:root {
  --paper: #eef3f7;
  --panel: #fbfcfd;
  --ink: #1a2740;
  --muted: #5b6a82;
  --line: #c5d0dc;
  --red: #c8102e;
  --blue: #0b3a82;
  --link: #0b3a82;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  min-height: 100vh;
  color: var(--ink);
  background:
    repeating-linear-gradient(
      135deg,
      var(--red) 0 10px,
      var(--paper) 10px 14px,
      var(--blue) 14px 24px,
      var(--paper) 24px 28px
    );
  font-family: "Iowan Old Style", "Palatino Linotype", Palatino, "Songti SC", "Noto Serif SC", "Times New Roman", serif;
  line-height: 1.65;
}

.sheet {
  max-width: 760px;
  margin: 28px auto;
  background: var(--panel);
  padding: 40px 44px 48px;
  border: 1px solid var(--line);
  box-shadow: 0 18px 40px rgba(16, 32, 64, 0.12);
}

header {
  border-bottom: 1px solid var(--line);
  padding-bottom: 18px;
  margin-bottom: 28px;
}
.mark {
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--blue);
}
h1 {
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 600;
  line-height: 1.2;
  margin: 10px 0 8px;
  text-wrap: pretty;
}
.lede {
  color: var(--muted);
  margin: 0;
  max-width: 42em;
}

nav {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  margin-top: 16px;
}
nav a, main a {
  color: var(--link);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
nav a:hover, main a:hover { color: var(--red); }

h2 {
  font-size: 1.15rem;
  margin: 1.8em 0 0.5em;
}
p, li { max-width: 42em; text-wrap: pretty; }
ul { padding-left: 1.2em; }
.meta {
  margin-top: 2.4em;
  padding-top: 1em;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}
footer {
  margin-top: 32px;
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 640px) {
  .sheet { margin: 0; padding: 28px 22px 36px; border: 0; box-shadow: none; }
}