/* ============================================================
   AI Native Lab — CEO AI OS · Design system
   "Đất nung và ống nghiệm": gốm Việt ấm + sắc ngọc phòng lab.
   Quy tắc màu: Cream + Ink + 1–2 màu nhấn / ấn phẩm. Tránh xanh dương công nghệ.
   Font: Be Vietnam Pro (mọi text tiếng Việt) · Bricolage Grotesque (chỉ display tiếng Anh / wordmark).
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;600;700;800&family=Bricolage+Grotesque:opsz,wght@12..96,600;12..96,700;12..96,800&family=Noto+Sans:wght@400;500;600&display=swap');

:root {
  --cream: #f5efd9;
  --cream-card: #fbf7ea;
  --ink: #1f2937;
  --ink-soft: #44505f;
  --muted: #6b6f5e;
  --orange: #f47c30;
  --orange-600: #e0691f;
  --green: #9bc990;
  --green-700: #5f8f57;
  --yellow: #f4b82e;
  --dark: #141a22;
  --line: #e6dcc0;
  --line-soft: #efe7d0;

  --font-body: 'Be Vietnam Pro', 'Noto Sans', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --font-en: 'Bricolage Grotesque', 'Be Vietnam Pro', system-ui, sans-serif;

  --r: 14px;
  --r-lg: 22px;
  --r-pill: 999px;
  --shadow: 0 1px 2px rgba(31, 41, 55, .05), 0 10px 30px -12px rgba(31, 41, 55, .14);
  --shadow-lg: 0 20px 60px -22px rgba(31, 41, 55, .3);
  --wrap: 1120px;
  --section-y: clamp(56px, 8vw, 104px);
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--cream);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
:focus-visible { outline: 3px solid var(--orange); outline-offset: 2px; border-radius: 4px; }

/* ---------- Layout ---------- */
.wrap { width: min(100% - 40px, var(--wrap)); margin-inline: auto; }
.section { padding-block: var(--section-y); }
.section--tight { padding-block: clamp(40px, 6vw, 72px); }
.section--dark { background: var(--dark); color: var(--cream); }
.section--dark .lead, .section--dark .muted { color: rgba(245, 239, 217, .72); }
.center { text-align: center; }
.maxw-680 { max-width: 680px; }
.maxw-760 { max-width: 760px; }
.mx-auto { margin-inline: auto; }

/* ---------- Typography ---------- */
h1, h2, h3, h4 { font-weight: 800; line-height: 1.12; letter-spacing: -.01em; margin: 0 0 .5em; }
h1 { font-size: clamp(2.1rem, 5.2vw, 3.5rem); }
h2 { font-size: clamp(1.7rem, 3.6vw, 2.6rem); letter-spacing: -.02em; }
h3 { font-size: clamp(1.15rem, 2vw, 1.4rem); }
p { margin: 0 0 1rem; }
.font-en { font-family: var(--font-en); letter-spacing: -.02em; }
.lead { font-size: clamp(1.05rem, 1.8vw, 1.3rem); color: var(--ink-soft); line-height: 1.6; }
.muted { color: var(--muted); }
.small { font-size: .9rem; }
.eyebrow {
  display: inline-block; font-size: .8rem; font-weight: 700; letter-spacing: .14em;
  text-transform: uppercase; color: var(--orange-600);
  padding: 6px 12px; border: 1px solid var(--line); border-radius: var(--r-pill);
  background: var(--cream-card);
}
.section--dark .eyebrow { color: var(--yellow); background: rgba(255,255,255,.05); border-color: rgba(255,255,255,.12); }
.accent { color: var(--orange-600); }
mark, .hl { background: linear-gradient(180deg, transparent 58%, rgba(244, 184, 46, .55) 58%); padding: 0 .1em; color: inherit; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-family: var(--font-body); font-weight: 700; font-size: 1rem;
  padding: 14px 26px; border-radius: var(--r-pill); border: 1.5px solid transparent;
  cursor: pointer; transition: transform .15s ease, background .2s ease, box-shadow .2s ease, color .2s ease;
  text-align: center; line-height: 1.2;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--orange); color: #fff; box-shadow: 0 10px 24px -10px rgba(244, 124, 48, .8); }
.btn-primary:hover { background: var(--orange-600); }
.btn-ink { background: var(--ink); color: var(--cream); }
.btn-ink:hover { background: #0f1620; }
.btn-ghost { background: transparent; border-color: var(--ink); color: var(--ink); }
.btn-ghost:hover { background: var(--ink); color: var(--cream); }
.section--dark .btn-ghost { border-color: rgba(245,239,217,.5); color: var(--cream); }
.section--dark .btn-ghost:hover { background: var(--cream); color: var(--ink); }
.btn-lg { padding: 16px 32px; font-size: 1.08rem; }
.btn-row { display: flex; flex-wrap: wrap; gap: 14px; }

