/* ==========================================================================
   NAM NGUYỄN TECH — Base styles (reset, typography, layout primitives)
   ========================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  font-family: var(--font-base);
  background: var(--background);
  color: var(--text);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: inherit;
  text-decoration: none;
}

ul,
ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

button {
  font-family: inherit;
  cursor: pointer;
}

input,
textarea,
select {
  font-family: inherit;
  font-size: 16px;
}

h1,
h2,
h3,
h4,
p {
  margin: 0;
}

h1 {
  font-size: clamp(2.1rem, 4.2vw, 3.4rem);
  line-height: 1.15;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}

h2 {
  font-size: clamp(1.65rem, 2.6vw, 2.25rem);
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text);
}

h3 {
  font-size: 1.2rem;
  line-height: 1.35;
  font-weight: 600;
  color: var(--text);
}

p {
  font-size: 1.0625rem;
  color: var(--text-muted);
}

/* Accessibility: visible focus state everywhere */
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--primary);
  color: #fff;
  padding: 12px 18px;
  z-index: 1000;
  border-radius: 0 0 var(--radius-sm) 0;
}

.skip-link:focus {
  left: 0;
}

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

.section {
  padding-block: var(--section-spacing);
}

.section--sm {
  padding-block: var(--section-spacing-sm);
}

.section--dark {
  background: var(--primary-dark);
  color: var(--text-inverse);
}

.section--surface {
  background: var(--surface);
}

.section--tight-top {
  padding-top: 0;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
}

.section--dark .eyebrow {
  color: #9DC1E0;
}

.section-header {
  max-width: 640px;
  margin-bottom: 48px;
}

.section-header h2 {
  margin-top: 12px;
}

.section-header p {
  margin-top: 14px;
}

.section-header--center {
  margin-inline: auto;
  text-align: center;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

@media (max-width: 768px) {
  :root {
    --section-spacing: 64px;
    --section-spacing-sm: 44px;
  }
}