:root {
  --primary-blue: #4A90E2;
  --primary-blue-dark: #3B72B5;
  --primary-blue-light: #DCEBFA;
  --accent-green: #7BC96F;
  --accent-green-dark: #5FA855;
  --off-white: #F7F9FC;
  --text-primary: #232B36;
  --text-secondary: #6E7A8A;
  --border: #E5EAF1;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Be Vietnam Pro', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text-primary);
  background: #fff;
  line-height: 1.6;
}
a { color: var(--primary-blue-dark); text-decoration: none; }
img { max-width: 100%; display: block; }
.container { max-width: 1160px; margin: 0 auto; padding: 0 24px; }
svg.icon { width: 20px; height: 20px; flex-shrink: 0; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; }

.site-header {
  position: sticky; top: 0; z-index: 20;
  background: rgba(255,255,255,0.94); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 66px; }
.site-header .brand { display: flex; align-items: center; gap: 9px; font-weight: 800; font-size: 18px; color: var(--primary-blue-dark); }
.site-header .brand img { height: 32px; }
.site-nav { display: flex; align-items: center; gap: 26px; }
.site-nav a { color: var(--text-primary); font-weight: 600; font-size: 14px; transition: color .15s; }
.site-nav a:hover { color: var(--primary-blue-dark); }
.site-nav a.nav-cta { background: var(--primary-blue); color: #fff; padding: 9px 18px; border-radius: 999px; }
.site-nav a.nav-cta:hover { background: var(--primary-blue-dark); color: #fff; }

/* ---------- HERO ---------- */
.hero { background: linear-gradient(180deg, #EEF6FF 0%, #F7FCFA 100%); padding: 36px 0 30px; }
.hero .container { text-align: center; }
.hero-image-full { width: 100%; max-width: 1000px; margin: 0 auto 22px; border-radius: 20px; box-shadow: 0 24px 48px rgba(59,114,181,0.16); }
.hero p.tagline { font-size: 16.5px; color: var(--text-secondary); max-width: 560px; margin: 0 auto 26px; }
.download-row { display: flex; justify-content: center; gap: 14px; flex-wrap: wrap; }

.btn-store {
  display: inline-flex; align-items: center; gap: 11px;
  background: #1B2330; color: #fff; padding: 10px 18px; border-radius: 12px;
  box-shadow: 0 6px 16px rgba(27,35,48,0.2); transition: transform .15s, box-shadow .15s;
}
.btn-store:hover { transform: translateY(-2px); box-shadow: 0 10px 22px rgba(27,35,48,0.28); color: #fff; }
.btn-store[disabled] { opacity: 0.55; pointer-events: none; }
.btn-store .store-icon { width: 24px; height: 24px; flex-shrink: 0; }
.btn-store .store-text { display: flex; flex-direction: column; line-height: 1.25; text-align: left; }
.btn-store .store-text small { font-size: 10px; opacity: 0.75; font-weight: 500; letter-spacing: .3px; }
.btn-store .store-text strong { font-size: 14.5px; font-weight: 700; }

section { padding: 56px 0; }
section h2 { text-align: center; font-size: 27px; margin: 0 0 8px; font-weight: 800; }
section p.section-sub { text-align: center; color: var(--text-secondary); max-width: 500px; margin: 0 auto 34px; font-size: 15px; }

/* Tinh nang - khong dung icon tu ve, dung so thu tu + chu de gon gang */
.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 4px 28px; max-width: 900px; margin: 0 auto; }
.feature-row { display: flex; align-items: flex-start; gap: 14px; padding: 16px 0; border-bottom: 1px solid var(--border); text-align: left; }
.feature-row .num {
  flex-shrink: 0; width: 32px; height: 32px; border-radius: 50%;
  background: var(--primary-blue); color: #fff; font-weight: 800; font-size: 13.5px;
  display: flex; align-items: center; justify-content: center;
}
.feature-row h3 { font-size: 15.5px; margin: 0 0 4px; }
.feature-row p { font-size: 13.5px; color: var(--text-secondary); margin: 0; }

.download-panel {
  background: linear-gradient(135deg, #EAF3FF 0%, #E3FBF3 100%);
  border-radius: 24px; padding: 44px 40px; text-align: center;
}
.download-panel h2 { color: var(--text-primary); }

.blog-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 22px; }
.blog-card {
  background: #fff; border: 1px solid var(--border); border-radius: 14px; overflow: hidden;
  display: flex; flex-direction: column; transition: transform .18s, box-shadow .18s;
}
.blog-card:hover { transform: translateY(-4px); box-shadow: 0 14px 26px rgba(59,114,181,0.12); }
.blog-card .cover { width: 100%; aspect-ratio: 1.91; object-fit: cover; background: var(--primary-blue-light); }
.blog-card .body { padding: 18px 20px; flex: 1; display: flex; flex-direction: column; }
.blog-card .date { font-size: 12px; color: var(--text-secondary); margin-bottom: 6px; }
.blog-card h3 { font-size: 15.5px; margin: 0 0 8px; }
.blog-card p.excerpt { font-size: 13px; color: var(--text-secondary); flex: 1; margin: 0 0 14px; }
.blog-card .read-more { font-weight: 700; font-size: 12.5px; color: var(--primary-blue-dark); }
.empty-note { text-align: center; color: var(--text-secondary); padding: 24px; grid-column: 1 / -1; }

.site-footer { background: #1B2330; color: #9AA7B6; padding: 38px 0; text-align: center; font-size: 13px; }
.site-footer .brand { color: #fff; font-weight: 800; font-size: 16px; margin-bottom: 8px; }

.page-header { background: linear-gradient(135deg, var(--primary-blue), var(--primary-blue-dark)); color: #fff; padding: 44px 0; text-align: center; }
.page-header h1 { margin: 0; font-size: 27px; font-weight: 800; }

.article-detail { background: #fff; border-radius: 16px; border: 1px solid var(--border); padding: 34px; max-width: 760px; margin: 0 auto; }
.article-detail .cover { width: 100%; border-radius: 12px; margin-bottom: 22px; aspect-ratio: 1.91; object-fit: cover; }
.article-detail h1 { font-size: 25px; margin: 0 0 8px; }
.article-detail .date { color: var(--text-secondary); font-size: 13px; margin-bottom: 22px; }
.article-detail .content { white-space: pre-line; font-size: 15px; }
.back-link { display: inline-flex; align-items: center; gap: 6px; margin-bottom: 16px; font-weight: 700; font-size: 14px; }

@media (max-width: 640px) {
  .site-nav { gap: 12px; }
  .site-nav a:not(.nav-cta) { display: none; }
  .download-panel { padding: 34px 20px; }
  section { padding: 42px 0; }
}