 4px;
}

.tree-colon {
  color: var(--text-muted);
  margin-right: 6px;
}

.tree-value-string {
  color: var(--string-color);
}

.tree-value-number {
  color: var(--number-color);
}

.tree-value-boolean {
  color: var(--bool-color);
}

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

.tree-bracket {
  color: var(--bracket-color);
  font-weight: 500;
}

.tree-type {
  color: var(--type-color);
  font-size: 11px;
  margin-left: 8px;
  font-style: italic;
}

.tree-index {
  color: var(--type-color);
  font-size: 11px;
  margin-right: 4px;
}

.tree-summary {
  color: var(--text-muted);
  font-size: 12px;
  margin-left: 4px;
}

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

.collapsed > .tree-line.tree-close-line {
  display: none;
}

.tree-collapsed-preview {
  display: none;
  color: var(--text-muted);
  font-size: 12px;
}

.collapsed > .tree-line:first-child .tree-collapsed-preview {
  display: inline;
}

/* Search highlight */
.search-match {
  background: var(--search-highlight);
  border-radius: 2px;
  padding: 0 1px;
}

.search-match-active {
  background: var(--search-active);
}

/* Error display */
.error-message {
  color: var(--error);
  padding: 12px;
  white-space: pre-wrap;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
}

/* Status bar */
#status-bar {
  padding: 4px 12px;
  background: var(--toolbar-bg);
  border-top: 1px solid var(--border);
  font-size: 11px;
  color: var(--text-muted);
  flex-shrink: 0;
}

#status-bar.error {
  color: var(--error);
  background: #fde8e8;
}

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

/* Drag and drop */
#json-input.drag-over {
  background: #e8f0fe;
  border: 2px dashed var(--accent);
}

/* Responsive */
@media (max-width: 768px) {
  main {
    flex-direction: column;
  }
  .resizer {
    width: auto;
    height: 5px;
    cursor: row-resize;
  }
  .panel {
    min-width: auto;
    min-height: 150px;
  }
}