/* ---------- Header / Nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(245, 239, 217, .82); backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav__inner { display: flex; align-items: center; gap: 18px; height: 66px; }
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--font-en); font-weight: 800; font-size: 1.05rem; letter-spacing: .02em; }
.brand svg, .brand img { width: 26px; height: auto; }
.nav__links { display: flex; gap: 22px; margin-left: auto; align-items: center; }
.nav__links a { font-size: .95rem; font-weight: 500; color: var(--ink-soft); }
.nav__links a:hover { color: var(--ink); }
.nav__cta { margin-left: 4px; }
.nav__burger { display: none; margin-left: auto; background: none; border: 0; font-size: 1.5rem; cursor: pointer; color: var(--ink); }

/* ---------- Hero ---------- */
.hero { padding-block: clamp(48px, 7vw, 92px); position: relative; overflow: hidden; }
.hero__grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(28px, 5vw, 64px); align-items: center; }
.hero h1 { margin-bottom: .35em; }
.hero .lead { margin-bottom: 1.6em; max-width: 36ch; }
.hero__badges { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 26px; }
.badge {
  display: inline-flex; align-items: center; gap: 8px; font-size: .85rem; font-weight: 600;
  padding: 8px 14px; border-radius: var(--r-pill); background: var(--cream-card);
  border: 1px solid var(--line); color: var(--ink-soft);
}
.badge::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: var(--green); }
.hero__art { display: flex; justify-content: center; }
.flask-wrap {
  width: min(360px, 80%); aspect-ratio: 1; border-radius: 50%;
  background: radial-gradient(circle at 50% 38%, #fff7e6, var(--cream) 70%);
  display: grid; place-items: center; box-shadow: var(--shadow-lg); border: 1px solid var(--line);
}
.flask-wrap svg, .flask-wrap img { width: 58%; height: auto; filter: drop-shadow(0 14px 24px rgba(244,124,48,.28)); }

/* ---------- Generic grids ---------- */
.grid { display: grid; gap: 22px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.section-head { max-width: 760px; margin-bottom: clamp(32px, 5vw, 52px); }
.section-head.center { margin-inline: auto; }
.section-head h2 { margin-top: .4em; }

/* ---------- Cards ---------- */
.card {
  background: var(--cream-card); border: 1px solid var(--line); border-radius: var(--r-lg);
  padding: 26px; box-shadow: var(--shadow);
}
.card h3 { margin-bottom: .35em; }
.card p { color: var(--ink-soft); margin-bottom: 0; }
.card--num { position: relative; }
.card__num { font-family: var(--font-en); font-size: 2.4rem; font-weight: 800; color: var(--green); line-height: 1; margin-bottom: 10px; }
.card__tag { font-size: .78rem; font-weight: 700; letter-spacing: .04em; color: var(--orange-600); text-transform: uppercase; }
.icon-dot { width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center; background: rgba(155,201,144,.28); font-size: 1.3rem; margin-bottom: 14px; }

/* feature list with check */
.checklist { list-style: none; padding: 0; margin: 0; display: grid; gap: 12px; }
.checklist li { position: relative; padding-left: 30px; color: var(--ink-soft); line-height: 1.55; }
.checklist li::before {
  content: "✓"; position: absolute; left: 0; top: 1px; width: 20px; height: 20px;
  background: var(--green); color: #16321a; border-radius: 50%; font-size: .75rem; font-weight: 800;
  display: grid; place-items: center;
}
.crosslist li::before { content: "✕"; background: #e9d6c2; color: #9a5a32; }

