:root {
  color-scheme: light dark;
  --navy: #0d233b;
  --blue: #59bde8;
  --gold: #f4b942;
  --paper: #ffffff;
  --ink: #132238;
  --muted: #526174;
  --line: #d9e2ec;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
  color: var(--ink);
  background: #f4f7fa;
}

header {
  color: white;
  background: linear-gradient(135deg, var(--navy), #174b70);
  padding: 2rem 1.25rem;
}

.brand, main, footer { max-width: 780px; margin: 0 auto; }
.brand { display: flex; align-items: center; gap: 1rem; }
.mark {
  width: 54px;
  height: 54px;
  display: grid;
  place-items: center;
  border-radius: 16px;
  color: var(--navy);
  background: var(--gold);
  font-size: 1.65rem;
}
h1 { margin: 0; font-size: clamp(1.7rem, 4vw, 2.35rem); line-height: 1.2; }
.subtitle { margin: .25rem 0 0; color: #d8edf8; }

main {
  margin-top: 1.5rem;
  margin-bottom: 2rem;
  padding: 1.5rem clamp(1.1rem, 4vw, 2.5rem) 2.5rem;
  border-radius: 18px;
  background: var(--paper);
  box-shadow: 0 14px 40px rgb(13 35 59 / 10%);
}

h2 { margin-top: 1.8rem; color: var(--navy); line-height: 1.3; }
a { color: #0b6e9d; }
.notice {
  padding: 1rem 1.15rem;
  border-left: 5px solid var(--blue);
  border-radius: 8px;
  background: #edf8fd;
}
.button {
  display: inline-block;
  margin: .4rem 0;
  padding: .75rem 1.1rem;
  border-radius: 999px;
  color: var(--navy);
  background: var(--blue);
  font-weight: 700;
  text-decoration: none;
}
footer { padding: 0 1.25rem 2rem; color: var(--muted); font-size: .95rem; }

@media (max-width: 820px) {
  main { margin: 0; border-radius: 0; box-shadow: none; }
}

@media (prefers-color-scheme: dark) {
  :root { --paper: #19232f; --ink: #eef4fa; --muted: #b9c7d5; --line: #384758; }
  body { background: #101820; }
  h2 { color: #9cdcf7; }
  a { color: #77cff4; }
  .notice { background: #162f3d; }
}