:root {
  color-scheme: light;
  --ink: #171412;
  --muted: #716c69;
  --line: #dfdad6;
  --paper: #fffcf8;
  --card: #ffffff;
  --orange: #ff5708;
  --orange-soft: #ffeadf;
  --danger: #b3261e;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 16px/1.65 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
a { color: #b63a00; text-underline-offset: 3px; }
.shell { width: min(860px, calc(100% - 32px)); margin: 0 auto; }
header { padding: 30px 0 18px; border-bottom: 1px solid var(--line); }
.brand-row { display: flex; align-items: center; }
.brand { display: flex; align-items: center; gap: 12px; font-weight: 900; letter-spacing: .1em; }
.brand-icon { width: 54px; height: 54px; object-fit: contain; flex: 0 0 auto; }
nav { display: flex; flex-wrap: wrap; gap: 16px; margin-top: 18px; }
nav a { color: var(--muted); font-weight: 700; text-decoration: none; }
main { padding: 42px 0 70px; }
h1 { font-size: clamp(2rem, 6vw, 3.5rem); line-height: 1.02; letter-spacing: -.04em; margin: 0 0 14px; }
h2 { margin-top: 38px; line-height: 1.2; }
h3 { margin-top: 25px; }
.lead { color: var(--muted); font-size: 1.12rem; max-width: 720px; }
.meta, .fine { color: var(--muted); font-size: .92rem; }
.notice, .form-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 22px;
  padding: 22px;
  margin: 26px 0;
}
.notice { border-left: 5px solid var(--orange); }
.danger { border-left-color: var(--danger); }
ul { padding-left: 22px; }
li + li { margin-top: 8px; }
[data-lang="vi"] { display: none; }
label { display: block; font-weight: 800; margin: 16px 0 7px; }
input, select {
  width: 100%; border: 1px solid var(--line); border-radius: 14px;
  background: white; padding: 13px 14px; font: inherit;
}
.check { display: flex; gap: 10px; align-items: flex-start; font-weight: 600; }
.check input { width: 20px; height: 20px; margin-top: 3px; }
button.primary {
  width: 100%; margin-top: 20px; border: 0; border-radius: 15px;
  padding: 14px 18px; background: var(--orange); color: white;
  font: inherit; font-weight: 900; cursor: pointer;
}
button.primary:disabled { opacity: .55; cursor: wait; }
.result { margin-top: 18px; padding: 14px; border-radius: 13px; background: var(--orange-soft); }
footer { border-top: 1px solid var(--line); color: var(--muted); padding: 28px 0 44px; }
@media (max-width: 600px) {
  header { padding-top: 20px; }
  .brand { gap: 9px; letter-spacing: .07em; font-size: .88rem; }
  .brand-icon { width: 46px; height: 46px; }
}