* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: #f7f9fc;
  color: #333;
}

header {
  text-align: center;
  background: linear-gradient(90deg, #007bff, #00d4ff);
  color: white;
  padding: 1.5rem 1rem;
}

h1 {
  margin-top: 0.2rem;
}

.container {
  display: flex;
  flex-direction: row;
  height: calc(100vh - 160px);
  padding: 1rem;
  gap: 1rem;
}

.editor-pane,
.preview-pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

label {
  font-weight: bold;
  color: #007bff;
}

textarea {
  height: 150px;
  width: 100%;
  padding: 10px;
  font-family: monospace;
  font-size: 0.9rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  background: #ffffff;
  resize: vertical;
}

iframe {
  flex: 1;
  width: 100%;
  border: 1px solid #ccc;
  border-radius: 6px;
  background: white;
}

button {
  padding: 0.5rem 1rem;
  background-color: #007bff;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background-color: #0056b3;
}

.dom-toggle {
  margin-top: 1rem;
  font-size: 0.9rem;
}

.dom-toggle input {
  margin-right: 0.5rem;
}

.dom-pane {
  background: #ffffff;
  border: 1px solid #ddd;
  border-radius: 6px;
  padding: 1rem;
  max-height: 250px;
  overflow-y: auto;
  margin-top: 0.5rem;
}

.dom-tree {
  font-family: monospace;
  font-size: 0.85rem;
  color: #333;
  white-space: pre;
}

.dom-node {
  margin: 0.2rem 0;
  cursor: pointer;
  transition: background 0.2s;
  user-select: none;
}

.dom-node:hover {
  background: #e6f7ff;
  color: #007bff;
}

.dom-node.copied {
  background: #c6f6d5;
  color: #2f855a;
}

.tip {
  font-size: 0.75rem;
  color: #777;
  margin-top: 0.5rem;
}