body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #f4f6f8;
}

header, footer {
  text-align: center;
  padding: 10px;
  background: #222;
  color: #fff;
}

main {
  max-width: 900px;
  margin: auto;
  padding: 10px;
}

.card {
  background: #fff;
  padding: 10px;
  margin-bottom: 10px;
  border-radius: 6px;
}

.row {
  display: flex;
  gap: 5px;
}

input, select, textarea, button {
  width: 100%;
  padding: 6px;
}

textarea {
  min-height: 80px;
}

button {
  cursor: pointer;
}

.tabs {
  display: flex;
  margin-top: 8px;
}

.tab {
  flex: 1;
  padding: 6px;
  border: none;
  background: #ddd;
}

.tab.active {
  background: #bbb;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

pre {
  background: #111;
  color: #0f0;
  padding: 10px;
  overflow: auto;
}

#history li {
  cursor: pointer;
  font-size: 0.9em;
}