:root {
  --ink: #0f172a;
  --muted: #475569;
  --paper: #fff;
  --line: #e2e8f0;
  --brand: #2563eb;
  --brand-ink: #1e40af;
  --soft: #f1f5ff;
  --r: 16px;
  --sh: 0 10px 24px rgba(15, 23, 42, .08);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: Inter, system-ui, Arial, sans-serif;
  line-height: 1.7;
  -webkit-text-size-adjust: 100%;
}

img { max-width: 100%; height: auto; display: block; border-radius: var(--r); }
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

/* -------- Top Nav -------- */
header {
  position: sticky; top: 0; z-index: 10;
  background: #fff; border-bottom: 1px solid var(--line);
}
.wrap { width: min(1160px, 94%); margin: 0 auto; }
.nav { display: flex; justify-content: space-between; align-items: center; padding: .9rem 0; }
.nav a { margin-left: .75rem; padding: .5rem .9rem; border-radius: 999px; }
.nav a:hover { background: var(--soft); text-decoration: none; }

/* -------- Hero -------- */
.hero { background: linear-gradient(180deg, var(--soft), #fff 70%); border-bottom: 1px solid var(--line); }
.hero .wrap {
  display: grid; grid-template-columns: 1.1fr 1fr;
  gap: 1.5rem; align-items: center; padding: 1.6rem 0;
}
h1 { font-size: clamp(1.6rem, 2.8vw, 2.4rem); margin: 0 0 .4rem; }
h2 { font-size: clamp(1.1rem, 1.8vw, 1.6rem); margin: 0 0 .4rem; }
.section { padding: 1.6rem 0; }

/* -------- Cards & Features -------- */
.grid3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.2rem; }
.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--r);
  padding: 1.2rem; box-shadow: var(--sh);
}

.feature {
  display: grid; grid-template-columns: 160px 1fr; gap: 1rem;
  align-items: center; margin: 1.2rem 0;
}
.feature img { height: 160px; width: 100%; object-fit: cover; }

/* -------- Timeline -------- */
.timeline { list-style: none; margin: .6rem 0 0; padding: 0; position: relative; }
.timeline li { position: relative; padding-left: 1.4rem; margin: .5rem 0; }
.timeline li::before {
  content: ""; position: absolute; left: .25rem; top: .6rem;
  width: .55rem; height: .55rem; border-radius: 999px; background: var(--brand);
}

/* -------- Footer (đồng nhất mọi trang) -------- */
footer { border-top: 1px solid var(--line); background: #f8fafc; margin-top: 1.2rem; }
.footer-wrap { width: min(1160px,94%); margin: 0 auto; padding: 1.2rem 0; }
.footer-grid { display: grid; gap: 1rem; grid-template-columns: 1fr; }
.footer-col .small { color: var(--muted); }
.footer-col a { color: var(--ink); }
.footer-col a:hover { color: var(--brand-ink); }

/* -------- Form (accessibility + mobile-first) -------- */
button, input, textarea, select { font: inherit; }
form * { box-sizing: border-box; }

.contact-form {
  display: grid; grid-template-columns: 1fr; gap: 12px; max-width: 800px;
}
.contact-form .row-2 {
  display: grid; grid-template-columns: 1fr 1fr; gap: 12px;
}
.contact-form input,
.contact-form textarea {
  width: 100%; padding: .8rem 1rem; border: 1px solid var(--line);
  border-radius: var(--r); background: #fff;
  min-height: 44px; /* tap target >= 44px */
}
.contact-form textarea { resize: vertical; }
.contact-form button {
  width: auto; justify-self: start; padding: .85rem 1.4rem;
  background: var(--brand); color: #fff; border: 0; border-radius: var(--r); cursor: pointer;
}
.contact-form button:hover { background: var(--brand-ink); }

/* -------- Responsive tweaks -------- */
@media (min-width: 860px) {
  .hero .wrap { grid-template-columns: 1.1fr 1fr; text-align: left; }
  .feature { grid-template-columns: 160px 1fr; text-align: left; }
  .footer-grid { grid-template-columns: 1.2fr 1fr 1fr; align-items: start; }
}
@media (max-width: 859.98px) {
  .hero .wrap { grid-template-columns: 1fr; text-align: center; }
  .feature { grid-template-columns: 1fr; text-align: center; }
  .nav { flex-wrap: wrap; gap: .4rem .6rem; }
}
@media (max-width: 640px) {
  .contact-form .row-2 { grid-template-columns: 1fr; }
}