/* ORIGO — website tĩnh, hướng "kế toán + công nghệ".
   Token theo skills/origo-thiet-ke-an-pham/references/he-thong-thiet-ke.md.
   Tham chiếu phong cách: nền tối kỹ thuật + nhãn mono (kiểu david-hckh.com), khối sáng trình bày sản phẩm thật dạng bento (kiểu mobbin.com). */
/* Font tự lưu: assets/fonts/fonts.css (nạp trong _khung.html trước file này) */

:root {
  --navy: #0B3C5D; --navy-dam: #072A42; --navy-sau: #041B2B; --den-xanh: #050D16;
  --xanh-sang: #5FE3C4; --xanh-duong: #2A7FD5;
  --teal: #1F8A70; --teal-nhat: #7FD1BE; --vang: #D4AF37;
  --kem: #F7F9FB; --muc: #1B1F23; --thep: #5B6B7A; --suong: #DCE4EA; --trang: #FFFFFF;
  --font: 'Be Vietnam Pro', Montserrat, Arial, sans-serif;
  --mono: 'JetBrains Mono', 'SF Mono', Consolas, monospace;
  --container: 1240px; --gutter: 24px;
  --khoi: clamp(72px, 9vw, 136px);
  --line-toi: rgba(255,255,255,0.09);
  --line-sang: var(--suong);
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { font-family: var(--font); color: var(--muc); background: var(--kem); line-height: 1.6; font-size: 17px; -webkit-font-smoothing: antialiased; }
img, svg { max-width: 100%; display: block; }
a { color: var(--teal); text-decoration: none; }
a:hover { color: var(--navy); text-decoration: underline; text-underline-offset: 3px; }
h1, h2, h3, h4 { font-weight: 800; line-height: 1.06; letter-spacing: -0.025em; color: var(--navy); text-wrap: balance; }
h1 { font-size: clamp(40px, 6.4vw, 88px); }
h2 { font-size: clamp(30px, 4vw, 52px); }
h3 { font-size: clamp(20px, 2vw, 24px); letter-spacing: -0.01em; line-height: 1.2; }
p { text-wrap: pretty; }
.container { width: min(var(--container), 100% - 2 * var(--gutter)); margin-inline: auto; }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; transition: none !important; } }

/* Nhãn mono kỹ thuật */
.mono, .nhan { font-family: var(--mono); font-size: 12.5px; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; }
.nhan { color: var(--teal); display: inline-flex; align-items: center; gap: 12px; }
.nhan::before { content: ''; width: 24px; height: 2px; background: var(--teal); }
.toi .nhan { color: var(--teal-nhat); } .toi .nhan::before { background: var(--vang); }
.dan { font-size: clamp(18px, 1.5vw, 21px); color: var(--thep); max-width: 58ch; line-height: 1.55; }
.toi .dan { color: rgba(255,255,255,0.72); }

/* Nút */
.nut { display: inline-flex; align-items: center; gap: 10px; padding: 14px 24px; border-radius: 6px; font-weight: 700; background: var(--teal); color: var(--trang); border: 1.5px solid var(--teal); white-space: nowrap; min-height: 48px; transition: background .2s, border-color .2s, transform .2s; }
.nut:hover { background: var(--navy); border-color: var(--navy); color: var(--trang); text-decoration: none; transform: translateY(-1px); }
.nut.phu { background: transparent; color: var(--navy); border-color: var(--suong); }
.nut.phu:hover { border-color: var(--navy); background: var(--trang); color: var(--navy); }
.toi .nut { background: var(--vang); border-color: var(--vang); color: var(--navy-sau); }
.toi .nut:hover { background: var(--trang); border-color: var(--trang); color: var(--navy-sau); }
.toi .nut.phu { background: transparent; border-color: rgba(255,255,255,0.28); color: var(--trang); }
.toi .nut.phu:hover { border-color: var(--trang); background: rgba(255,255,255,0.06); color: var(--trang); }
.nut:focus-visible, a:focus-visible, button:focus-visible { outline: 2px solid var(--vang); outline-offset: 3px; }

/* Khối */
.khoi { padding-block: var(--khoi); }
.khoi.toi { background: var(--navy-dam); color: var(--trang); position: relative; }
.khoi.toi.sau { background: radial-gradient(ellipse 50% 60% at 85% 20%, rgba(31,138,112,0.22), transparent 70%), var(--navy-sau); }
.khoi.toi h2, .khoi.toi h3 { color: var(--trang); }
.khoi.toi a { color: var(--teal-nhat); }
.dau-khoi { display: grid; gap: 18px; margin-bottom: clamp(36px, 4vw, 64px); max-width: 820px; }
.dau-khoi.hai { grid-template-columns: minmax(0, 1fr) auto; align-items: end; max-width: none; }