/* ---------- Compare (vs chatbot / tự mò) ---------- */
.compare { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.compare__col { border-radius: var(--r-lg); padding: 28px; border: 1px solid var(--line); }
.compare__col--bad { background: #f3ecda; }
.compare__col--good { background: var(--ink); color: var(--cream); border-color: var(--ink); box-shadow: var(--shadow-lg); }
.compare__col--good .checklist li { color: rgba(245,239,217,.86); }
.compare__col h3 { font-size: 1.15rem; }
.compare__col ul { margin-top: 16px; }
.compare__col--bad ul { list-style: none; padding: 0; display: grid; gap: 11px; }
.compare__col--bad li { position: relative; padding-left: 28px; color: var(--muted); }
.compare__col--bad li::before { content: "–"; position: absolute; left: 6px; font-weight: 800; color: #b08968; }

/* ---------- Chat mockup — dựng như một nhóm Telegram (OS demo) ----------
   AI agent sống trong một nhóm Telegram: thanh tiêu đề sáng, hình nền ấm có hoạ
   tiết, bong bóng nhận (trắng, tên người gửi có màu) + bong bóng gửi (xanh lá nhạt
   kèm ✓✓). Restyle thuần CSS nên áp cho cả 6 trang dùng chung class .chat/.bubble. */
.chat {
  position: relative; max-width: 460px; padding: 14px; border-radius: var(--r-lg);
  border: 1px solid var(--line); box-shadow: var(--shadow-lg); overflow: hidden; color: var(--ink);
  background-color: #e9ddc7;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='46' height='46'%3E%3Cg fill='none' stroke='%23b59a6c' stroke-width='1.3' stroke-linecap='round' opacity='0.45'%3E%3Ccircle cx='11' cy='12' r='4'/%3E%3Cpath d='M32 6v9M27.5 10.5h9'/%3E%3Ccircle cx='35' cy='34' r='2.3'/%3E%3Cpath d='M6 33l3.5-3.5M9.5 33L6 29.5'/%3E%3C/g%3E%3C/svg%3E");
}
/* thanh tiêu đề full-bleed (margin âm bù padding 14px của .chat) */
.chat__head {
  display: flex; align-items: center; gap: 11px;
  margin: -14px -14px 14px; padding: 11px 15px;
  background: #fff; border-bottom: 1px solid rgba(31, 41, 55, .08); box-shadow: 0 1px 6px rgba(31, 41, 55, .06);
}
.chat__head img {
  width: 40px !important; height: 40px !important; border-radius: 50%; padding: 5px;
  background: #fbf7ea; box-shadow: inset 0 0 0 1px rgba(31, 41, 55, .1);
}
.chat__head::after { content: "⋮"; margin-left: auto; color: #8a93a0; font-size: 1.3rem; line-height: 1; align-self: center; }
.chat__title { font-weight: 700; font-size: .95rem; color: var(--ink); line-height: 1.25; }
.chat__topics { font-size: .76rem; color: #4a7344; font-weight: 600; margin-top: 1px; }
.bubble {
  position: relative; width: fit-content; max-width: 84%;
  padding: 7px 11px 8px; border-radius: 13px; font-size: .9rem; line-height: 1.48; margin-bottom: 8px;
  box-shadow: 0 1px 1.5px rgba(31, 41, 55, .14);
}
.bubble--me { margin-left: auto; background: #eeffde; color: var(--ink); border-bottom-right-radius: 5px; padding-right: 30px; }
.bubble--me::after { content: "✓✓"; position: absolute; right: 9px; bottom: 5px; font-size: .62rem; letter-spacing: -1px; color: #3f8a45; }
.bubble--bot { background: #fff; color: var(--ink); border-bottom-left-radius: 5px; }
.bubble__who { display: block; font-size: .72rem; font-weight: 700; color: #b8541b; margin-bottom: 2px; }
.bubble--typing { background: #fff; color: var(--muted); font-style: italic; font-size: .82rem; }

