:root {
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-main: #0f172a;
  --text-muted: #475569;
  --border-color: #e2e8f0;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --accent-bg: #f1f5f9;
  --radius: 8px;
  --max-width: 780px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.65;
  color: var(--text-main);
  background-color: var(--bg-color);
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.site-header {
  border-bottom: 1px solid var(--border-color);
  background-color: var(--card-bg);
  padding: 1rem 0;
  margin-bottom: 2rem;
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 0.5rem;
}

.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-main);
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 1.25rem;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
}

.main-content {
  max-width: var(--max-width);
  margin: 0 auto;
  width: 100%;
  flex: 1;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 2.5rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

h1 {
  font-size: 1.85rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}

.subtitle {
  font-size: 1.05rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.25rem;
}

h2 {
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--text-main);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

p {
  margin-bottom: 1rem;
  color: var(--text-muted);
}

ul, ol {
  margin-bottom: 1.25rem;
  padding-left: 1.5rem;
  color: var(--text-muted);
}

li {
  margin-bottom: 0.5rem;
}

strong {
  color: var(--text-main);
}

.notice-box {
  background-color: var(--accent-bg);
  border-left: 4px solid var(--primary);
  padding: 1rem 1.25rem;
  border-radius: 4px;
  margin: 1.5rem 0;
}

.notice-box p:last-child {
  margin-bottom: 0;
}

.action-links {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 0.6rem 1.2rem;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: 6px;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

.btn-secondary {
  background-color: #ffffff;
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--accent-bg);
}

.site-footer {
  max-width: var(--max-width);
  margin: 3rem auto 2rem;
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-muted);
  width: 100%;
}

.site-footer a {
  color: var(--text-muted);
  text-decoration: underline;
}

.site-footer a:hover {
  color: var(--primary);
}

.footer-nav {
  margin-bottom: 0.75rem;
  display: flex;
  justify-content: center;
  gap: 1.5rem;
}

@media (max-width: 640px) {
  .main-content {
    padding: 1.5rem;
  }
  .nav-container {
    flex-direction: column;
    gap: 0.75rem;
  }
  h1 {
    font-size: 1.5rem;
  }
}