:root {
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-accent: #22c55e;
  --color-bg: #f8fafc;
  --color-card: #ffffff;
  --color-text: #0f172a;
  --color-muted: #5b6476;
  --color-border: #e7edf4;
  --radius: 12px;
  --container: 1120px;
  --shadow-sm: 0 6px 18px rgba(15, 23, 42, 0.06);
  --shadow-hover: 0 10px 26px rgba(15, 23, 42, 0.09);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", system-ui, -apple-system, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  letter-spacing: -0.01em;
}

a {
  color: inherit;
  text-decoration: none;
}

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

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 20px 24px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(248, 250, 252, 0.92);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-border);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.08rem;
  letter-spacing: -0.02em;
}

.logo-mark {
  width: 14px;
  height: 14px;
  border-radius: 4px;
  background: var(--color-primary);
  display: inline-block;
}

.nav {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.nav a {
  font-weight: 500;
  color: var(--color-muted);
}

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

.nav-toggle {
  display: none;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 8px 12px;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  background: #ffffff;
  color: var(--color-text);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}

main {
  padding: 16px 0 64px;
}

.hero {
  margin: 8px 0 32px;
}

.hero h1 {
  font-size: clamp(1.75rem, 2vw + 1.2rem, 2.35rem);
  margin: 0 0 8px;
  line-height: 1.2;
}

.hero p {
  margin: 0;
  color: var(--color-muted);
  max-width: 60ch;
}

.section {
  margin: 32px 0;
}

.section-header {
  display: grid;
  gap: 6px;
  margin-bottom: 16px;
}

.section-header h2 {
  margin: 0;
  font-size: 1.25rem;
}

.section-header p {
  margin: 0;
  color: var(--color-muted);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 18px;
}

.reading {
  max-width: 70ch;
}

.article-body {
  margin: 24px 0;
}

.article-body p {
  margin: 0 0 16px;
}

.article-body h2,
.article-body h3 {
  margin-top: 28px;
}

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 24px 0 32px;
  background: #ffffff;
}

.footer-links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.footer-links a {
  color: var(--color-muted);
  font-weight: 500;
}

@media (max-width: 720px) {
  .container {
    padding: 14px 16px;
  }

  .site-header__inner {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 10px 12px;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav {
    display: none;
    grid-column: 1 / -1;
    width: 100%;
    gap: 0;
    padding-top: 4px;
    border-top: 1px solid var(--color-border);
  }

  .nav.is-open {
    display: grid;
  }

  .nav a {
    min-height: 44px;
    display: flex;
    align-items: center;
    padding: 6px 2px;
    border-bottom: 1px solid var(--color-border);
  }

  .nav a:last-child {
    border-bottom: 0;
  }

  main {
    padding-top: 8px;
  }

  .hero {
    margin-bottom: 20px;
  }

  .hero h1 {
    font-size: 1.75rem;
  }
}