/* ===== Bintech v2 — Theme (giao diện sáng, font Inter, màu logo) ===== */
:root{
  --brand:#0A86C8; --brand-dark:#085A89; --brand-deep:#0C3552; --brand-soft:#EEF7FC;
  --accent:#F7941D; --accent-dark:#B35900;
  --ink:#14243A; --body:#4A5B70; --muted:#7B8BA0; --line:#E3EAF2; --panel:#F5F9FC;
  --radius:14px; --shadow:0 8px 28px rgba(20,36,58,.08); --shadow-lg:0 18px 48px rgba(20,36,58,.14);
}
html{scroll-behavior:smooth}
body{font-family:Inter,system-ui,"Segoe UI",Arial,sans-serif;color:var(--body);background:#fff;-webkit-font-smoothing:antialiased}
h1,h2,h3,h4{color:var(--ink);letter-spacing:-.01em}
img{max-width:100%}
.wrap{max-width:1200px;margin:0 auto;padding:0 20px}

/* --- Header --- */
.bt-top{background:var(--brand-deep);color:#C9DCEB;font-size:13px}
.bt-top a:hover{color:#fff}
.bt-header{position:sticky;top:0;z-index:60;background:rgba(255,255,255,.94);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.bt-nav a.lnk{padding:9px 12px;border-radius:8px;font-weight:600;font-size:15px;color:var(--ink);white-space:nowrap}
.bt-nav a.lnk:hover,.bt-nav a.lnk.active{color:var(--brand);background:var(--brand-soft)}
@media (max-width:1279px){
  /* backdrop-filter biến header thành khung chứa của phần tử fixed → menu & nền tối bị kẹt trong header */
  .bt-header{backdrop-filter:none;background:#fff}
  .bt-nav{position:fixed;top:0;right:0;height:100vh;width:min(320px,86vw);background:#fff;flex-direction:column;align-items:stretch!important;
    padding:76px 18px 24px;gap:4px!important;box-shadow:var(--shadow-lg);transform:translateX(100%);transition:transform .28s ease;z-index:70;overflow-y:auto}
  .bt-nav.open{transform:none}
  .bt-nav a.lnk{padding:12px 14px}
}
.bt-overlay{position:fixed;inset:0;background:rgba(12,53,82,.45);z-index:65;opacity:0;pointer-events:none;transition:.25s}
.bt-overlay.show{opacity:1;pointer-events:auto}

/* --- Buttons --- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 22px;border-radius:10px;font-weight:700;font-size:15px;transition:.2s;cursor:pointer;border:2px solid transparent;line-height:1.2}
.btn-primary{background:var(--brand);color:#fff;box-shadow:0 8px 20px rgba(10,134,200,.28)}
.btn-primary:hover{background:var(--brand-dark);transform:translateY(-1px)}
.btn-accent{background:var(--accent);color:var(--brand-deep);box-shadow:0 8px 20px rgba(247,148,29,.32)}
.btn-accent:hover{background:var(--accent-dark);color:#fff;transform:translateY(-1px)}
.btn-ghost{border-color:var(--brand-dark);color:var(--brand-dark);background:#fff}
.btn-ghost:hover{background:var(--brand-soft)}
.btn-white{border-color:#fff;color:#fff}
.btn-white:hover{background:rgba(255,255,255,.12)}
.btn:disabled{opacity:.6;cursor:wait}

/* --- Section heads, cards --- */
.eyebrow{display:inline-block;font-size:12px;font-weight:800;letter-spacing:.14em;text-transform:uppercase;color:var(--accent-dark);margin-bottom:8px}
.sec-title{font-size:clamp(26px,3.4vw,38px);font-weight:800;line-height:1.2}
.bar{width:56px;height:4px;border-radius:4px;background:linear-gradient(90deg,var(--brand),var(--accent));margin:14px auto 0}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;transition:.25s;display:flex;flex-direction:column}
.card:hover{box-shadow:var(--shadow-lg);transform:translateY(-4px);border-color:transparent}
.card .thumb{aspect-ratio:16/10;overflow:hidden;background:var(--panel)}
.card .thumb img{width:100%;height:100%;object-fit:cover;transition:transform .5s}
.card:hover .thumb img{transform:scale(1.05)}
.tag{display:inline-block;font-size:12px;font-weight:700;color:var(--brand);background:var(--brand-soft);padding:4px 10px;border-radius:999px}
.price{font-weight:800;color:var(--accent-dark);font-size:20px}
.price small{font-size:12px;color:var(--muted);font-weight:600}

