:root{
  --bg:#f7f9fc;
  --bg-2:#eef4ff;
  --card:#ffffff;
  --text:#0f172a;
  --muted:#53627a;
  --line:#dbe4f0;
  --brand:#1d4ed8;
  --brand-2:#2563eb;
  --brand-3:#0f67ff;
  --soft:#eff6ff;
  --shadow:0 18px 50px rgba(15,23,42,.08);
  --shadow-soft:0 10px 26px rgba(37,99,235,.08);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
  background:
    radial-gradient(circle at top left, rgba(37,99,235,.08), transparent 34%),
    radial-gradient(circle at top right, rgba(29,78,216,.08), transparent 28%),
    linear-gradient(180deg,#ffffff 0%,var(--bg) 100%);
  color:var(--text);
  line-height:1.72;
  text-rendering:optimizeLegibility;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
.container{width:min(1140px,calc(100% - 32px));margin:0 auto}
.narrow{width:min(820px,calc(100% - 32px))}
.site-header{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.82);
  backdrop-filter:blur(16px);
  border-bottom:1px solid rgba(219,228,240,.9);
  box-shadow:0 6px 20px rgba(15,23,42,.04);
}
.nav-wrap{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:16px 0}
.logo{font-size:1.08rem;font-weight:900;letter-spacing:-.03em;color:var(--brand)}
.nav{display:flex;flex-wrap:wrap;gap:18px;color:var(--muted);font-size:.95rem;font-weight:500}
.nav a{padding:8px 0;border-bottom:2px solid transparent;transition:color .2s ease,border-color .2s ease}
.nav a:hover{color:var(--brand);border-color:rgba(29,78,216,.3)}
.hero{padding:58px 0 30px;position:relative}
.hero::before{
  content:"";
  position:absolute;inset:0 0 auto;
  height:420px;
  pointer-events:none;
  background:linear-gradient(180deg,rgba(255,255,255,.92) 0%, rgba(255,255,255,0) 100%);
}
.hero-grid{position:relative;display:grid;grid-template-columns:1.3fr .95fr;gap:24px;align-items:start}
.hero h1{font-size:clamp(2.15rem,4vw,3.9rem);line-height:1.05;margin:16px 0 16px;letter-spacing:-.05em;max-width:12ch}
.lead,.article-lead{font-size:1.05rem;color:var(--muted);max-width:62ch;margin:0}
.article-meta{
  display:flex;
  flex-wrap:wrap;
  gap:10px;
  margin:18px 0 0;
}
.article-meta span{
  display:inline-flex;
  align-items:center;
  padding:8px 12px;
  border-radius:999px;
  background:rgba(255,255,255,.92);
  border:1px solid var(--line);
  box-shadow:var(--shadow-soft);
  color:#334155;
  font-size:.84rem;
  font-weight:700;
}
.article-cover{
  margin:22px 0 8px;
  aspect-ratio:1200/630;
  border-radius:28px;
  overflow:hidden;
  border:1px solid rgba(203,213,225,.9);
  box-shadow:var(--shadow);
  background:#fff;
}
.article-cover img{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
}
.pill,.tag{
  display:inline-flex;align-items:center;gap:6px;
  padding:8px 12px;border-radius:999px;
  background:linear-gradient(180deg,#f4f8ff 0%, #eaf2ff 100%);
  color:var(--brand);
  font-weight:800;
  font-size:.82rem;
  letter-spacing:.01em;
  box-shadow:inset 0 0 0 1px rgba(29,78,216,.08);
}
.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:22px}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:12px 18px;border-radius:14px;font-weight:800;border:1px solid var(--line);transition:transform .16s ease,box-shadow .16s ease,background .16s ease,border-color .16s ease}
.btn:hover{transform:translateY(-1px)}
.btn-primary{background:linear-gradient(135deg,var(--brand),var(--brand-3));border-color:transparent;color:#fff;box-shadow:0 14px 30px rgba(29,78,216,.22)}
.btn-primary:hover{box-shadow:0 18px 36px rgba(29,78,216,.28)}
.btn-secondary{background:#fff;color:var(--text);box-shadow:var(--shadow-soft)}

.hero-card,.card{
  background:linear-gradient(180deg,#fff 0%, #fbfdff 100%);
  border:1px solid var(--line);
  border-radius:26px;
  box-shadow:var(--shadow);
}
.hero-card{padding:22px;position:relative;overflow:hidden}
.hero-card::after{
  content:"";
  position:absolute;inset:auto -30px -30px auto;width:110px;height:110px;border-radius:50%;
  background:radial-gradient(circle, rgba(37,99,235,.14) 0%, rgba(37,99,235,0) 70%);
}
.hero-card h2,.section h2{margin:0 0 10px;letter-spacing:-.04em}
.hero-card ul{padding-left:18px;color:var(--muted);margin:14px 0 0;display:grid;gap:10px}
.hero-highlights{
  margin-top:18px;
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:12px;
}
.hero-highlights > div{
  padding:14px 15px;
  border-radius:18px;
  background:rgba(255,255,255,.85);
  border:1px solid rgba(219,228,240,.95);
  box-shadow:var(--shadow-soft);
}
.hero-highlights strong{display:block;font-size:.9rem;margin-bottom:4px;letter-spacing:-.01em}
.hero-highlights span{display:block;color:var(--muted);font-size:.92rem;line-height:1.5}
.section{padding:28px 0}
.section.alt{background:linear-gradient(180deg, rgba(255,255,255,.58), rgba(255,255,255,.82));border-top:1px solid rgba(219,228,240,.72);border-bottom:1px solid rgba(219,228,240,.72)}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:16px;margin-bottom:18px}
