/* DNU AI Office — landing
   Màu thương hiệu lấy từ logo Trường: cam #F07423, navy #21409A.
   Cam chỉ dùng cho điểm nhấn trang trí (đường kẻ, chấm, viền) vì tương phản
   cam-trên-trắng chỉ ~3:1, không đạt 4,5:1 cho chữ. Chữ dùng navy hoặc mực đậm. */

:root {
  --cam: #f07423;
  --cam-nhat: #fdece1;
  --cam-dam: #8a3a0b;
  --navy: #21409a;
  --navy-dam: #172c6b;
  --muc: #14181f;
  --muc-nhat: #4a5361;
  --vien: #dfe3ea;
  --nen: #ffffff;
  --nen-phu: #f6f7fa;
  --ban-kinh: 10px;
  --khoang: 8px;
  --font: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  color: var(--muc);
  background: var(--nen);
}

img { max-width: 100%; height: auto; }

a { color: var(--navy); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible,
button:focus-visible { outline: 3px solid var(--navy); outline-offset: 2px; }

.wrap { width: 100%; max-width: 1120px; margin: 0 auto; padding: 0 24px; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* ---------- đầu trang ---------- */

.site-header {
  position: sticky; top: 0; z-index: 10;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--vien);
  border-top: 4px solid var(--cam);
}

.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; min-height: 68px;
}

.brand { display: flex; align-items: center; gap: 14px; color: var(--muc); }
.brand:hover { text-decoration: none; }
.brand-divider { width: 1px; height: 26px; background: var(--vien); }
.brand-product { font-weight: 700; font-size: 17px; letter-spacing: -0.01em; }

.site-nav { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.site-nav a {
  padding: 8px 12px; border-radius: 8px; font-size: 15px; font-weight: 500;
  color: var(--muc-nhat);
}
.site-nav a:hover { background: var(--nen-phu); color: var(--muc); text-decoration: none; }
.site-nav .nav-cta { background: var(--navy); color: #fff; font-weight: 600; }
.site-nav .nav-cta:hover { background: var(--navy-dam); color: #fff; }

/* ---------- khối mở đầu ---------- */

.hero { padding: 56px 0 64px; border-bottom: 1px solid var(--vien); }
.hero-inner {
  display: grid; grid-template-columns: 1.05fr 0.95fr;
  gap: 48px; align-items: center;
}

.eyebrow {
  margin: 0 0 12px; font-size: 13px; font-weight: 700; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--navy);
}

h1 {
  margin: 0 0 16px; font-size: 40px; line-height: 1.18;
  letter-spacing: -0.02em; color: var(--muc);
}

.lede { margin: 0 0 28px; font-size: 17px; color: var(--muc-nhat); max-width: 56ch; }

.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 16px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 46px; padding: 0 22px; border-radius: var(--ban-kinh);
  font-size: 16px; font-weight: 600; border: 1px solid transparent;
  cursor: pointer;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--navy); color: #fff; }
.btn-primary:hover { background: var(--navy-dam); }
.btn-ghost { background: #fff; color: var(--navy); border-color: var(--vien); }
.btn-ghost:hover { background: var(--nen-phu); color: var(--navy-dam); }
.btn-onbrand { background: #fff; color: var(--navy-dam); }
.btn-onbrand:hover { background: #eef1f8; }

.hero-note { margin: 0; font-size: 14px; color: var(--muc-nhat); }

/* hình minh hoạ: khối thuần CSS, không tải ảnh ngoài */
.hero-figure {
  border: 1px solid var(--vien); border-radius: 14px; overflow: hidden;
  background: var(--nen); box-shadow: 0 18px 40px -24px rgba(20, 24, 31, 0.35);
}
.fig-bar {
  display: flex; gap: 6px; padding: 10px 12px;
  background: var(--nen-phu); border-bottom: 1px solid var(--vien);
}
.fig-bar span { width: 9px; height: 9px; border-radius: 50%; background: var(--vien); }
.fig-bar span:first-child { background: var(--cam); }

.fig-body { display: grid; grid-template-columns: 92px 1fr; min-height: 300px; }
.fig-side {
  padding: 16px 12px; border-right: 1px solid var(--vien);
  display: flex; flex-direction: column; gap: 12px; background: #fbfcfe;
}
.fig-line { height: 7px; border-radius: 4px; background: var(--vien); }
.w70 { width: 70%; } .w62 { width: 62%; } .w55 { width: 55%; } .w48 { width: 48%; }

.fig-main { padding: 18px 18px 0; }
.fig-title {
  margin: 0 0 14px; font-size: 13px; font-weight: 700;
  color: var(--muc-nhat); letter-spacing: 0.02em;
}
.fig-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.fig-card {
  border: 1px solid var(--vien); border-radius: 8px; padding: 12px 10px;
  display: flex; flex-direction: column; gap: 3px; background: #fff;
}
.fig-card b { font-size: 12px; color: var(--muc); }
.fig-card i { font-style: normal; font-size: 11px; color: var(--muc-nhat); }
.fig-card:nth-child(1) { border-top: 3px solid var(--navy); }
.fig-card:nth-child(2) { border-top: 3px solid #1f7a4d; }
.fig-card:nth-child(3) { border-top: 3px solid var(--cam); }
.fig-card:nth-child(4) { border-top: 3px solid #6a3fa0; }
.fig-card:nth-child(5) { border-top: 3px solid #a8791b; }
.fig-card:nth-child(6) { border-top: 3px solid #b3261e; }