/* topic tabs (chỉ trang có nhiều thread, vd Ultra): mỗi phòng ban một kênh, đổi qua lại */
.chat--tabbed .chat__head { box-shadow: none; border-bottom: none; margin-bottom: 0; }
.chat__tabs {
  display: flex; gap: 7px; flex-wrap: wrap; margin: 0 -14px 12px; padding: 9px 14px 11px;
  background: #fff; border-bottom: 1px solid rgba(31, 41, 55, .08); box-shadow: 0 2px 7px rgba(31, 41, 55, .05);
}
.chat__tab {
  font-family: var(--font-body); font-size: .78rem; font-weight: 600; color: var(--ink-soft);
  background: #efe8d8; border: 0; border-radius: var(--r-pill); padding: 6px 13px; cursor: pointer;
  transition: background .15s ease, color .15s ease;
}
.chat__tab:hover { background: #e5dcc6; }
.chat__tab.is-active { background: var(--orange); color: #fff; }
.chat__thread[hidden] { display: none; }
.chat__thread { animation: chatfade .28s ease; }
@keyframes chatfade { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: none; } }

/* ---------- Compounding steps (hiệu ứng cộng hưởng) ---------- */
.cycle { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; counter-reset: step; }
.cycle__item { text-align: center; padding: 22px 16px; border-radius: var(--r); background: var(--cream-card); border: 1px solid var(--line); position: relative; }
.cycle__n { width: 38px; height: 38px; border-radius: 50%; background: var(--orange); color: #fff; font-family: var(--font-en); font-weight: 800; display: grid; place-items: center; margin: 0 auto 12px; }
.cycle__item h4 { margin: 0 0 6px; font-size: 1.02rem; }
.cycle__item p { font-size: .9rem; color: var(--muted); margin: 0; }

/* ---------- Audience cards ---------- */
.who { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.who__card { background: var(--cream-card); border: 1px solid var(--line); border-radius: var(--r-lg); padding: 28px; }
.who__card .quote { font-style: italic; color: var(--ink-soft); border-left: 3px solid var(--orange); padding-left: 14px; margin: 14px 0; }
.who__pin { font-size: .72rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--green-700); }

/* ---------- Pricing ---------- */
.price-card {
  background: var(--cream-card); border: 1.5px solid var(--ink); border-radius: var(--r-lg);
  padding: clamp(28px, 4vw, 44px); max-width: 640px; margin-inline: auto; box-shadow: var(--shadow-lg);
}
.price-card__eyebrow { font-size: .82rem; font-weight: 700; color: var(--orange-600); letter-spacing: .06em; }
.price-card__name { font-family: var(--font-en); font-weight: 800; font-size: 1.1rem; letter-spacing: .06em; margin: 6px 0; }
.price-card__amount { font-size: clamp(2.9rem, 8vw, 4.2rem); font-weight: 800; line-height: 1; margin: 10px 0; color: var(--ink); }
.price-card__amount small { display: inline-block; margin-left: 6px; font-size: .92rem; font-weight: 600; color: var(--muted); letter-spacing: 0; }
.price-card .checklist { margin: 22px 0 26px; }
.price-note { font-size: .86rem; color: var(--muted); margin-top: 16px; }

/* full value stack trong price-card (gói cao: liệt kê đầy đủ theo nhóm) */
.price-feats { margin: 20px 0 8px; }
.price-feats__group {
  font-size: .98rem; font-weight: 800; color: var(--ink); letter-spacing: -.01em;
  margin: 20px 0 12px; padding-top: 16px; border-top: 1px solid var(--line);
}
.price-feats__group:first-child { margin-top: 4px; padding-top: 0; border-top: none; }
.price-feats .checklist { margin: 0; gap: 11px; }
.price-feats .checklist li { font-size: .95rem; }

