/* Reset */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }

html { scroll-behavior: smooth; scroll-padding-top: var(--header-h); }

body {
  font-family: var(--font-main);
  font-size: var(--fs-body);
  line-height: 1.6;
  color: var(--text);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

img, video { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

/* Layout */
.container { width: 100%; max-width: var(--container); margin-inline: auto; padding-inline: 24px; }
.narrow { max-width: 820px; }

section { padding-block: var(--space-section); }

/* Nền tối + nhịp tương phản */
.section-dark { background: var(--dark-blue); color: var(--white); }
.section-dark .section-lead,
.section-dark .section-sub { color: #c5c5c5; }

/* Tiêu đề chung */
.section-head { text-align: center; margin-bottom: 3.5rem; }
.section-title {
  font-size: var(--fs-h2);
  font-weight: 600;
  line-height: 1.0;
  letter-spacing: -0.6px;
}
.section-lead {
  font-size: clamp(1.1rem, 2vw, 1.5rem);
  font-weight: 600;
  color: var(--text-muted);
  margin-top: 0.75rem;
}
.section-sub {
  font-size: var(--fs-body);
  color: var(--text-muted);
  max-width: 760px;
  margin: 1.25rem auto 0;
}

/* Nút */
.btn {
  display: inline-block;
  font-weight: 700;
  font-size: 1rem;
  padding: 0.95rem 2.2rem;
  border-radius: 999px;
  cursor: pointer;
  border: none;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}
.btn-primary { background: var(--brand); color: var(--white); }
.btn-primary:hover {
  background: var(--brand-dark);
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(0, 137, 247, 0.35);
}

/* Hiệu ứng hiện dần khi cuộn (JS thêm .in-view) */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.in-view { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
}