:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --border: #e5e7eb;
  --shadow: 0 10px 30px rgba(17, 24, 39, 0.08);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  margin: 0;
  font-family: "Inter", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  background: var(--bg);
  color: var(--text);
}

a {
  color: var(--primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

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

.header-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-weight: 700;
  letter-spacing: 0.2px;
  color: var(--text);
}

.nav-links {
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--muted);
}

.nav-links a.active {
  color: var(--primary);
  font-weight: 600;
}

.page-wrap {
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 2.5rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 1.5rem;
}

h1 {
  margin-top: 0;
  margin-bottom: 0.25rem;
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  line-height: 1.2;
}

h2 {
  margin-top: 1.6rem;
  margin-bottom: 0.5rem;
  font-size: clamp(1.1rem, 2.8vw, 1.35rem);
}

p {
  margin-top: 0.6rem;
  margin-bottom: 0.7rem;
}

.meta {
  margin-top: 0.3rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.notice {
  margin-top: 1rem;
  padding: 0.85rem 1rem;
  border: 1px solid #c7d2fe;
  background: #eef2ff;
  color: #312e81;
  border-radius: 10px;
  font-weight: 500;
}

ul,
ol {
  margin-top: 0.5rem;
  margin-bottom: 1rem;
  padding-left: 1.25rem;
}

li + li {
  margin-top: 0.45rem;
}

.button {
  display: inline-block;
  margin-top: 0.6rem;
  border: 0;
  border-radius: 10px;
  padding: 0.8rem 1.1rem;
  font-size: 1rem;
  font-weight: 600;
  background: var(--primary);
  color: #ffffff;
  cursor: pointer;
  transition: background 0.2s ease;
}

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

.button:focus-visible {
  outline: 3px solid #93c5fd;
  outline-offset: 2px;
}

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

.footer-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 1rem 1.25rem;
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 520px) {
  .header-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}