/* pricing tiers grid (home) */
.tiers { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.tier {
  background: var(--cream-card); border: 1px solid var(--line); border-radius: var(--r-lg);
  padding: 26px; display: flex; flex-direction: column; box-shadow: var(--shadow);
  transition: transform .18s ease, box-shadow .2s ease;
}
.tier:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.tier--feature { border-color: var(--orange); border-width: 1.5px; }
.tier__ribbon { font-size: .72rem; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; color: var(--orange-600); margin-bottom: 8px; min-height: 1em; }
.tier__name { font-family: var(--font-en); font-weight: 800; font-size: 1.25rem; }
.tier__price { font-size: 1.7rem; font-weight: 800; margin: 8px 0 2px; }
.tier__price small { font-size: .85rem; font-weight: 600; color: var(--muted); }
.tier p { font-size: .94rem; color: var(--ink-soft); flex: 1; }
.tier .btn { margin-top: 16px; width: 100%; }
.tier--soon { opacity: .82; }
.tag-soon { display: inline-block; font-size: .7rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--green-700); background: rgba(155,201,144,.3); padding: 3px 9px; border-radius: var(--r-pill); }

/* ---------- FAQ ---------- */
.faq { max-width: 800px; margin-inline: auto; display: grid; gap: 12px; }
.faq details { background: var(--cream-card); border: 1px solid var(--line); border-radius: var(--r); padding: 4px 20px; }
.faq summary { font-weight: 700; cursor: pointer; padding: 16px 0; list-style: none; display: flex; justify-content: space-between; gap: 16px; align-items: center; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-size: 1.5rem; color: var(--orange-600); font-weight: 400; transition: transform .2s; }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { color: var(--ink-soft); padding-bottom: 18px; margin: 0; }

/* ---------- Checkout panel + <sds-checkout> ---------- */
.buybox { background: var(--cream-card); border: 1px solid var(--line); border-radius: var(--r-lg); padding: 24px; box-shadow: var(--shadow); }
.buybox__price { font-size: 2rem; font-weight: 800; }
.buybox__price small { font-size: .95rem; font-weight: 600; color: var(--muted); }
.buybox__note { font-size: .82rem; color: var(--muted); margin-top: 14px; }

sds-checkout { display: block; margin-top: 16px; }
sds-checkout .sds-form { display: flex; flex-direction: column; gap: 10px; }
sds-checkout input {
  width: 100%; padding: 13px 15px; border: 1.5px solid var(--line); border-radius: var(--r);
  font-size: 1rem; font-family: var(--font-body); background: #fff; color: var(--ink);
}
sds-checkout input:focus { outline: none; border-color: var(--orange); }
sds-checkout .sds-buy {
  width: 100%; padding: 14px; background: var(--orange); color: #fff; border: 0; border-radius: var(--r-pill);
  font-family: var(--font-body); font-weight: 700; font-size: 1.02rem; cursor: pointer;
  transition: background .2s ease, transform .15s ease;
}
sds-checkout .sds-buy:hover { background: var(--orange-600); transform: translateY(-1px); }
sds-checkout .sds-buy:disabled { opacity: .6; cursor: progress; transform: none; }
sds-checkout .sds-error { color: #c0392b; font-size: .86rem; }
sds-checkout .sds-payment { text-align: center; }
sds-checkout .sds-qr { display: block; margin: 14px auto; border: 1px solid var(--line); border-radius: var(--r); background: #fff; }
sds-checkout .sds-manual { font-size: .86rem; color: var(--ink-soft); background: #fff; border: 1px dashed var(--line); border-radius: var(--r); padding: 12px; text-align: left; }
sds-checkout .sds-status { font-weight: 700; color: var(--orange-600); margin-top: 12px; }
sds-checkout .sds-final { text-align: center; padding: 8px 0; }
sds-checkout .sds-final h3 { margin-bottom: 6px; }
sds-checkout .sds-final.sds-ok h3 { color: var(--green-700); }
sds-checkout .sds-final.sds-fail h3 { color: #c0392b; }

/* ---------- Buy layout: pricing card + đăng-ký form song song ---------- */
.buy-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: clamp(20px, 3vw, 36px);
  align-items: start; max-width: 1000px; margin-inline: auto;
}
.buy-grid .price-card { max-width: none; margin: 0; }