/* Header tối, dính */
.header { position: sticky; top: 0; z-index: 50; background: rgba(5,13,22,0.8); backdrop-filter: blur(12px); border-bottom: 1px solid var(--line-toi); }
.header .container { display: flex; align-items: center; justify-content: space-between; gap: 24px; min-height: 68px; }
.logo { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; letter-spacing: 0.1em; color: var(--trang); font-size: 19px; }
.logo svg { width: 32px; height: 32px; }

.logo:hover { text-decoration: none; color: var(--trang); }
.nav { display: flex; align-items: center; gap: 26px; }
.nav a { color: rgba(255,255,255,0.78); font-weight: 500; font-size: 14.5px; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--trang); text-decoration: none; box-shadow: inset 0 -2px 0 var(--vang); }
.nav .nut { padding: 9px 16px; min-height: 40px; font-size: 14px; background: var(--vang); border-color: var(--vang); color: var(--navy-sau); }
.nav .nut:hover { background: var(--trang); border-color: var(--trang); }
.nav-toggle { display: none; background: none; border: 1px solid var(--line-toi); border-radius: 6px; width: 44px; height: 44px; align-items: center; justify-content: center; cursor: pointer; }
.nav-toggle svg { width: 22px; height: 22px; stroke: var(--trang); }

/* Hero tối: quầng sáng, lưới, sàn chấm 3D, khối cầu hologram */
.hero { position: relative; background: var(--den-xanh); color: var(--trang); overflow: hidden; padding-block: clamp(80px, 11vw, 150px) clamp(72px, 9vw, 128px); isolation: isolate; }
.hero .quang { position: absolute; inset: 0; pointer-events: none; z-index: 0;
  background:
    radial-gradient(ellipse 42% 55% at 78% 30%, rgba(31,138,112,0.38), transparent 70%),
    radial-gradient(ellipse 36% 46% at 12% 82%, rgba(42,127,213,0.22), transparent 70%),
    radial-gradient(ellipse 60% 40% at 50% 110%, rgba(7,42,66,0.9), transparent 70%); }
.hero .luoi { position: absolute; inset: 0; pointer-events: none; z-index: 0; background-image: linear-gradient(rgba(255,255,255,0.07) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,0.07) 1px, transparent 1px); background-size: 72px 72px; mask-image: radial-gradient(ellipse 70% 60% at 55% 40%, #000 20%, transparent 100%); }
.hero .san { position: absolute; left: -10%; right: -10%; bottom: -8%; height: 46%; pointer-events: none; z-index: 0; background: radial-gradient(circle, rgba(95,227,196,0.55) 1.2px, transparent 2px) 0 0 / 26px 26px; transform: perspective(700px) rotateX(64deg); transform-origin: 50% 100%; mask-image: linear-gradient(to top, rgba(0,0,0,0.9), transparent 85%); opacity: 0.7; }
.hero canvas.cau { position: absolute; right: -6%; top: -8%; width: min(64vw, 820px); height: min(64vw, 820px); pointer-events: none; z-index: 0; opacity: 0.9; }
.hero-phai { position: relative; min-height: 620px; }
.hero .khoi-3d { position: absolute; right: -28%; top: -30%; width: 138%; aspect-ratio: 1; pointer-events: none; z-index: 0; }
.hero .bang { position: absolute; left: -10%; bottom: -3%; width: 70%; z-index: 1; transform: perspective(1000px) rotateY(-5deg) rotateX(2deg); }
.hero canvas.cau { display: none; }
.hero .khoi-3d canvas { width: 100% !important; height: 100% !important; display: block; }
/* Thẻ nghiêng 3D (được JS gắn class .nghieng) */
.nghieng { transform-style: preserve-3d; transition: transform .25s ease, border-color .2s, box-shadow .25s; will-change: transform; }
.nghieng::after { content: ''; position: absolute; inset: 0; border-radius: inherit; background: radial-gradient(circle at var(--gx, 50%) var(--gy, 50%), rgba(255,255,255,0.18), transparent 55%); opacity: 0; transition: opacity .25s; pointer-events: none; }
.nghieng:hover::after { opacity: 1; }
.bento .o.nghieng, .khoa-hoc article.nghieng { position: relative; overflow: hidden; }
.bento .o.toi.nghieng::after { background: radial-gradient(circle at var(--gx, 50%) var(--gy, 50%), rgba(95,227,196,0.22), transparent 55%); }
.hero .container { position: relative; z-index: 1; display: grid; grid-template-columns: minmax(0, 6.6fr) minmax(0, 5.4fr); gap: clamp(40px, 6vw, 96px); align-items: center; }
.hero-chu { display: grid; gap: 26px; }
.hero-chu > * { animation: len .8s cubic-bezier(.2,.7,.2,1) both; }
.hero-chu > *:nth-child(2) { animation-delay: .06s } .hero-chu > *:nth-child(3) { animation-delay: .12s } .hero-chu > *:nth-child(4) { animation-delay: .18s } .hero-chu > *:nth-child(5) { animation-delay: .24s }
@keyframes len { from { transform: translateY(14px); } to { transform: translateY(0); } }
.hero-chu h1 { color: var(--trang); text-shadow: 0 2px 40px rgba(0,0,0,0.4); }
.hero-chu h1 em { font-style: normal; color: var(--xanh-sang); background: linear-gradient(100deg, #9FF0DC, #5FE3C4 40%, #D4AF37 110%); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero .dan { color: rgba(255,255,255,0.74); }
.hero-nut { display: flex; flex-wrap: wrap; gap: 12px; }
.hero-ghi { font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.04em; color: rgba(255,255,255,0.5); }
.hero-index { display: flex; flex-wrap: wrap; gap: 10px 28px; font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--xanh-sang); }
.hero-index span::before { content: attr(data-so) '  '; color: rgba(255,255,255,0.4); }
.hero .nut { background: var(--xanh-sang); border-color: var(--xanh-sang); color: var(--den-xanh); box-shadow: 0 0 0 0 rgba(95,227,196,0); }
.hero .nut:hover { background: var(--trang); border-color: var(--trang); color: var(--den-xanh); box-shadow: 0 0 40px -6px rgba(95,227,196,0.6); }
.hero .nut.phu { background: rgba(255,255,255,0.04); border-color: rgba(255,255,255,0.22); color: var(--trang); backdrop-filter: blur(6px); }
.hero .nut.phu:hover { border-color: var(--trang); background: rgba(255,255,255,0.08); box-shadow: none; }

