:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --text: #1e2430;
  --muted: #5d6678;
  --accent: #0b63ce;
  --border: #d9deea;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Avenir Next", "Segoe UI", sans-serif;
  color: var(--text);
  background: radial-gradient(circle at top right, #e6eefb, var(--bg) 45%);
  line-height: 1.55;
}

.container {
  width: min(980px, 92%);
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: #fff;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.15rem 0;
}

nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 0.9rem;
  font-weight: 600;
}

nav a:hover { color: var(--accent); }

main {
  padding: 1.2rem 0 2rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.85rem;
  padding: 1rem 1.1rem;
  margin: 0 0 1rem;
}

h1 { margin: 0; font-size: clamp(1.3rem, 2.5vw, 1.8rem); }
h2 { margin: 0 0 0.7rem; font-size: 1.15rem; }
h3 { margin: 1rem 0 0.35rem; font-size: 1rem; }

.small { font-size: 0.9rem; }
.muted { color: var(--muted); }
.hint { color: #8a541a; }
a { color: var(--accent); }

.site-footer {
  border-top: 1px solid var(--border);
  background: #fff;
}

.footer-inner {
  padding: 1rem 0;
}

@media (max-width: 760px) {
  .header-inner { flex-direction: column; align-items: flex-start; }
  nav a { margin-left: 0; margin-right: 0.9rem; }
}