:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --border: #e5e7eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(180deg, #eef4ff 0%, var(--bg) 40%);
  color: var(--text);
}

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 32px 20px 48px;
}

header h1 {
  margin: 0 0 8px;
  font-size: 28px;
}

header p {
  margin: 0 0 24px;
  color: var(--muted);
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
  margin-bottom: 20px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

label {
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 14px;
  font-weight: 600;
}

label.full {
  margin-top: 16px;
}

small {
  font-weight: 400;
  color: var(--muted);
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 14px;
  font-weight: 400;
  font-family: inherit;
  background: #fff;
}

textarea {
  resize: vertical;
}

.actions {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  margin-top: 20px;
}

button {
  border: none;
  border-radius: 10px;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  background: var(--primary);
  color: #fff;
}

button.secondary {
  background: #e5e7eb;
  color: #111827;
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}

.tab {
  background: #fff;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 10px 16px;
  font-size: 13px;
}

.tab.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.tab-panel {
  display: none;
}

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

.placeholder {
  text-align: center;
  padding: 64px 24px;
}

.placeholder h2 {
  margin: 0 0 12px;
  font-size: 20px;
}

.placeholder p {
  margin: 0;
  color: var(--muted);
}

#gpsPayload {
  font-family: Consolas, "Courier New", monospace;
  min-height: 360px;
  line-height: 1.5;
}

pre {
  margin: 0;
  background: #0f172a;
  color: #e2e8f0;
  border-radius: 12px;
  padding: 16px;
  overflow: auto;
  min-height: 180px;
  font-size: 13px;
  line-height: 1.5;
}

@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }
}