/* Bảng điều khiển (minh hoạ báo cáo tháng) */
.bang { background: rgba(5,13,22,0.55); border: 1px solid rgba(127,209,190,0.22); border-radius: 12px; overflow: hidden; box-shadow: 0 0 0 1px rgba(95,227,196,0.06), 0 30px 90px -30px rgba(31,138,112,0.45), 0 40px 80px -40px rgba(0,0,0,0.7); backdrop-filter: blur(14px); position: relative; }
.hero .bang::before { content: ''; position: absolute; inset: 0; border-radius: inherit; background: linear-gradient(135deg, rgba(255,255,255,0.08), transparent 40%, transparent 60%, rgba(95,227,196,0.06)); pointer-events: none; }
.bang header { display: flex; justify-content: space-between; align-items: center; padding: 14px 20px; border-bottom: 1px solid var(--line-toi); font-family: var(--mono); font-size: 12px; letter-spacing: 0.06em; text-transform: uppercase; color: rgba(255,255,255,0.6); }
.bang header b { color: var(--trang); font-weight: 600; }
.bang .dong { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 16px; align-items: center; padding: 13px 20px; border-bottom: 1px solid var(--line-toi); font-size: 14.5px; color: rgba(255,255,255,0.86); }
.bang .dong:last-of-type { border-bottom: 0; }
.bang .chip { font-family: var(--mono); font-size: 12px; font-weight: 500; letter-spacing: 0.04em; padding: 4px 10px; border-radius: 4px; border: 1px solid transparent; white-space: nowrap; }
.chip.ok { color: var(--xanh-sang); border-color: rgba(127,209,190,0.35); background: rgba(31,138,112,0.14); }
.chip.chu-y { color: var(--vang); border-color: rgba(212,175,55,0.4); background: rgba(212,175,55,0.1); }
.chip.trung { color: rgba(255,255,255,0.8); border-color: var(--line-toi); }
.bang .thanh { padding: 14px 20px 18px; border-top: 1px solid var(--line-toi); display: grid; gap: 8px; font-family: var(--mono); font-size: 12px; color: rgba(255,255,255,0.6); letter-spacing: 0.04em; }
.bang .thanh i { display: block; height: 6px; border-radius: 3px; background: rgba(255,255,255,0.08); overflow: hidden; }
.bang .thanh i::after { content: ''; display: block; height: 100%; width: 92%; background: linear-gradient(90deg, var(--teal), var(--xanh-sang)); box-shadow: 0 0 12px rgba(95,227,196,0.6); }
.bang footer { padding: 10px 20px; font-size: 12px; color: rgba(255,255,255,0.45); border-top: 1px solid var(--line-toi); }

/* Ba trụ cột: dải index */
.tru-cot { border-top: 1px solid var(--suong); border-bottom: 1px solid var(--suong); background: var(--trang); }
.tru-cot .container { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.tru-cot a { display: grid; gap: 12px; grid-template-columns: auto minmax(0, 1fr); grid-template-rows: auto auto auto; column-gap: 16px; padding: 32px 28px 32px 0; color: var(--muc); border-right: 1px solid var(--suong); }
.tru-cot a + a { padding-left: 28px; }
.tru-cot a:last-child { border-right: 0; }
.tru-cot a:hover { text-decoration: none; }
.tru-cot a:hover b { color: var(--teal); }
.tru-cot a b::after { content: ' →'; opacity: 0; transition: opacity .2s; }
.tru-cot a:hover b::after { opacity: 1; }
.tru-cot .ic { grid-row: 1 / 4; margin-top: 4px; }
.tru-cot .mono { color: var(--thep); }
.tru-cot b { font-size: 22px; font-weight: 700; color: var(--navy); letter-spacing: -0.01em; transition: color .2s; }
.tru-cot small { color: var(--thep); font-size: 15px; }

