:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --border: #e2e8f0;
  --blue: #2563eb;
  --blue-dark: #1d4ed8;
  --soft: #eff6ff;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
}

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

img {
  display: block;
  max-width: 100%;
}

.container {
  width: min(1120px, calc(100% - 28px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
}

.header-inner {
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-size: 22px;
  font-weight: 900;
}

.brand img {
  width: 58px;
  height: 58px;
  object-fit: contain;
}

.nav {
  display: flex;
  align-items: center;
  gap: 20px;
  color: #334155;
  font-weight: 750;
}

.nav a:hover,
.breadcrumbs a:hover,
.article a:not(.button):hover {
  color: var(--blue);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 13px 18px;
  border-radius: 14px;
  background: var(--blue);
  color: #fff;
  font-weight: 900;
}

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

.breadcrumbs {
  padding-top: 28px;
  color: #64748b;
  font-size: 14px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 0.8fr);
  gap: 34px;
  align-items: center;
  padding: 32px 0 38px;
}

.hero h1 {
  margin: 0 0 16px;
  font-size: clamp(38px, 6vw, 66px);
  line-height: 1.04;
  letter-spacing: -0.035em;
}

.hero p {
  margin: 0;
  max-width: 760px;
  color: var(--muted);
  font-size: 19px;
}

.hero img {
  width: 100%;
  height: auto;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: 0 18px 48px rgba(15, 23, 42, 0.12);
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 24px;
  align-items: start;
  padding-bottom: 38px;
}

.article,
.side-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.06);
}

.article {
  padding: clamp(22px, 5vw, 44px);
}

.article h2 {
  margin: 34px 0 12px;
  font-size: clamp(25px, 4vw, 34px);
  line-height: 1.2;
}

.article h2:first-child {
  margin-top: 0;
}

.article h3 {
  margin: 24px 0 8px;
  font-size: 21px;
}

.article p,
.article li {
  color: #334155;
}

.article ul,
.article ol {
  padding-left: 24px;
}

.article li + li {
  margin-top: 8px;
}

.article a:not(.button) {
  color: var(--blue-dark);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.note {
  margin: 24px 0;
  padding: 18px 20px;
  border-left: 4px solid var(--blue);
  border-radius: 12px;
  background: var(--soft);
  color: #1e3a8a;
}

.checklist {
  padding: 20px 22px;
  border: 1px solid #bfdbfe;
  border-radius: 18px;
  background: #f8fbff;
}

.side-card {
  position: sticky;
  top: 100px;
  padding: 22px;
}

.side-card h2 {
  margin: 0 0 10px;
  font-size: 23px;
}

.side-card p {
  color: var(--muted);
}

.side-card .button {
  width: 100%;
  margin-top: 8px;
}

.site-footer {
  padding: 28px 0 36px;
  border-top: 1px solid var(--border);
  color: #64748b;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  margin-top: 8px;
}

@media (max-width: 900px) {
  .nav {
    display: none;
  }

  .hero,
  .article-layout {
    grid-template-columns: 1fr;
  }

  .side-card {
    position: static;
  }
}

@media (max-width: 620px) {
  .header-inner {
    min-height: 68px;
  }

  .brand span {
    display: none;
  }

  .brand img {
    width: 52px;
    height: 52px;
  }

  .hero {
    padding-top: 24px;
  }
}