/* ============================================================
   QS Tech — Base styles (reset + typography + utilities)
   ============================================================ */

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-ink);
  font-family: var(--f-sans);
  font-size: var(--t-base);
  line-height: var(--lh-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img, svg, video { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; transition: color var(--d-normal) var(--ease); }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }
ul, ol { margin: 0; padding: 0; list-style: none; }
p { margin: 0 0 1rem; }
p:last-child { margin-bottom: 0; }
input, select, textarea { font: inherit; }

:focus-visible {
  outline: 2px solid var(--c-accent-deep);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  padding: 0.75rem 1.25rem;
  background: var(--c-ink);
  color: var(--c-bg);
  z-index: var(--z-toast);
  font-weight: 500;
}
.skip-link:focus { left: 1rem; top: 1rem; }

.container {
  padding-inline: var(--pad-x);
  max-width: var(--container-max);
  margin-inline: auto;
}

.display {
  font-family: var(--f-display);
  font-weight: 600;
  line-height: var(--lh-tight);
  letter-spacing: var(--ls-tight);
}
.eyebrow {
  font-size: var(--t-xs);
  text-transform: uppercase;
  letter-spacing: var(--ls-wide);
  color: var(--c-brand);
  font-weight: 700;
}

.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;
}

/* ============ REVEAL ANIMATION ============ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.8s var(--ease), transform 0.8s var(--ease);
  will-change: opacity, transform;
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}
.reveal[data-delay="1"] { transition-delay: 80ms; }
.reveal[data-delay="2"] { transition-delay: 160ms; }
.reveal[data-delay="3"] { transition-delay: 240ms; }
.reveal[data-delay="4"] { transition-delay: 320ms; }

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

/* ============ SECTION ============ */
.section { padding: var(--pad-section) 0; }
.section-head {
  text-align: center;
  margin-bottom: 3rem;
}
.section-head .eyebrow {
  display: inline-block;
  margin-bottom: 0.7rem;
}
/* Highlighter vàng logo ở nửa dưới chữ eyebrow — nhấn nhận diện QS Tech */
.section-head .eyebrow,
.page-hero .eyebrow {
  background: linear-gradient(transparent 58%, var(--c-yellow) 58%);
  padding: 0 0.3em 0.06em;
}
.section-head h2 {
  font-family: var(--f-display);
  font-size: var(--t-section);
  line-height: 1.16;
  margin: 0 0 0.8rem;
  font-weight: 600;
  letter-spacing: var(--ls-tight);
}
.section-head h2 .accent { color: var(--c-accent); font-style: italic; }
.section-head p {
  color: var(--c-ink-soft);
  max-width: 56ch;
  margin: 0 auto;
}

/* ============ BUTTONS ============ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.2rem;
  font-size: 0.88rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: transform var(--d-normal) var(--ease), background var(--d-normal) var(--ease), box-shadow var(--d-normal) var(--ease), border-color var(--d-normal) var(--ease);
  cursor: pointer;
  white-space: nowrap;
}
.btn-primary {
  background: var(--c-accent-deep);
  color: oklch(99% 0 0);
  box-shadow: 0 6px 18px -8px oklch(45% 0.18 50 / 0.55);
}
.btn-primary:hover {
  background: oklch(39% 0.19 45);
  color: oklch(99% 0 0);
  transform: translateY(-1px);
  box-shadow: 0 10px 24px -8px oklch(45% 0.18 50 / 0.6);
}
.btn-ghost {
  border: 1px solid var(--c-line);
  color: var(--c-ink);
}
.btn-ghost:hover { border-color: var(--c-ink); }
.btn-dark {
  background: var(--c-brand-deep);
  color: var(--c-bg);
}
.btn-dark:hover {
  background: oklch(12% 0.06 250);
  transform: translateY(-1px);
}
.btn-lg { padding: 0.95rem 1.6rem; font-size: 0.95rem; }
.btn-block { width: 100%; justify-content: center; }
.btn .arr { transition: transform var(--d-normal) var(--ease); }
.btn:hover .arr { transform: translateX(4px); }