/* Icon nét mảnh */
.ic { width: 28px; height: 28px; stroke: var(--teal); fill: none; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.toi .ic, .o.toi .ic { stroke: var(--xanh-sang); }
.tru-cot .ic { width: 26px; height: 26px; }

/* Bento dịch vụ */
.bento { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 16px; }
.bento .o { grid-column: span 2; background: var(--trang); border: 1px solid var(--suong); border-radius: 16px; padding: 28px; display: grid; gap: 12px; align-content: start; color: var(--muc); position: relative; transition: border-color .2s, transform .2s; }
.bento .o:hover { border-color: var(--teal); transform: translateY(-2px); text-decoration: none; box-shadow: 0 20px 40px -28px rgba(11,60,93,0.35); }
.bento .o:hover .di { color: var(--navy); }
.bento .o.rong { grid-column: span 4; }
.bento .o.vua { grid-column: span 3; }
.bento .o.lon { grid-column: span 4; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 28px; align-items: center; }
.bento .o.lon > div { display: grid; gap: 12px; }
.bento .o .dau-o { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.bento .o .mono { color: var(--thep); }
.bento .o h3 { color: var(--navy); }
.bento .o p { color: var(--thep); font-size: 15.5px; }
.bento .o .di { font-family: var(--mono); font-size: 12.5px; color: var(--teal); letter-spacing: 0.06em; text-transform: uppercase; margin-top: auto; }
.bento .o.toi { background: var(--navy); border-color: var(--navy); color: var(--trang); }
.bento .o.toi h3 { color: var(--trang); } .bento .o.toi p { color: rgba(255,255,255,0.72); } .bento .o.toi .mono { color: var(--teal-nhat); } .bento .o.toi .di { color: var(--vang); }
/* mô phỏng nhỏ trong ô lớn */
.mo-phong { background: var(--kem); border: 1px solid var(--suong); border-radius: 8px; padding: 16px; display: grid; gap: 8px; font-family: var(--mono); font-size: 12.5px; color: var(--thep); }
.mo-phong div { display: flex; justify-content: space-between; gap: 12px; padding: 6px 0; border-bottom: 1px dashed var(--suong); }
.mo-phong div:last-child { border-bottom: 0; }
.mo-phong b { color: var(--navy); font-weight: 600; }
.mo-phong .ok { color: var(--teal); } .mo-phong .chu-y { color: #B26A00; }

/* Quy trình dạng dòng thời gian */
.buoc { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 24px; position: relative; counter-reset: b; }
.buoc::before { display: none; }
.buoc div { position: relative; padding: 28px 22px 24px; display: grid; gap: 10px; background: rgba(255,255,255,0.035); border: 1px solid var(--line-toi); border-radius: 16px; backdrop-filter: blur(6px); transition: border-color .2s, transform .2s; }
.buoc div:hover { border-color: rgba(95,227,196,0.45); transform: translateY(-3px); }
.buoc div::before { counter-increment: b; content: '0' counter(b); position: absolute; top: -12px; left: 18px; font-family: var(--mono); font-size: 12px; letter-spacing: 0.08em; color: var(--den-xanh); background: var(--xanh-sang); padding: 3px 10px; border-radius: 999px; font-weight: 600; }
.buoc div::after { display: none; }
.buoc h3 { font-size: 20px; }
.buoc p { font-size: 15px; color: rgba(255,255,255,0.7); }

/* Khối "terminal" đối soát */
.terminal { background: var(--den-xanh); border: 1px solid rgba(127,209,190,0.2); box-shadow: 0 30px 80px -40px rgba(31,138,112,0.5); border-radius: 10px; font-family: var(--mono); font-size: 13.5px; line-height: 1.75; color: rgba(255,255,255,0.85); overflow: hidden; }
.terminal header { padding: 10px 18px; border-bottom: 1px solid var(--line-toi); font-size: 11.5px; letter-spacing: 0.08em; text-transform: uppercase; color: rgba(255,255,255,0.45); display: flex; justify-content: space-between; }
.terminal pre { padding: 18px 20px; white-space: pre-wrap; margin: 0; font: inherit; }
.terminal .lenh { color: var(--trang); }
.terminal .ok { color: var(--xanh-sang); } .terminal .canh { color: var(--vang); } .terminal .mo { color: rgba(255,255,255,0.45); }
.cong-nghe { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: clamp(32px, 5vw, 72px); align-items: center; }
.cong-nghe ul { list-style: none; display: grid; gap: 22px; }
.cong-nghe li { display: grid; gap: 6px; padding-left: 22px; position: relative; }
.cong-nghe li::before { content: ''; position: absolute; left: 0; top: 10px; width: 8px; height: 8px; border-radius: 50%; background: var(--teal-nhat); }
.cong-nghe li b { font-size: 18px; font-weight: 700; color: var(--trang); }
.cong-nghe li span { color: rgba(255,255,255,0.7); font-size: 15.5px; }

