/* aiotidea.com — bảng màu và khung theo design system AIOT (skill aiot-artifact-design).
   Khác một chỗ có lý do: Inter đứng trước Noto Sans JP vì site là Việt/Anh, Noto Sans JP thiếu dấu tiếng Việt. */
:root{
  --aiot-blue:#2B80FC; --aiot-blue-dark:#1B5FD0;
  --aiot-yellow:#F9C626; --aiot-green:#00C15C; --aiot-red:#E5352C;
  --aiot-ink:#111827; --aiot-gray:#6B7280;
  --aiot-line:#E5E7EB; --aiot-bg:#F7F8FA; --aiot-surface:#FFFFFF;
  --tint-blue:#EAF2FF; --tint-yellow:#FEF7E0; --tint-green:#E6F9EF; --tint-red:#FDEBEA;
  --radius:14px; --shadow:0 2px 10px rgba(17,24,39,.06); --shadow-hover:0 8px 24px rgba(17,24,39,.12);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter','Noto Sans JP','Segoe UI',system-ui,sans-serif;color:var(--aiot-ink);background:var(--aiot-bg);line-height:1.7;font-size:16px}
a{color:var(--aiot-blue)}
img{max-width:100%;display:block}
.container{max-width:1140px;margin:0 auto;padding:0 24px}
.container.narrow{max-width:760px}
section{padding:72px 0}
section.alt{background:var(--aiot-surface);border-top:1px solid var(--aiot-line);border-bottom:1px solid var(--aiot-line)}
h2.section-title{font-size:30px;font-weight:700;margin-bottom:12px;padding-left:14px;border-left:5px solid var(--aiot-blue);line-height:1.3}
h2.section-title .num{color:var(--aiot-blue);font-weight:800;margin-right:12px}
.section-lede{color:var(--aiot-gray);max-width:720px;margin-bottom:28px}

/* header: tĩnh, không sticky */
.site-header{background:var(--aiot-surface);border-bottom:1px solid var(--aiot-line)}
.site-header .container{display:flex;align-items:center;gap:24px;height:64px}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--aiot-ink);font-weight:700}
.brand img{height:38px;width:auto}
.brand-site{font-size:15px;letter-spacing:.01em}
.site-nav{display:flex;gap:20px;margin-left:auto;font-size:14px}
.site-nav a{color:var(--aiot-ink);text-decoration:none;font-weight:500}
.site-nav a:hover,.site-nav a[aria-current]{color:var(--aiot-blue)}
.lang-switch{font-size:13px;font-weight:600;text-decoration:none;border:1px solid var(--aiot-line);border-radius:999px;padding:4px 12px;color:var(--aiot-ink)}

/* hero */
.hero{background:linear-gradient(135deg,var(--aiot-blue),var(--aiot-blue-dark));color:#fff;padding:88px 0 72px;text-align:center}
.hero .eyebrow{opacity:.85;letter-spacing:.2em;font-size:13px;font-weight:600}
.hero h1{font-size:44px;font-weight:700;margin:12px 0 20px;line-height:1.2}
.hero .lede{max-width:680px;margin:0 auto;opacity:.92;font-size:18px}
.hero .stats{display:flex;gap:48px;justify-content:center;margin-top:44px;flex-wrap:wrap}
.stat-num{font-size:36px;font-weight:700;line-height:1.1}
.stat-num.accent{color:var(--aiot-yellow)}
.stat-label{font-size:13px;opacity:.8;margin-top:6px}
.hero-product{background:linear-gradient(135deg,var(--accent,var(--aiot-blue)),var(--aiot-blue-dark))}
.hero-icon{width:96px;height:96px;margin:0 auto 20px;border-radius:22px;box-shadow:0 8px 24px rgba(0,0,0,.25)}
.hero .actions.center{justify-content:center;margin-top:28px}
.hero .legal-links{margin-top:18px;font-size:13px;opacity:.85}
.hero .legal-links a{color:#fff}

/* chip nhảy mục */
.chips{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:28px}
.chip{background:var(--tint-blue);color:var(--aiot-blue);padding:8px 16px;border-radius:999px;font-size:14px;text-decoration:none;font-weight:600}
.chip span{opacity:.6;margin-right:6px}

