:root {
  --ink: #1a2233;
  --muted: #5f6b7a;
  --line: #dfe3e8;
  --paper: #f5f6f8;
  --card: #ffffff;
  --accent: #a3760a;
  --accent-deep: #7a5406;
  --navy: #1a2233;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

h1, h2, h3 { font-family: Georgia, "Times New Roman", serif; font-weight: normal; }

a { color: var(--accent-deep); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.wrap { max-width: 800px; margin: 0 auto; padding: 0 20px; }

header.top {
  background: var(--navy);
}

header.top .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  flex-wrap: wrap;
  gap: 10px;
}

.mark {
  font-family: Georgia, serif;
  font-size: 17px;
  color: #fff;
}

.mark .accent { color: #d4a736; }

nav.top ul {
  list-style: none;
  display: flex;
  gap: 20px;
  margin: 0;
  padding: 0;
  font-size: 13px;
}

nav.top a { color: #cfd6e0; }
nav.top a:hover { color: #fff; text-decoration: none; }

.intro { padding: 34px 0 24px; border-bottom: 1px solid var(--line); }

.intro h1 { font-size: 24px; margin: 0 0 10px; max-width: 32ch; }

.intro p { color: var(--muted); font-size: 14.5px; max-width: 58ch; }

.modules { padding: 26px 0 30px; }

.module {
  display: flex;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.module:last-child { border-bottom: none; }

.num {
  font-family: Georgia, serif;
  font-size: 22px;
  color: var(--accent);
  min-width: 34px;
}

.module h3 {
  font-size: 15.5px;
  margin: 0 0 5px;
  color: var(--ink);
}

.module p {
  margin: 0;
  font-size: 13.5px;
  color: var(--muted);
}

section.block {
  padding: 26px 0;
  border-top: 1px solid var(--line);
}

section.block h2 { font-size: 17px; margin: 0 0 12px; }

section.block p, section.block li { font-size: 14px; color: var(--muted); }

ul.plain { padding-left: 18px; margin: 6px 0; }
ul.plain li { margin-bottom: 4px; }

footer.bottom {
  padding: 22px 0 40px;
  font-size: 12.5px;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

footer.bottom .wrap {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

.error-block { padding: 80px 0; }
.error-block .code { font-family: Georgia, serif; font-size: 15px; color: var(--muted); margin-bottom: 8px; }
.error-block h1 { font-size: 22px; margin: 0 0 12px; }