/* Khóa học */
.khoa-hoc { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.khoa-hoc article { background: var(--trang); border: 1px solid var(--suong); border-radius: 16px; padding: 28px; display: grid; gap: 14px; align-content: start; transition: border-color .2s, transform .2s, box-shadow .2s; }
.khoa-hoc article:hover { border-color: var(--teal); transform: translateY(-2px); box-shadow: 0 20px 40px -28px rgba(11,60,93,0.35); }
.khoa-hoc .mono { color: var(--thep); }
.khoa-hoc h3 { color: var(--navy); }
.khoa-hoc p { color: var(--thep); font-size: 15.5px; }
.khoa-hoc dl { display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 6px 14px; font-size: 14px; border-top: 1px solid var(--suong); padding-top: 14px; }
.khoa-hoc dt { font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--thep); padding-top: 3px; }
.khoa-hoc dd { color: var(--muc); }
.khoa-hoc .di { font-family: var(--mono); font-size: 12.5px; color: var(--teal); letter-spacing: 0.06em; text-transform: uppercase; }

/* Đầu trang con: dải tối kỹ thuật */
.trang-dau { position: relative; background: var(--den-xanh); color: var(--trang); overflow: hidden; padding-block: clamp(56px, 7vw, 96px) clamp(48px, 6vw, 80px); isolation: isolate; }
.trang-dau .quang { position: absolute; inset: 0; z-index: 0; pointer-events: none; background: radial-gradient(ellipse 40% 70% at 88% 20%, rgba(31,138,112,0.32), transparent 70%), radial-gradient(ellipse 30% 50% at 5% 100%, rgba(42,127,213,0.16), transparent 70%); }
.trang-dau .luoi { position: absolute; inset: 0; z-index: 0; pointer-events: none; background-image: linear-gradient(rgba(255,255,255,0.07) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,0.07) 1px, transparent 1px); background-size: 72px 72px; mask-image: radial-gradient(ellipse 70% 80% at 60% 50%, #000 10%, transparent 100%); }
.trang-dau .container { position: relative; z-index: 1; display: grid; gap: 18px; max-width: 900px; margin-left: max(var(--gutter), calc((100% - var(--container)) / 2)); }
.trang-dau .nhan { color: var(--xanh-sang); } .trang-dau .nhan::before { background: var(--xanh-sang); }
.trang-dau h1 { color: var(--trang); font-size: clamp(36px, 5vw, 64px); }
.trang-dau h1 em { font-style: normal; color: var(--xanh-sang); }
.trang-dau .dan { color: rgba(255,255,255,0.74); }
.trang-dau time { font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.06em; text-transform: uppercase; color: rgba(255,255,255,0.5); }

/* Dấu 3D trang trí ở đầu trang con và CTA */
.trang-dau-dau { position: absolute; right: -4%; top: 50%; transform: translateY(-50%) rotate(-8deg); width: min(38vw, 520px); opacity: 0.32; z-index: 0; pointer-events: none; filter: drop-shadow(0 30px 60px rgba(0,0,0,0.5)); }
.trang-dau-dau svg { width: 100%; height: auto; }
.cta-cuoi { position: relative; overflow: hidden; }
.cta-dau { position: absolute; right: 6%; top: 50%; transform: translateY(-50%) rotate(-8deg); width: min(26vw, 300px); opacity: 0.18; pointer-events: none; }
.cta-dau svg { width: 100%; height: auto; }
.cta-cuoi .container { position: relative; }
.footer .logo-lon svg { width: min(240px, 60vw); height: auto; }

/* Đầu trang con có hình minh hoạ 3D */
.trang-dau.co-hinh .container { max-width: 620px; }
.trang-dau-hinh { position: absolute; right: max(var(--gutter), calc((100% - var(--container)) / 2)); top: 50%; transform: translateY(-50%) perspective(1200px) rotateY(-6deg); width: min(46%, 640px); margin: 0; border-radius: 16px; overflow: hidden; border: 1px solid rgba(127,209,190,0.25); box-shadow: 0 40px 90px -40px rgba(0,0,0,0.85), 0 0 0 1px rgba(95,227,196,0.05); z-index: 1; }
.trang-dau-hinh img { display: block; width: 100%; height: auto; }
@media (max-width: 960px) { .trang-dau-hinh { position: static; transform: none; width: 100%; margin-top: 24px; } .trang-dau.co-hinh .container { max-width: none; } }