.section-head h2{font-size:1.55rem;position:relative;padding-bottom:10px}
.section-head h2::after{
  content:"";
  position:absolute;left:0;bottom:0;width:64px;height:3px;border-radius:999px;
  background:linear-gradient(90deg,var(--brand),rgba(37,99,235,.15));
}
.section-head p{margin:0;color:var(--muted);max-width:60ch}
.grid{display:grid;gap:18px}
.cards-6{grid-template-columns:repeat(3,1fr)}
.cards-3{grid-template-columns:repeat(3,1fr)}
.cards-2{grid-template-columns:repeat(2,1fr)}
.cat-card,.info-card,.post-card{padding:20px}
.cat-card{
  background:linear-gradient(180deg,#fff 0%, #f9fbff 100%);
}
.post-card{display:flex;flex-direction:column;height:100%;transition:transform .18s ease,box-shadow .18s ease,border-color .18s ease;background:linear-gradient(180deg,#fff 0%, #fcfdff 100%)}
.post-card:hover{transform:translateY(-3px);border-color:#bfd0ff;box-shadow:0 22px 42px rgba(15,23,42,.1)}
.post-card h3{margin:12px 0 8px;letter-spacing:-.035em;line-height:1.22;font-size:1.02rem}
.post-card p,.info-card p,.cat-card p{color:var(--muted);margin:0;font-size:.96rem}
#gioi-thieu,.article-wrap{padding-top:14px}
.site-footer{padding:26px 0 40px;border-top:1px solid var(--line);margin-top:20px;background:rgba(255,255,255,.7)}
.footer-grid{display:flex;justify-content:space-between;gap:24px;color:var(--muted)}
.footer-grid strong{color:var(--text)}
.article{padding:30px 0 46px}
.article h1{font-size:clamp(2rem,4vw,3.25rem);line-height:1.08;letter-spacing:-.05em;margin:14px 0 14px;max-width:14ch}
.article h2{margin-top:34px;letter-spacing:-.03em}
.article p{margin:0 0 16px}
.article p,.article li{font-size:1.02rem;color:#1e293b}
.article ul,.article ol{padding-left:22px}
.toc{padding:18px 20px;margin:24px 0;background:linear-gradient(180deg,#fff 0%,#f8fbff 100%);border-radius:22px;box-shadow:var(--shadow-soft);border:1px solid var(--line)}
.toc strong{font-size:.92rem;letter-spacing:.02em;text-transform:uppercase;color:var(--brand)}
.toc ol{margin:10px 0 0;padding-left:18px;color:var(--muted)}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:20px;background:#fff;box-shadow:var(--shadow)}
table{width:100%;border-collapse:collapse;min-width:640px}
th,td{padding:14px 16px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
th{background:#f8fbff;font-size:.92rem;color:#334155}
.callout{padding:18px 20px;background:linear-gradient(180deg,#eff6ff 0%, #f8fbff 100%);border:1px solid #bfdbfe;border-radius:20px;margin:26px 0;box-shadow:var(--shadow-soft)}
.ad-slot{
  margin:28px 0;
  min-height:160px;
  content-visibility:auto;
  contain-intrinsic-size:160px;
  padding:18px;
  border:1px dashed #cbd5e1;
  border-radius:22px;
  background:linear-gradient(180deg,#ffffff 0%,#f8fbff 100%);
  color:#475569;
}
.ad-slot__label{
  display:inline-flex;
  align-items:center;
  gap:6px;
  font-size:.76rem;
  font-weight:900;
  letter-spacing:.08em;
  text-transform:uppercase;
  color:#1d4ed8;
  margin-bottom:10px;
}
.ad-slot__box{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  min-height:90px;
  padding:16px 18px;
  border-radius:18px;
  background:linear-gradient(135deg,#eff6ff 0%,#ffffff 100%);
  border:1px solid #dbeafe;
}
.ad-slot__title{font-weight:800;color:#0f172a;margin:0}
.ad-slot__note{margin:4px 0 0;color:#64748b;font-size:.95rem}
.related ul{list-style:none;padding-left:0;margin:0;display:grid;gap:12px}
.related li{margin:0}
.related a{
  display:block;
  padding:14px 16px;
  border:1px solid var(--line);
  border-radius:16px;
  background:#fff;
  box-shadow:var(--shadow-soft);
  color:var(--brand);
  transition:transform .18s ease,border-color .18s ease,box-shadow .18s ease;
}
.related a:hover{transform:translateY(-1px);border-color:#bfd0ff;box-shadow:0 18px 34px rgba(15,23,42,.08)}
.section,.card,.post-card,.cat-card,.info-card,.toc,.callout,.ad-slot,.hero-card{
  content-visibility:auto;
  contain-intrinsic-size:1px 320px;
}
@media (max-width: 860px){
  body{background:#f7f9fc}
  .site-header{position:static;backdrop-filter:none;background:rgba(255,255,255,.95)}
  .hero::before{display:none}
  .hero-grid,.cards-6,.cards-3,.cards-2,.hero-highlights{grid-template-columns:1fr}
  .section-head,.footer-grid{display:grid;grid-template-columns:1fr}
  .nav-wrap{flex-direction:column;align-items:flex-start}
  .nav{gap:12px}
  .hero{padding-top:34px}
  .hero h1{max-width:100%}
}
@media (max-width: 560px){
  .container,.narrow{width:min(100% - 20px,1120px)}
  .hero h1,.article h1{font-size:2rem}
  .btn{width:100%}
  .hero-actions{display:grid}
  .section{padding:22px 0}
  .post-card,.cat-card,.info-card,.hero-card,.toc,.callout{border-radius:18px}
  .ad-slot__box{display:grid}
  .section-more{margin-top:16px}
}