:root { color-scheme: light dark; }
* { box-sizing: border-box; }
body {
  margin: 0; min-height: 100vh; display: grid; place-items: center;
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: #0b1f2a; color: #e8eef2;
  -webkit-font-smoothing: antialiased;
}
main { text-align: center; padding: 2rem; max-width: 40rem; }
.mark {
  width: 72px; height: 72px; margin: 0 auto 1.5rem; border-radius: 18px;
  background: #0e7c86; display: grid; place-items: center;
  font-weight: 700; font-size: 40px; color: #fff;
  box-shadow: 0 8px 30px rgba(14, 124, 134, .4);
}
h1 { font-size: clamp(2rem, 6vw, 3rem); margin: 0 0 .5rem; letter-spacing: -.02em; }
p { color: #9fb3bd; margin: .25rem 0; }
.tag { color: #6f8a96; font-size: .85rem; margin-top: 2rem; }