/* Trang nội dung */
.trang { padding-block: clamp(48px, 7vw, 96px); }
.trang .container { display: grid; grid-template-columns: minmax(0, 8fr) minmax(0, 4fr); gap: clamp(32px, 5vw, 72px); align-items: start; }
.noi-dung { display: grid; gap: 20px; max-width: 72ch; }
.noi-dung h1 { font-size: clamp(36px, 4.6vw, 60px); }
.noi-dung > :first-child { margin-top: 0; }
.noi-dung h2 { margin-top: 28px; font-size: clamp(24px, 2.6vw, 32px); }
.noi-dung h3 { margin-top: 12px; }
.noi-dung ul, .noi-dung ol { padding-left: 22px; display: grid; gap: 8px; }
.noi-dung ol { list-style: none; padding-left: 0; counter-reset: q; }
.noi-dung ol li { position: relative; padding-left: 44px; counter-increment: q; }
.noi-dung ol li::before { content: '0' counter(q); position: absolute; left: 0; top: 4px; font-family: var(--mono); font-size: 12px; letter-spacing: 0.06em; color: var(--teal); }
.noi-dung table { width: 100%; border-collapse: collapse; font-size: 15.5px; }
.noi-dung th, .noi-dung td { text-align: left; padding: 12px 10px; border-bottom: 1px solid var(--suong); vertical-align: top; }
.noi-dung th { font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--thep); font-weight: 500; }
.noi-dung blockquote { border-left: 3px solid var(--teal); padding: 6px 0 6px 18px; color: var(--thep); }
.noi-dung hr { border: 0; border-top: 1px solid var(--suong); }
.noi-dung details { border: 1px solid var(--suong); border-radius: 8px; background: var(--trang); }
.noi-dung details summary { cursor: pointer; padding: 14px 18px; font-weight: 600; color: var(--navy); list-style: none; display: flex; justify-content: space-between; gap: 12px; }
.noi-dung details summary::after { content: '+'; color: var(--teal); font-family: var(--mono); font-weight: 600; }
.noi-dung details[open] summary::after { content: '–'; }
.noi-dung details p { padding: 0 18px 16px; color: var(--muc); }
.can-kiem-tra { background: #FFF6DB; border: 1px dashed var(--vang); padding: 2px 6px; border-radius: 3px; font-size: 0.92em; }
.bang-cuon { overflow-x: auto; }

/* Sidebar */
.the { background: var(--trang); border: 1px solid var(--suong); border-radius: 12px; padding: 28px; display: grid; gap: 12px; align-content: start; }
.the p { color: var(--thep); font-size: 16px; }
.ben { position: sticky; top: 92px; display: grid; gap: 16px; }
.ben .the.cta { background: var(--navy-dam); color: var(--trang); border: 0; }
.ben .the.cta h3 { color: var(--trang); } .ben .the.cta p { color: rgba(255,255,255,0.75); }
.ben .the.cta .nut { background: var(--vang); border-color: var(--vang); color: var(--navy-sau); justify-content: center; }
.ben .the.cta .nut:hover { background: var(--trang); border-color: var(--trang); }
.ben .the.cta .nut.phu { background: transparent; border-color: rgba(255,255,255,0.3); color: var(--trang); }
.ben ul { list-style: none; display: grid; gap: 10px; }
.ben li a { color: var(--muc); font-weight: 500; font-size: 15px; }
.ben li a[aria-current="page"] { color: var(--teal); }

/* Danh sách */
.muc-luc { border-top: 1px solid var(--suong); }
.muc-luc a { display: grid; grid-template-columns: 56px minmax(0, 1fr) auto; gap: 20px; align-items: center; padding: 22px 0; border-bottom: 1px solid var(--suong); color: var(--muc); }
.muc-luc a:hover { text-decoration: none; background: var(--trang); }
.muc-luc .so { font-family: var(--mono); color: var(--teal); font-size: 12.5px; letter-spacing: 0.08em; }
.muc-luc b { font-size: 20px; color: var(--navy); font-weight: 700; display: block; }
.muc-luc small { color: var(--thep); font-size: 15px; }
.muc-luc svg { width: 22px; height: 22px; stroke: var(--navy); }
.ds-bai { border-top: 1px solid var(--suong); }
.ds-bai a { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 16px; padding: 20px 0; border-bottom: 1px solid var(--suong); color: var(--muc); }
.ds-bai a:hover { text-decoration: none; }
.ds-bai b { color: var(--navy); font-size: 19px; display: block; }
.ds-bai small { color: var(--thep); }
.ds-bai time { font-family: var(--mono); font-size: 12.5px; color: var(--thep); white-space: nowrap; }
.trong { padding: 32px; border: 1px dashed var(--suong); border-radius: 8px; color: var(--thep); text-align: center; }