.buy-panel {
  background: var(--dark); color: var(--cream); border-radius: var(--r-lg);
  padding: clamp(24px, 3vw, 38px); box-shadow: var(--shadow-lg);
  border: 1px solid rgba(255, 255, 255, .06);
}
.buyform__badge {
  display: inline-flex; align-items: center; gap: 7px; font-size: .74rem; font-weight: 700;
  letter-spacing: .1em; text-transform: uppercase; color: var(--yellow);
  background: rgba(255, 255, 255, .06); border: 1px solid rgba(255, 255, 255, .12);
  padding: 6px 13px; border-radius: var(--r-pill); margin-bottom: 16px;
}
.buyform__title { font-size: clamp(1.3rem, 2.4vw, 1.7rem); color: var(--cream); margin: 0 0 8px; }
.buyform__sub { font-size: .95rem; color: rgba(245, 239, 217, .72); margin: 0 0 22px; line-height: 1.55; }
.buyform__sub strong { color: var(--cream); }

.field { margin-bottom: 16px; }
.field > label { display: block; font-size: .9rem; font-weight: 600; color: rgba(245, 239, 217, .9); margin-bottom: 7px; }
.field .req { color: var(--orange); }
.field .opt { color: rgba(245, 239, 217, .5); font-weight: 500; }
.buyform input[type="text"], .buyform input[type="email"], .buyform input[type="tel"] {
  width: 100%; padding: 13px 15px; font-size: 1rem; font-family: var(--font-body);
  color: var(--cream); background: rgba(255, 255, 255, .04);
  border: 1.5px solid rgba(255, 255, 255, .14); border-radius: var(--r);
}
.buyform input::placeholder { color: rgba(245, 239, 217, .5); }
.buyform input:focus { outline: none; border-color: var(--orange); background: rgba(255, 255, 255, .07); }
.field__hint { font-size: .8rem; color: rgba(245, 239, 217, .55); margin: 7px 0 0; line-height: 1.5; }

.checkbox {
  display: flex; gap: 11px; align-items: flex-start; padding: 14px; margin: 4px 0 20px;
  background: rgba(255, 255, 255, .03); border: 1px solid rgba(255, 255, 255, .1);
  border-radius: var(--r); cursor: pointer;
}
.checkbox input { margin-top: 3px; width: 18px; height: 18px; accent-color: var(--orange); flex: none; }
.checkbox span { font-size: .82rem; color: rgba(245, 239, 217, .6); line-height: 1.5; }
.checkbox strong { color: rgba(245, 239, 217, .92); font-weight: 600; }

.buyform__submit {
  width: 100%; padding: 16px; background: var(--orange); color: #fff; border: 0;
  border-radius: var(--r-pill); font-family: var(--font-body); font-weight: 700; font-size: 1.05rem;
  cursor: pointer; transition: background .2s ease, transform .15s ease;
  box-shadow: 0 12px 26px -10px rgba(244, 124, 48, .7);
}
.buyform__submit:hover { background: var(--orange-600); transform: translateY(-2px); }
.buyform__submit:disabled { opacity: .6; cursor: progress; transform: none; }
.buyform__error { color: #ffb4a2; font-size: .88rem; margin: 12px 0 0; }
.buyform__secure { font-size: .8rem; color: rgba(245, 239, 217, .5); text-align: center; margin: 14px 0 0; }

/* payment (QR) view rendered in place of the form after "Thanh toán" */
.buy-pay { text-align: center; }
.buy-pay__amount { font-size: 1.08rem; color: rgba(245, 239, 217, .85); margin: 0 0 14px; }
.buy-pay__amount strong { color: var(--cream); }
.buy-pay__qr { width: 240px; height: 240px; margin: 0 auto 16px; background: #fff; border-radius: var(--r); padding: 8px; }
.buy-pay__manual {
  text-align: left; font-size: .88rem; color: rgba(245, 239, 217, .75);
  background: rgba(255, 255, 255, .04); border: 1px dashed rgba(255, 255, 255, .18);
  border-radius: var(--r); padding: 14px; margin: 0 0 14px;
}
.buy-pay__manual summary { cursor: pointer; font-weight: 600; color: var(--cream); }
.buy-pay__manual ul { list-style: none; padding: 0; margin: 12px 0 0; display: grid; gap: 7px; }
.buy-pay__manual strong { color: var(--cream); }
.buy-pay__status { font-weight: 700; color: var(--yellow); margin: 8px 0 0; }
.buy-pay__status--ok { color: var(--green); }
.buy-pay__status--bad { color: #ffb4a2; }