.fig-rows { display: flex; flex-direction: column; gap: 10px; margin: 18px -18px 0; }
.fig-row { height: 34px; border-top: 1px solid var(--vien); background: #fcfdff; }

/* ---------- các khối nội dung ---------- */

.section { padding: 64px 0; }
.section-alt { background: var(--nen-phu); border-top: 1px solid var(--vien); border-bottom: 1px solid var(--vien); }

.section-title {
  margin: 0 0 12px; font-size: 28px; line-height: 1.28;
  letter-spacing: -0.01em; color: var(--muc);
  padding-left: 14px; border-left: 4px solid var(--cam);
}
.section-lede { margin: 0 0 32px; color: var(--muc-nhat); max-width: 64ch; }

.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 28px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; margin-top: 28px; }

.card {
  background: #fff; border: 1px solid var(--vien); border-radius: var(--ban-kinh);
  padding: 22px 22px 24px;
}
.card h3 { margin: 0 0 8px; font-size: 17px; line-height: 1.35; color: var(--muc); }
.card p { margin: 0; font-size: 15px; color: var(--muc-nhat); }

.section-alt .card { background: #fff; }

.tag {
  display: inline-block; margin-left: 6px; padding: 1px 8px;
  border-radius: 999px; background: var(--cam-nhat); color: var(--cam-dam);
  font-size: 12px; font-weight: 700; vertical-align: 2px;
}

/* ba bước */
.steps { list-style: none; margin: 32px 0 0; padding: 0; display: grid; gap: 16px; }
.steps li {
  display: grid; grid-template-columns: 44px 1fr; gap: 16px;
  background: #fff; border: 1px solid var(--vien); border-radius: var(--ban-kinh);
  padding: 20px 22px; align-items: start;
}
.step-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 36px; height: 36px; border-radius: 50%;
  background: var(--navy); color: #fff; font-weight: 700; font-size: 16px;
}
.steps h3 { margin: 2px 0 6px; font-size: 17px; }
.steps p { margin: 0; font-size: 15px; color: var(--muc-nhat); }

/* bảng yêu cầu */
.spec {
  width: 100%; border-collapse: collapse; margin-top: 28px;
  background: #fff; border: 1px solid var(--vien); border-radius: var(--ban-kinh);
  overflow: hidden;
}
.spec th, .spec td {
  text-align: left; padding: 14px 18px; border-bottom: 1px solid var(--vien);
  font-size: 15px; vertical-align: top;
}
.spec tr:last-child th, .spec tr:last-child td { border-bottom: 0; }
.spec th { width: 220px; font-weight: 600; color: var(--muc); background: #fbfcfe; }
.spec td { color: var(--muc-nhat); }

/* dải kêu gọi */
.cta-band {
  background: var(--navy); color: #fff; padding: 44px 0;
  border-top: 4px solid var(--cam);
}
.cta-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.cta-band h2 { margin: 0 0 6px; font-size: 24px; color: #fff; }
.cta-band p { margin: 0; color: #dfe6fb; font-size: 15px; }

/* chân trang */
.site-footer { background: #fff; border-top: 1px solid var(--vien); padding: 32px 0 40px; }
.footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-brand { display: flex; align-items: center; gap: 16px; }
.footer-org { border-left: 1px solid var(--vien); padding-left: 16px; }
.org-1 { margin: 0; font-weight: 700; font-size: 15px; color: var(--muc); }
.org-2 { margin: 2px 0 0; font-size: 14px; color: var(--muc-nhat); }
.footer-meta { text-align: right; }
.footer-meta p { margin: 0; font-size: 14px; color: var(--muc-nhat); }
.footer-meta p + p { margin-top: 4px; }

/* ---------- màn hẹp ---------- */
@media (max-width: 940px) {
  .hero-inner { grid-template-columns: 1fr; gap: 32px; }
  .hero-figure { order: -1; }
  h1 { font-size: 32px; }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 680px) {
  .header-inner { flex-wrap: wrap; min-height: 0; padding-top: 10px; padding-bottom: 10px; }
  .brand-divider, .brand-product { display: none; }
  .site-nav { width: 100%; justify-content: flex-start; gap: 4px; }
  .site-nav a { padding: 8px 10px; font-size: 14px; }
  .hero { padding: 32px 0 40px; }
  h1 { font-size: 27px; }
  .lede { font-size: 16px; }
  .section { padding: 44px 0; }
  .section-title { font-size: 23px; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .fig-body { grid-template-columns: 1fr; }
  .fig-side { display: none; }
  .fig-cards { grid-template-columns: repeat(2, 1fr); }
  .spec th { width: auto; }
  .spec, .spec tbody, .spec tr, .spec th, .spec td { display: block; }
  .spec tr { border-bottom: 1px solid var(--vien); }
  .spec th { border-bottom: 0; padding-bottom: 0; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
  .footer-meta { text-align: left; }
  .cta-inner { flex-direction: column; align-items: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}