/* Form */
.form { display: grid; gap: 16px; background: var(--trang); border: 1px solid var(--suong); border-radius: 12px; padding: 28px; }
.form label { display: grid; gap: 6px; font-weight: 600; font-size: 14px; color: var(--navy); }
.form input, .form select, .form textarea { font: inherit; padding: 12px 14px; border: 1px solid var(--suong); border-radius: 6px; background: var(--kem); min-height: 46px; }
.form textarea { min-height: 110px; resize: vertical; }
.form small { color: var(--thep); font-size: 13px; }

/* CTA cuối & footer */
.cta-cuoi { background: radial-gradient(ellipse 40% 80% at 90% 50%, rgba(31,138,112,0.25), transparent 70%), var(--den-xanh); color: var(--trang); border-top: 1px solid var(--line-toi); }
.cta-cuoi .container { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 32px; align-items: center; }
.cta-cuoi h2 { color: var(--trang); }
.cta-cuoi p { color: rgba(255,255,255,0.72); margin-top: 8px; }
.cta-cuoi .nut { background: var(--vang); border-color: var(--vang); color: var(--navy-sau); }
.cta-cuoi .nut:hover { background: var(--trang); border-color: var(--trang); }
.footer { background: var(--den-xanh); color: rgba(255,255,255,0.78); padding-block: 56px 32px; font-size: 14.5px; border-top: 1px solid var(--line-toi); }
.footer .container { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 40px; }
.footer h4 { color: var(--trang); font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.1em; text-transform: uppercase; font-weight: 500; margin-bottom: 14px; }
.footer ul { list-style: none; display: grid; gap: 8px; }
.footer a { color: rgba(255,255,255,0.78); }
.footer a:hover { color: var(--vang); }
.footer .phap-ly { grid-column: 1 / -1; border-top: 1px solid var(--line-toi); padding-top: 20px; font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.02em; line-height: 1.8; color: rgba(255,255,255,0.5); display: grid; gap: 2px; }
.footer .wordmark-lon { font-size: clamp(64px, 12vw, 160px); font-weight: 800; letter-spacing: 0.06em; line-height: 0.9; color: rgba(255,255,255,0.06); margin-top: 32px; grid-column: 1 / -1; user-select: none; }

/* Nút Zalo nổi */
.zalo-noi { position: fixed; right: 20px; bottom: 20px; z-index: 40; display: inline-flex; align-items: center; gap: 10px; padding: 12px 18px; border-radius: 999px; background: var(--navy); color: var(--trang); font-weight: 700; box-shadow: 0 12px 24px -8px rgba(4,27,43,0.6); border: 1px solid rgba(255,255,255,0.12); }
.zalo-noi:hover { background: var(--teal); text-decoration: none; color: var(--trang); }
.zalo-noi svg { width: 20px; height: 20px; }

/* Responsive */
@media (max-width: 1024px) {
  .bento { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .bento .o, .bento .o.lon, .bento .o.rong, .bento .o.vua { grid-column: span 1; }
  .bento .o.lon { grid-template-columns: 1fr; }
  .khoa-hoc { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 960px) {
  .hero-phai { min-height: 0; display: grid; gap: 16px; }
  .hero .khoi-3d { position: relative; right: auto; top: auto; width: min(100%, 420px); margin: 0 auto; }
  .hero .bang { position: static; width: 100%; transform: none; }
  .hero .container, .trang .container, .footer .container, .cta-cuoi .container, .cong-nghe { grid-template-columns: 1fr; }
  .buoc { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .buoc::before { display: none; }
  .ben { position: static; }
  .trang-dau .container { margin-left: auto; }
  .trang-dau-dau { opacity: 0.16; }
  .muc-luc a { grid-template-columns: 40px minmax(0, 1fr); }
  .muc-luc svg { display: none; }
  .tru-cot .container { grid-template-columns: 1fr; }
  .tru-cot a, .tru-cot a + a { border-right: 0; border-bottom: 1px solid var(--suong); padding: 22px 0; }
  .tru-cot a:last-child { border-bottom: 0; }
  .dau-khoi.hai { grid-template-columns: 1fr; align-items: start; }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .bento, .khoa-hoc, .buoc { grid-template-columns: 1fr; }
  .nav { display: none; position: absolute; left: 0; right: 0; top: 68px; background: var(--navy-sau); border-bottom: 1px solid var(--line-toi); flex-direction: column; align-items: stretch; padding: 16px var(--gutter) 24px; gap: 4px; }
  .nav.mo { display: flex; }
  .nav a { padding: 12px 0; font-size: 17px; }
  .nav .nut { justify-content: center; margin-top: 8px; }
  .nav-toggle { display: inline-flex; }
  .zalo-noi span { display: none; }
  .zalo-noi { padding: 14px; }
  .hero .luoi { background-size: 48px 48px; }
  .hero canvas.cau { width: 120vw; height: 120vw; right: -50vw; top: -20vw; opacity: 0.5; }
  .hero-phai { min-height: 0; display: grid; gap: 16px; }
  .hero .khoi-3d { position: relative; right: auto; top: auto; width: 100%; max-width: 360px; margin: 0 auto; }
  .hero .bang { position: static; width: 100%; transform: none; }
}