/* --- Hero slider --- */
.hero{position:relative;min-height:clamp(480px,74vh,680px);overflow:hidden;background:var(--brand-deep)}
.hero-slide{position:absolute;inset:0;background-size:cover;background-position:center;opacity:0;transition:opacity 1s ease;display:flex;align-items:center}
.hero-slide::before{content:"";position:absolute;inset:0;background:linear-gradient(100deg,rgba(12,53,82,.92) 0%,rgba(12,53,82,.65) 48%,rgba(12,53,82,.15) 100%)}
.hero-slide.active{opacity:1;z-index:1}
.hero-slide>.wrap{position:relative;width:100%}
.hero-dots{position:absolute;bottom:22px;left:50%;transform:translateX(-50%);display:flex;gap:8px;z-index:3}
.hero-dots button{width:10px;height:10px;border-radius:99px;background:rgba(255,255,255,.5);transition:.3s}
.hero-dots button.active{width:30px;background:var(--accent)}

/* --- Page hero (trang con) --- */
.page-hero{background:linear-gradient(120deg,var(--brand-deep),var(--brand-dark) 60%,var(--brand));color:#fff;padding:56px 0 48px;position:relative;overflow:hidden}
.page-hero::after{content:"";position:absolute;right:-120px;top:-120px;width:360px;height:360px;border-radius:50%;border:40px solid rgba(247,148,29,.18)}
.page-hero h1{color:#fff;font-size:clamp(28px,4vw,42px);font-weight:800}
.crumb{font-size:13px;color:#BFD6E8}.crumb a:hover{color:#fff}

/* --- Bảng, form --- */
.spec{width:100%;border-collapse:collapse;font-size:14px}
.spec th,.spec td{padding:11px 14px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top}
.spec thead th{background:var(--brand-deep);color:#fff;font-weight:700;white-space:nowrap}
.spec tbody tr:nth-child(even){background:var(--panel)}
.tbl-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:var(--radius)}
.fld label{display:block;font-weight:600;font-size:14px;color:var(--ink);margin-bottom:6px}
.fld input,.fld select,.fld textarea{width:100%;border:1.5px solid var(--line);border-radius:10px;padding:11px 14px;font:inherit;font-size:15px;background:#fff;transition:.2s;color:var(--ink)}
.fld input:focus,.fld select:focus,.fld textarea:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 4px rgba(10,134,200,.12)}
.form-msg{display:none;margin-top:14px;padding:12px 14px;border-radius:10px;font-weight:600;font-size:14px}
.form-msg.ok{display:block;background:#E8F7EF;color:#157347}
.form-msg.err{display:block;background:#FDECEC;color:#B42318}

/* --- FAQ --- */
.faq details{border:1px solid var(--line);border-radius:12px;background:#fff;margin-bottom:10px}
.faq summary{cursor:pointer;padding:16px 48px 16px 18px;font-weight:700;color:var(--ink);list-style:none;position:relative}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";position:absolute;right:18px;top:12px;font-size:22px;color:var(--brand);transition:.2s}
.faq details[open] summary::after{transform:rotate(45deg)}
.faq details p{padding:0 18px 16px;margin:0}

/* --- Bài viết --- */
.prose-bt{color:var(--body);line-height:1.8;font-size:17px}
.prose-bt h2{font-size:24px;font-weight:800;margin:32px 0 12px}
.prose-bt h3{font-size:19px;font-weight:700;margin:24px 0 10px}
.prose-bt p{margin:0 0 16px}
.prose-bt ul,.prose-bt ol{margin:0 0 16px 22px}
.prose-bt ul{list-style:disc}.prose-bt ol{list-style:decimal}
.prose-bt li{margin-bottom:6px}
.prose-bt a{color:var(--brand);text-decoration:underline}
.prose-bt img{border-radius:12px;margin:18px 0}
.prose-bt blockquote{border-left:4px solid var(--accent);background:var(--panel);padding:12px 18px;border-radius:0 10px 10px 0;margin:0 0 16px}
.prose-bt table{display:block;overflow-x:auto;width:100%;border-collapse:collapse;margin:0 0 16px;font-size:15px}
.prose-bt th,.prose-bt td{border:1px solid var(--line);padding:8px 12px}
.prose-bt th{background:var(--panel)}