/* panel "gửi cho kế toán" (khi khách cần xuất hóa đơn) */
.buy-acct { background: rgba(244, 124, 48, .1); border: 1px solid rgba(244, 124, 48, .45); border-radius: var(--r); padding: 16px; margin-bottom: 18px; text-align: left; }
.buy-acct h3 { color: var(--cream); font-size: 1.02rem; margin: 0 0 8px; }
.buy-acct p { color: rgba(245, 239, 217, .72); font-size: .85rem; margin: 0 0 10px; line-height: 1.5; }
.buy-acct__link { display: block; word-break: break-all; color: var(--yellow); font-size: .82rem; margin-bottom: 10px; }
.buy-acct__msg { width: 100%; height: 104px; resize: vertical; background: rgba(0, 0, 0, .25); color: rgba(245, 239, 217, .88); border: 1px solid rgba(255, 255, 255, .14); border-radius: 10px; padding: 10px; font-size: .8rem; font-family: var(--font-body); margin-bottom: 10px; }
.buy-acct__copy { width: 100%; padding: 11px; background: #fff; color: var(--ink); border: 0; border-radius: var(--r-pill); font-weight: 700; cursor: pointer; font-family: var(--font-body); }
.buy-acct__copy:hover { background: var(--cream); }

@media (max-width: 880px) {
  .buy-grid { grid-template-columns: 1fr; max-width: 560px; }
}

/* ---------- Hiệu ứng cộng hưởng (resonance) ---------- */
.resonance .section-head { max-width: 840px; }
.hot { color: var(--yellow); }

.rflow { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; position: relative; margin-top: 10px; }
.rflow__step {
  background: rgba(255, 255, 255, .05); border: 1px solid rgba(255, 255, 255, .1);
  border-radius: var(--r-lg); padding: 22px 18px; position: relative;
}
.rflow__icon { width: 46px; height: 46px; border-radius: 13px; background: var(--orange); display: grid; place-items: center; margin-bottom: 14px; box-shadow: 0 8px 18px -8px rgba(244, 124, 48, .8); }
.rflow__icon svg { width: 24px; height: 24px; }
.rflow__step h4 { color: var(--cream); margin: 0 0 7px; font-size: 1.06rem; }
.rflow__n { color: var(--yellow); font-family: var(--font-en); margin-right: 3px; }
.rflow__step p { color: rgba(245, 239, 217, .72); font-size: .92rem; margin: 0; line-height: 1.5; }
.rflow__step:not(:last-child)::after {
  content: "→"; position: absolute; right: -13px; top: 50%; transform: translateY(-50%);
  color: rgba(245, 239, 217, .4); font-size: 1.3rem; z-index: 2;
}

.rgrid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 24px; align-items: center; margin-top: 30px; }
.rchart { background: rgba(255, 255, 255, .04); border: 1px solid rgba(255, 255, 255, .1); border-radius: var(--r-lg); padding: 18px 20px; }
.rchart svg { width: 100%; height: auto; display: block; }
.rcompare { display: grid; gap: 16px; }
.rcompare__item {
  display: flex; gap: 14px; align-items: flex-start;
  background: rgba(255, 255, 255, .04); border: 1px solid rgba(255, 255, 255, .1);
  border-radius: var(--r-lg); padding: 18px;
}
.rcompare__icon { width: 42px; height: 42px; border-radius: 12px; flex: none; display: grid; place-items: center; }
.rcompare__icon svg { width: 22px; height: 22px; }
.rcompare__icon--up { background: rgba(155, 201, 144, .2); }
.rcompare__icon--down { background: rgba(255, 255, 255, .07); }
.rcompare__item h4 { color: var(--cream); margin: 0 0 5px; font-size: 1.06rem; }
.rcompare__item p { color: rgba(245, 239, 217, .72); font-size: .9rem; margin: 0; line-height: 1.5; }