/* ===== Hành trình: cảnh 3D cuộn theo bước ===== */
.hanh-trinh { background: var(--den-xanh); }
.ht-luoi { display: grid; grid-template-columns: minmax(0, 6fr) minmax(0, 6fr); gap: clamp(32px, 5vw, 80px); align-items: start; }
.ht-3d { position: sticky; top: 90px; aspect-ratio: 1; max-height: calc(100vh - 120px); }
.ht-3d .canh-3d { position: absolute; inset: 0; }
.ht-3d canvas { width: 100% !important; height: 100% !important; display: block; }
.ht-buoc { list-style: none; display: grid; gap: 12vh; padding-block: 8vh 20vh; }
.ht-buoc li { display: grid; gap: 12px; padding: 28px; border-radius: 16px; border: 1px solid transparent; transition: border-color .4s, background .4s, transform .4s; transform: translateX(0); }
.ht-buoc li.dang { border-color: rgba(95,227,196,0.35); background: rgba(255,255,255,0.03); transform: translateX(6px); }
.ht-buoc .mono { color: var(--xanh-sang); }
.ht-buoc h3 { color: var(--trang); font-size: clamp(22px, 2.2vw, 28px); }
.ht-buoc p { color: rgba(255,255,255,0.7); font-size: 16px; }
.ht-buoc a { color: var(--vang); font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.06em; text-transform: uppercase; }

/* ===== Chồng thẻ 3D trong ô Thành lập ===== */
.chong-the { position: relative; height: 150px; margin: 6px 0 4px; perspective: 700px; }
.chong-the i { position: absolute; left: 6%; right: 6%; top: 40px; height: 84px; border-radius: 10px; background: linear-gradient(135deg, rgba(255,255,255,0.16), rgba(255,255,255,0.04)); border: 1px solid rgba(255,255,255,0.28); backdrop-filter: blur(4px); transform: rotateX(50deg) rotateZ(-14deg) translateZ(var(--z, 0px)); transform-origin: 50% 60%; transition: transform .5s cubic-bezier(.2,.7,.2,1); box-shadow: 0 30px 40px -24px rgba(0,0,0,0.6); display: grid; align-items: end; padding: 10px 12px; }
.chong-the i b { font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.06em; text-transform: uppercase; color: rgba(255,255,255,0.75); font-weight: 500; }
.chong-the i:nth-child(1) { --z: 0px; } .chong-the i:nth-child(2) { --z: 26px; } .chong-the i:nth-child(3) { --z: 52px; border-color: rgba(95,227,196,0.6); }
.bento .o:hover .chong-the i:nth-child(2) { --z: 40px; } .bento .o:hover .chong-the i:nth-child(3) { --z: 80px; }

/* ===== Đèn rọi theo chuột trên nền tối ===== */
.khoi.toi { --mx: 50%; --my: 50%; }
.khoi.toi::after { content: ''; position: absolute; inset: 0; pointer-events: none; background: radial-gradient(600px circle at var(--mx) var(--my), rgba(95,227,196,0.07), transparent 60%); opacity: 0; transition: opacity .4s; }
.khoi.toi:hover::after { opacity: 1; }
.khoi.toi > .container { position: relative; z-index: 1; }

/* ===== Chỉ mục phần cố định ===== */
.chi-muc { position: fixed; right: 22px; top: 50%; transform: translateY(-50%); z-index: 45; display: grid; gap: 14px; mix-blend-mode: difference; }
.chi-muc a { display: flex; align-items: center; gap: 10px; justify-content: flex-end; color: rgba(255,255,255,0.85); font-family: var(--mono); font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; }
.chi-muc a span { opacity: 0; transform: translateX(6px); transition: opacity .2s, transform .2s; color: #fff; padding: 4px 8px; }
.chi-muc a i { width: 8px; height: 8px; border-radius: 50%; border: 1.5px solid rgba(255,255,255,0.8); transition: background .2s, border-color .2s, transform .2s; }
.chi-muc a:hover span, .chi-muc a.dang span { opacity: 1; transform: none; }
.chi-muc a.dang i { background: #fff; border-color: #fff; transform: scale(1.25); }
.chi-muc a:hover { text-decoration: none; color: var(--trang); }
@media (max-width: 1100px) { .chi-muc { display: none; } }
@media (max-width: 960px) { .ht-luoi { grid-template-columns: 1fr; } .ht-3d { position: relative; top: 0; max-height: 420px; } .ht-buoc { gap: 24px; padding-block: 0; } }