/* --- Nút nổi gọi điện / Zalo --- */
.fab{position:fixed;left:18px;bottom:22px;z-index:55;display:flex;flex-direction:column;gap:10px}
.fab a{width:50px;height:50px;border-radius:50%;display:flex;align-items:center;justify-content:center;color:#fff;font-weight:800;font-size:13px;box-shadow:var(--shadow-lg);transition:.2s}
.fab a:hover{transform:scale(1.08)}
.fab .f-phone{background:#16A34A;animation:ring 2.2s infinite}
.fab .f-zalo{background:#0068FF}
@keyframes ring{0%,100%{box-shadow:0 0 0 0 rgba(22,163,74,.5)}70%{box-shadow:0 0 0 14px rgba(22,163,74,0)}}

/* --- Hiệu ứng khi cuộn --- */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .6s ease,transform .6s ease}
.reveal.in{opacity:1;transform:none}
@media (prefers-reduced-motion:reduce){.reveal{opacity:1;transform:none;transition:none}.hero-slide{transition:none}.fab .f-phone{animation:none}}

/* --- Khung chat tư vấn --- */
.chat-btn{position:fixed;right:18px;bottom:22px;z-index:56;height:56px;padding:0 20px 0 16px;border-radius:999px;background:var(--brand);color:#fff;font-weight:700;display:flex;align-items:center;gap:10px;box-shadow:0 12px 30px rgba(10,134,200,.4);transition:.2s}
.chat-btn:hover{background:var(--brand-dark)}
.chat-btn .dot{width:9px;height:9px;border-radius:50%;background:#4ADE80;box-shadow:0 0 0 3px rgba(74,222,128,.3)}
.chat-box{position:fixed;right:18px;bottom:90px;z-index:57;width:min(380px,calc(100vw - 24px));height:min(560px,calc(100vh - 120px));background:#fff;border-radius:18px;box-shadow:0 24px 64px rgba(12,53,82,.28);display:none;flex-direction:column;overflow:hidden;border:1px solid var(--line)}
.chat-box.open{display:flex}
.chat-head{background:linear-gradient(120deg,var(--brand-deep),var(--brand));color:#fff;padding:14px 16px;display:flex;align-items:center;gap:10px}
.chat-body{flex:1;overflow-y:auto;padding:14px;background:var(--panel);display:flex;flex-direction:column;gap:10px}
.msg{max-width:86%;padding:10px 13px;border-radius:14px;font-size:14px;line-height:1.55;white-space:pre-line}
.msg.bot{background:#fff;border:1px solid var(--line);color:var(--ink);border-bottom-left-radius:4px;align-self:flex-start}
.msg.me{background:var(--brand);color:#fff;border-bottom-right-radius:4px;align-self:flex-end}
.msg a{color:var(--brand);text-decoration:underline;font-weight:600}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chips button{font-size:13px;padding:6px 11px;border-radius:999px;border:1px solid var(--brand-200,#A9D6F0);background:#fff;color:var(--brand-dark);font-weight:600}
.chips button:hover{background:var(--brand-soft)}
.chat-foot{display:flex;gap:8px;padding:10px;border-top:1px solid var(--line);background:#fff}
.chat-foot input{flex:1;border:1.5px solid var(--line);border-radius:10px;padding:10px 12px;font:inherit;font-size:14px}
.chat-foot input:focus{outline:none;border-color:var(--brand)}
.chat-foot button{background:var(--brand);color:#fff;border-radius:10px;padding:0 14px;font-weight:700}
@media (max-width:640px){.chat-btn .lbl{display:none}.chat-btn{padding:0;width:56px;justify-content:center}}

/* Giữ chỗ cho header chèn bằng JS → tránh trang bị nhảy (CLS) */
#bt-header{display:block;min-height:73px}
@media (min-width:768px){#bt-header{min-height:109px}}