/* card */
.card{background:var(--aiot-surface);border:1px solid var(--aiot-line);border-radius:var(--radius);box-shadow:var(--shadow);padding:28px;transition:transform .3s ease,box-shadow .3s ease}
.card:hover{transform:translateY(-2px);box-shadow:var(--shadow-hover)}
.product-card{margin-bottom:24px;scroll-margin-top:24px}
.product-head{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.product-head .num{font-size:44px;font-weight:800;color:var(--tint-blue);-webkit-text-stroke:1.5px var(--aiot-blue);line-height:1}
.product-icon{width:56px;height:56px;border-radius:14px}
.product-head h3{font-size:22px;font-weight:700;line-height:1.3}
.tagline{color:var(--aiot-gray);font-size:15px}
.badge{margin-left:auto;padding:3px 12px;border-radius:999px;font-size:12px;font-weight:600;white-space:nowrap}
.badge-green{background:var(--tint-green);color:#047a3e}
.badge-yellow{background:var(--tint-yellow);color:#8a6a00}
.badge-blue{background:var(--tint-blue);color:var(--aiot-blue)}
.product-desc{margin:18px 0 10px}
.product-points{padding-left:20px;color:var(--aiot-gray);font-size:15px}
.product-meta{font-size:13px;color:var(--aiot-gray);margin-top:12px}
.actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:16px}

/* nút */
.btn{display:inline-block;border-radius:10px;padding:12px 24px;font-weight:600;text-decoration:none;font-size:15px;border:1px solid transparent}
.btn-primary{background:var(--aiot-blue);color:#fff}
.hero .btn-primary{background:#fff;color:var(--aiot-blue-dark)}
.btn-secondary{background:var(--aiot-surface);color:var(--aiot-blue);border-color:var(--aiot-blue)}
.btn-disabled{background:rgba(255,255,255,.18);color:#fff;border-color:rgba(255,255,255,.4)}

/* bảng công ty */
.facts{width:100%;background:var(--aiot-surface);border-collapse:collapse;border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.facts th{width:200px;text-align:left;background:var(--tint-blue);padding:16px 20px;font-size:14px;vertical-align:top}
.facts td{padding:16px 20px;border-bottom:1px solid var(--aiot-line)}

/* trang sản phẩm */
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.feature h3{font-size:17px;font-weight:700;margin-bottom:8px}
.feature p{color:var(--aiot-gray);font-size:15px}

/* văn bản dài (pháp lý) */
.crumbs{font-size:13px;color:var(--aiot-gray);margin-bottom:20px}
.prose{background:var(--aiot-surface);border:1px solid var(--aiot-line);border-radius:var(--radius);padding:40px}
.prose h1{font-size:32px;margin-bottom:8px;line-height:1.25}
.prose h2{font-size:20px;margin:28px 0 8px}
.prose p,.prose li{margin-bottom:10px}
.prose ul{padding-left:22px}
.prose code{font-size:90%;background:var(--aiot-bg);padding:1px 6px;border-radius:6px}
.lede-ink{font-size:17px;margin-bottom:20px}
details.card{padding:16px 22px;margin-bottom:12px}
details.card summary{font-weight:600;cursor:pointer}
details.card p{color:var(--aiot-gray);margin-top:8px}
.legal-links{font-size:14px;margin-top:24px}

/* kết trang: không footer, một dòng nhỏ */
.site-end{text-align:center;color:var(--aiot-gray);font-size:12px;padding:24px 16px 40px}
.site-end a{color:var(--aiot-gray)}

@media(max-width:768px){
  .hero h1{font-size:32px}
  .grid-3{grid-template-columns:1fr}
  .site-nav{display:none}
  section{padding:48px 0}
  h2.section-title{font-size:24px}
  .facts th{width:120px}
  .prose{padding:24px}
}

/* liên hệ: hộp chung + mỗi sản phẩm một hộp */
.contact-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.card.contact{padding:20px}
.card.contact h3{font-size:15px;font-weight:600;margin-bottom:12px;color:var(--aiot-gray)}
.card.contact .btn{padding:10px 14px;font-size:14px;word-break:break-all}
@media(max-width:900px){.contact-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:520px){.contact-grid{grid-template-columns:1fr}}

/* chuyển phiên bản theo hệ điều hành (?os=android) */
.os-switch{font-size:13px;color:var(--aiot-gray);margin:0 0 16px}
.hero .os-switch{color:#fff;opacity:.85;margin-top:10px}
.hero .os-switch a{color:#fff}