:root {
  --blue: #2A75E6;
  --blue-dark: #1d5cc0;
  --blue-soft: #eef4fe;
  --text: #14171f;
  --muted: #5f6675;
  --line: #e7eaf0;
  --bg: #fafbfd;
  --card: #fff;
  --radius: 16px;
  --shadow: 0 1px 2px rgba(20,23,31,.04), 0 4px 16px rgba(20,23,31,.06);
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--text); background: var(--bg);
  font-size: 17px; line-height: 1.6;
}
a { color: var(--blue); }
img { max-width: 100%; height: auto; display: block; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }
.narrow { max-width: 720px; margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 10;
  background: rgba(255,255,255,.85);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.site-header .container { display: flex; align-items: center; gap: 24px; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 19px; color: var(--text); text-decoration: none; flex-shrink: 0; }
.logo img { width: 30px; height: 30px; border-radius: 8px; }
.nav { display: flex; gap: 4px; overflow-x: auto; scrollbar-width: none; }
.nav::-webkit-scrollbar { display: none; }
.nav a { white-space: nowrap; padding: 8px 12px; border-radius: 999px; color: var(--muted); text-decoration: none; font-size: 15px; font-weight: 500; }
.nav a:hover, .nav a.active { background: var(--blue-soft); color: var(--blue); }

/* Hero */
.hero { padding: 64px 0 24px; }
.hero h1 { font-size: clamp(34px, 5vw, 54px); line-height: 1.08; letter-spacing: -.025em; margin: 0 0 16px; max-width: 760px; }
.hero p { font-size: 19px; color: var(--muted); max-width: 620px; margin: 0; }
.section-title { font-size: 22px; letter-spacing: -.01em; margin: 48px 0 20px; }

/* Cards */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 24px; }
.card {
  background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow);
  overflow: hidden; display: flex; flex-direction: column;
  text-decoration: none; color: inherit; transition: transform .2s, box-shadow .2s;
}
.card:hover { transform: translateY(-3px); box-shadow: 0 2px 4px rgba(20,23,31,.05), 0 12px 32px rgba(20,23,31,.10); }
.card-img { aspect-ratio: 16 / 9; width: 100%; object-fit: cover; background: linear-gradient(135deg, #2A75E6, #7ab0f7); }
.card-body { padding: 18px 20px 22px; }
.card h3 { font-size: 19px; line-height: 1.35; letter-spacing: -.01em; margin: 12px 0 8px; }
.card p { margin: 0; color: var(--muted); font-size: 15px; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.tag { display: inline-block; font-size: 13px; font-weight: 600; color: var(--blue); background: var(--blue-soft); padding: 4px 10px; border-radius: 999px; text-decoration: none; }
.empty { color: var(--muted); }

/* Article */
.crumbs { font-size: 14px; color: var(--muted); margin: 32px 0 20px; }
.crumbs a { color: var(--muted); text-decoration: none; }
.crumbs a:hover { color: var(--blue); }
.article-head h1 { font-size: clamp(30px, 4.5vw, 44px); line-height: 1.15; letter-spacing: -.02em; margin: 14px 0 12px; }
.meta { font-size: 14px; color: var(--muted); margin: 0; }
.article-cover { aspect-ratio: 16 / 9; width: 100%; object-fit: cover; border-radius: var(--radius); margin: 28px 0 8px; }
.prose { font-size: 19px; line-height: 1.75; }
.prose h2 { font-size: 27px; line-height: 1.25; letter-spacing: -.01em; margin: 44px 0 12px; }
.prose h3 { font-size: 21px; line-height: 1.3; margin: 32px 0 8px; }
.prose p { margin: 0 0 20px; }
.prose ul, .prose ol { padding-left: 24px; margin: 0 0 20px; }
.prose li { margin-bottom: 8px; }
.prose blockquote { margin: 28px 0; padding: 16px 22px; border-left: 4px solid var(--blue); background: var(--blue-soft); border-radius: 0 12px 12px 0; }
.prose blockquote p:last-child { margin: 0; }
.prose a { text-underline-offset: 3px; }
.disclaimer { font-size: 14px; color: var(--muted); border-top: 1px solid var(--line); padding-top: 16px; margin-top: 32px; }

/* App banner */
.app-banner {
  display: flex; align-items: center; gap: 20px;
  background: linear-gradient(135deg, var(--blue), var(--blue-dark));
  color: #fff; border-radius: 20px; padding: 24px 28px; margin: 48px 0;
}
.app-banner img { width: 56px; height: 56px; border-radius: 14px; flex-shrink: 0; }
.app-banner h3 { margin: 0 0 4px; font-size: 20px; }
.app-banner p { margin: 0; opacity: .9; font-size: 15px; }
.app-banner .btn { margin-left: auto; flex-shrink: 0; background: #fff; color: var(--blue); font-weight: 600; padding: 12px 20px; border-radius: 12px; text-decoration: none; white-space: nowrap; }
.app-banner .btn:hover { background: var(--blue-soft); }

/* Pages */
.page-title { font-size: clamp(30px, 4.5vw, 40px); line-height: 1.15; letter-spacing: -.02em; margin: 48px 0 24px; }

/* Footer */
.site-footer { margin-top: 80px; border-top: 1px solid var(--line); background: #fff; padding: 32px 0; font-size: 14px; color: var(--muted); }
.site-footer .container { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 16px; }
.site-footer a { color: var(--muted); text-decoration: none; margin-right: 18px; }
.site-footer a:hover { color: var(--blue); }

@media (max-width: 600px) {
  body { font-size: 16px; }
  .hero { padding: 40px 0 8px; }
  .prose { font-size: 18px; }
  .app-banner { flex-direction: column; align-items: flex-start; }
  .app-banner .btn { margin-left: 0; }
}


/* Topics */
.topics { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.topic { display: flex; flex-direction: column; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; text-decoration: none; color: inherit; transition: border-color .2s, transform .2s; }
.topic:hover { border-color: var(--blue); transform: translateY(-2px); }
.topic h3 { margin: 0 0 6px; font-size: 18px; }
.topic p { margin: 0 0 14px; color: var(--muted); font-size: 15px; line-height: 1.5; }
.topic-more { margin-top: auto; font-size: 14px; font-weight: 600; color: var(--blue); }