:root {
  --bg: #0a0e14;
  --bg-card: #12181f;
  --bg-input: #0d1319;
  --border: #1f2a35;
  --text: #e6edf3;
  --text-dim: #8b98a5;
  --neon: #4fd1ff;
  --neon-dim: rgba(79, 209, 255, 0.35);
  --danger: #ff6b6b;
  --danger-dim: rgba(255, 107, 107, 0.12);

  --json-key: #4fd1ff;
  --json-string: #9ad68f;
  --json-number: #ffcb6b;
  --json-boolean: #c792ea;
  --json-null: #6b7785;
  --json-punct: #56646f;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background:
    radial-gradient(circle at 50% 0%, rgba(79, 209, 255, 0.1), transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

header {
  padding: 28px 24px 16px;
  text-align: center;
}

header h1 {
  font-family: "JetBrains Mono", "Courier New", monospace;
  font-size: 22px;
  font-weight: 600;
  margin: 0 0 6px;
  letter-spacing: 0.3px;
}

header h1 a {
  color: var(--text-dim);
  text-decoration: none;
}

header h1 a:hover {
  color: var(--text);
}

.accent {
  color: var(--neon);
}

.tagline {
  margin: 0;
  color: var(--text-dim);
  font-size: 13px;
}

main {
  flex: 1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  padding: 8px 24px 24px;
  max-width: 1400px;
  width: 100%;
  margin: 0 auto;
  min-height: 0;
}

@media (max-width: 900px) {
  main {
    grid-template-columns: 1fr;
  }
}

.panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  min-height: 420px;
  overflow: hidden;
}

.panel-toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.spacer {
  flex: 1;
}

.btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 12px;
  font-family: inherit;
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.btn:hover:not(:disabled) {
  border-color: var(--neon);
  color: var(--neon);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

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

.btn-accent:hover:not(:disabled) {
  border-color: var(--neon);
  box-shadow: 0 0 12px var(--neon-dim);
}

.input-area {
  flex: 1;
  resize: none;
  border: none;
  outline: none;
  background: var(--bg-input);
  color: var(--text);
  font-family: "JetBrains Mono", "Courier New", monospace;
  font-size: 13px;
  line-height: 1.5;
  padding: 14px;
  tab-size: 2;
}

.input-area::placeholder {
  color: var(--text-dim);
}

.input-panel.dragover .input-area {
  outline: 2px dashed var(--neon);
  outline-offset: -6px;
}

.error {
  padding: 10px 14px;
  background: var(--danger-dim);
  color: var(--danger);
  font-size: 12px;
  font-family: "JetBrains Mono", "Courier New", monospace;
  border-top: 1px solid var(--border);
  white-space: pre-wrap;
}

.error.hidden {
  display: none;
}

.meta {
  font-size: 12px;
  color: var(--text-dim);
  font-family: "JetBrains Mono", "Courier New", monospace;
}

.tree {
  flex: 1;
  overflow: auto;
  padding: 14px;
  font-family: "JetBrains Mono", "Courier New", monospace;
  font-size: 13px;
  line-height: 1.65;
}

.placeholder {
  color: var(--text-dim);
  margin: 0;
}

/* --- JSON tree --- */

.node {
  position: relative;
}

.node-line {
  display: flex;
  align-items: flex-start;
  white-space: pre;
}

.toggle {
  width: 16px;
  height: 20px;
  flex: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-dim);
  user-select: none;
  border-radius: 3px;
}

.toggle:hover {
  color: var(--neon);
  background: rgba(79, 209, 255, 0.08);
}

.toggle-spacer {
  width: 16px;
  flex: none;
}

.key {
  color: var(--json-key);
}

.punct {
  color: var(--json-punct);
}

.value-string { color: var(--json-string); }
.value-number { color: var(--json-number); }
.value-boolean { color: var(--json-boolean); }
.value-null { color: var(--json-null); }

.count {
  color: var(--text-dim);
  font-style: italic;
}

.children {
  margin-left: 16px;
  border-left: 1px solid var(--border);
  padding-left: 4px;
}

.node.collapsed > .children {
  display: none;
}

.node.collapsed > .node-line .ellipsis {
  display: inline;
}

.ellipsis {
  display: none;
  color: var(--text-dim);
}

footer {
  text-align: center;
  padding: 16px;
  color: var(--text-dim);
  font-size: 12px;
}

footer a {
  color: var(--neon);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}