.rcta {
  margin-top: 34px; text-align: center; background: rgba(244, 124, 48, .08);
  border: 1.5px solid rgba(244, 124, 48, .5); border-radius: var(--r-lg);
  padding: 30px clamp(20px, 4vw, 44px);
}
.rcta p { color: var(--cream); font-size: 1.18rem; font-weight: 600; max-width: 60ch; margin: 0 auto 20px; line-height: 1.5; }

@media (max-width: 860px) {
  .rflow { grid-template-columns: repeat(2, 1fr); }
  .rflow__step:not(:last-child)::after { display: none; }
  .rgrid { grid-template-columns: 1fr; }
}
@media (max-width: 460px) { .rflow { grid-template-columns: 1fr; } }

/* ---------- Banner / CTA strip ---------- */
.cta-strip { text-align: center; }
.cta-strip h2 { max-width: 16ch; margin-inline: auto; }
.cta-strip .lead { max-width: 56ch; margin: 0 auto 1.6em; }

/* ---------- Footer ---------- */
.footer { background: var(--dark); color: rgba(245,239,217,.72); padding-block: 52px 36px; }
.footer__top { display: flex; flex-wrap: wrap; gap: 32px; justify-content: space-between; }
.footer .brand { color: var(--cream); margin-bottom: 12px; }
.footer__links { display: flex; flex-wrap: wrap; gap: 28px; }
.footer__col h4 { font-size: .82rem; letter-spacing: .08em; text-transform: uppercase; color: var(--yellow); margin-bottom: 12px; }
.footer__col a { display: block; font-size: .92rem; padding: 4px 0; color: rgba(245,239,217,.72); }
.footer__col a:hover { color: var(--cream); }
.footer__bottom { border-top: 1px solid rgba(255,255,255,.1); margin-top: 32px; padding-top: 20px; font-size: .82rem; color: rgba(245,239,217,.5); display: flex; flex-wrap: wrap; gap: 12px; justify-content: space-between; }

/* ---------- Utilities ---------- */
.stack > * + * { margin-top: 1rem; }
.mt-0 { margin-top: 0; } .mb-0 { margin-bottom: 0; }
.divider { height: 1px; background: var(--line); border: 0; margin: 0; }

/* ---------- Contrast hardening ----------
   Light cream cards must keep DARK text even when nested inside a .section--dark.
   Otherwise headings (which carry no explicit color) inherit the section's light
   --cream color and turn pale-on-pale. Paragraphs were unaffected (explicit color). */
.card, .tier, .cycle__item, .who__card, .price-card, .buybox,
.compare__col--bad, .faq details { color: var(--ink); }
.card h3, .card h4, .tier__name, .tier__price,
.cycle__item h4, .who__card h3, .price-card__name { color: var(--ink); }
/* ghost buttons sitting on light cards inside dark sections → dark text, not cream */
.section--dark .tier .btn-ghost,
.section--dark .card .btn-ghost { color: var(--ink); border-color: var(--ink); }
.section--dark .tier .btn-ghost:hover,
.section--dark .card .btn-ghost:hover { background: var(--ink); color: var(--cream); }

/* ---------- Responsive ---------- */
@media (max-width: 920px) {
  .hero__grid { grid-template-columns: 1fr; }
  .hero__art { order: -1; }
  .flask-wrap { width: min(240px, 60%); }
  .grid-3, .tiers, .cycle { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 680px) {
  body { font-size: 16px; }
  .nav__links { display: none; }
  .nav__links.open {
    display: flex; flex-direction: column; position: absolute; top: 66px; left: 0; right: 0;
    background: var(--cream); border-bottom: 1px solid var(--line); padding: 16px 20px; gap: 14px;
  }
  .nav__links.open .nav__cta { width: 100%; }
  .nav__burger { display: block; }
  .grid-2, .grid-3, .tiers, .compare, .who, .cycle { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto; animation: none !important; transition: none !important; } }