body {
  font-family: system-ui, sans-serif;
  margin: 0;
  padding: 0;
  max-width: 640px;
  margin-inline: auto;
  color: #222;
}
header { padding: 1rem; border-bottom: 1px solid #eee; }
header a { text-decoration: none; color: inherit; }
header nav a { margin-right: 1rem; }
main { padding: 1rem; }
.logo { max-width: 160px; }
.error { color: #b00020; }
table { border-collapse: collapse; width: 100%; }
td, th { border: 1px solid #ddd; padding: 0.5rem; text-align: left; }
.group-row { display: flex; gap: 0.5rem; align-items: center; margin-bottom: 0.5rem; }
form label { display: block; margin-bottom: 0.5rem; }