:root { color-scheme: light dark; }
body {
  margin: 0; min-height: 100vh;
  display: flex; align-items: center; justify-content: center;
  background: #f6f7f9; color: #1b1f24;
  font-family: system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif;
}
.box { max-width: 34rem; padding: 2.5rem 1.5rem; text-align: center; }
.brand { letter-spacing: .3em; font-weight: 700; color: #5b6472; margin: 0 0 1.5rem; }
h1 { font-size: 1.35rem; line-height: 1.6; margin: 0 0 1rem; }
.lead { color: #4a5361; line-height: 1.9; margin: .3rem 0; }
a { color: #1a5fb4; }
@media (prefers-color-scheme: dark) {
  body { background: #14171c; color: #e6e9ee; }
  .brand, .lead { color: #a7b0be; }
  a { color: #7db1ff; }
}