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

:root {
  --color-bg: #F5F5F5;
  --color-surface: #ffffff;
  --color-text: #0D0D0D;
  --color-text-secondary: #666666;
  --color-text-tertiary: #AAAAAA;
  --color-accent: #0D0D0D;
  --color-border: #E0E0E0;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --radius: 10px;
  --max-width: 680px;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font);
  line-height: 1.7;
  padding: 0 20px 60px;
}

/* Header */
header {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 0 32px;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 40px;
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 14px;
}

.app-icon {
  width: 48px;
  height: 48px;
  border-radius: 11px;
  background: var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.app-icon svg {
  width: 26px;
  height: 26px;
  fill: #fff;
}

.brand h1 {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-text);
}

.brand p {
  font-size: 0.82rem;
  color: var(--color-text-tertiary);
}

/* Main content */
main {
  max-width: var(--max-width);
  margin: 0 auto;
}

.page-title {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-bottom: 8px;
}

.last-updated {
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
  margin-bottom: 36px;
}

/* Sections */
section {
  margin-bottom: 32px;
}

h2 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 10px;
  margin-top: 36px;
}

section:first-of-type h2 {
  margin-top: 0;
}

p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: 10px;
}

p:last-child {
  margin-bottom: 0;
}

ul, ol {
  padding-left: 20px;
  margin-bottom: 10px;
}

li {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: 5px;
}

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

a:hover {
  text-decoration: underline;
}

/* Info box */
.info-box {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin-bottom: 10px;
}

.info-box p {
  margin-bottom: 0;
}

/* Back link */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
  margin-bottom: 28px;
  text-decoration: none;
}

.back-link:hover {
  color: var(--color-accent);
  text-decoration: none;
}

/* Footer */
footer {
  max-width: var(--max-width);
  margin: 48px auto 0;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

footer p {
  font-size: 0.8rem;
  color: var(--color-text-tertiary);
  margin: 0;
}

footer a {
  color: var(--color-text-tertiary);
}

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

/* Index page cards */
.card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 32px;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px 20px;
  text-decoration: none;
  display: block;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
  text-decoration: none;
}

.card-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-accent);
  margin-bottom: 6px;
}

.card h2 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 6px;
}

.card p {
  font-size: 0.83rem;
  color: var(--color-text-tertiary);
  margin: 0;
}

/* Responsive */
@media (max-width: 480px) {
  .card-grid {
    grid-template-columns: 1fr;
  }

  .page-title {
    font-size: 1.45rem;
  }
}