/* ========== GOCheap – Cầu Giấy: SEO-friendly, responsive CSS ========== */
:root{
  --brand:#0B5FFF; /* primary */
  --brand-2:#00C2FF; /* accent */
  --text:#111827; /* gray-900 */
  --muted:#4B5563; /* gray-600 */
  --bg:#ffffff;
  --surface:#F8FAFC; /* slate-50 */
  --border:#E5E7EB; /* gray-200 */
  --success:#059669;
  --danger:#DC2626;
  --radius:14px;
  --shadow:0 8px 30px rgba(2,6,23,.08);
  --maxw:1120px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; color:var(--text); background:var(--bg);
  font:400 16px/1.65 system-ui,-apple-system,Segoe UI,Roboto,Inter,Arial,sans-serif;
}
img{max-width:100%; height:auto; display:block}
a{color:var(--brand); text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:var(--maxw); margin-inline:auto; padding: clamp(16px, 3vw, 28px)}
.skip-link{position:absolute;left:-9999px;top:auto;width:1px;height:1px;overflow:hidden}
.skip-link:focus{left:16px;top:16px;width:auto;height:auto;padding:10px 14px;background:#000;color:#fff;border-radius:8px;z-index:9999}

/* Header */
.header{position:sticky;top:0;background:rgba(255,255,255,.9);backdrop-filter:saturate(160%) blur(8px);border-bottom:1px solid var(--border);z-index:50}
.nav{display:flex;align-items:center;gap:16px}
.brand{display:flex;align-items:center;gap:10px;font-weight:700}
.brand img{width:28px;height:28px}
.navbar{display:flex;align-items:center;gap:16px;margin-left:auto}
.navbar a{padding:8px 10px;border-radius:10px}
.cta{background:var(--brand);color:#fff;box-shadow:var(--shadow)}
.cta:hover{filter:brightness(.95);text-decoration:none}
.menu-btn{display:none;background:transparent;border:1px solid var(--border);padding:8px 10px;border-radius:10px}

/* Hero */
.hero{background:linear-gradient(180deg, rgba(11,95,255,.06), transparent);}
.hero .wrap{display:grid;grid-template-columns:1.25fr .75fr;gap:28px;align-items:center}
.badge{display:inline-flex;gap:8px;align-items:center;padding:6px 10px;border:1px solid var(--border);border-radius:999px;background:#fff}
.badge .dot{width:8px;height:8px;border-radius:50%;background:var(--success)}
.h1{font-size: clamp(28px, 4.2vw, 44px); line-height:1.15; margin: 10px 0 12px}
.lead{font-size: clamp(16px, 2.2vw, 18px); color:var(--muted)}
.hero-img{border-radius:var(--radius); box-shadow:var(--shadow)}
.kpis{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:14px}
.kpis div{padding:12px 14px;border:1px dashed var(--border);border-radius:14px;background:#fff;text-align:center}
.kpis .n{font-weight:700;font-size:20px}

/* Sections */
section{scroll-margin-top:80px}
.section{padding: clamp(24px, 5vw, 56px) 0}
.section h2{font-size: clamp(22px, 3.2vw, 32px); margin:0 0 14px}
.card{background:#fff;border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow)}
.card-pad{padding: clamp(14px, 2.2vw, 24px)}
.grid{display:grid; gap:16px}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-4{grid-template-columns:repeat(4,1fr)}

/* Lists */
.check li{margin:8px 0; list-style: none; padding-left:28px; position:relative}
.check li::before{content:"✔"; position:absolute; left:0; top:0; color:var(--success)}

/* Tables */
.table{width:100%; border-collapse:separate; border-spacing:0; overflow:hidden; border-radius:12px; border:1px solid var(--border); background:#fff; box-shadow:var(--shadow)}
.table th, .table td{padding:12px 14px; text-align:left; border-bottom:1px solid var(--border)}
.table thead th{background:var(--surface); font-weight:700}
.table tr:last-child td{border-bottom:none}

/* CTA block */
.cta-block{display:grid; grid-template-columns:1fr auto; gap:16px; align-items:center; padding:18px; border:1px solid var(--border); border-radius:14px; background:linear-gradient(180deg,#fff, #F0F7FF)}
.btn{display:inline-flex; align-items:center; gap:10px; padding:10px 14px; border-radius:12px; border:1px solid var(--border); background:#fff}
.btn.primary{background:var(--brand); color:#fff; border-color:transparent}
.btn.ghost{background:#fff}

/* Footer */
.footer{background:#0b1220; color:#e5e7eb}
.footer a{color:#c7d2fe}
.footer .small{color:#94a3b8}

/* Utilities */
.m0{margin:0} .mt8{margin-top:8px} .mt12{margin-top:12px} .mt16{margin-top:16px} .mt24{margin-top:24px} .mt32{margin-top:32px} .mt40{margin-top:40px}

/* Responsive */
@media (max-width: 900px){
  .hero .wrap{grid-template-columns:1fr}
  .kpis{grid-template-columns:repeat(3,1fr)}
  .grid-2{grid-template-columns:1fr}
  .grid-3{grid-template-columns:repeat(2,1fr)}
}
@media (max-width: 640px){
  .navbar{display:none}
  .menu-btn{display:inline-flex}
  .kpis{grid-template-columns:repeat(2,1fr)}
}

/* Print tweaks */
@media print{
  .header, .cta, .menu-btn, .btn{display:none !important}
  a::after{content:" (" attr(href) ")"; font-size:12px}
}