/**
 * BASE CSS & TYPOGRAPHY — DA ĐẸP MỖI NGÀY
 * Tuân thủ mục 3 & 4 trong DESIGN.md
 */

/* === CSS Reset & Box Sizing === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  font-size: 1rem; /* 16px */
  line-height: 1.7;
  color: var(--color-text-secondary);
  background-color: var(--color-background); /* Nền ngà Ivory #FAF7F4 */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, picture, svg, video {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--duration-fast) ease;
}

a:hover {
  color: var(--color-primary-hover);
}

ul, ol {
  list-style: none;
}

button, input, textarea, select {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

/* === Typography Classes & Base Elements === */
h1, h2, h3, h4, .display, .h1, .h2, .h3, .h4 {
  font-family: var(--font-heading);
  color: var(--color-text-primary);
  font-weight: 600;
  margin-bottom: 0.5em;
  line-height: 1.2;
}

.display {
  font-size: 4rem; /* 64px */
  line-height: 1.12;
  letter-spacing: -0.02em;
}

h1, .h1 {
  font-size: 3rem; /* 48px */
  line-height: 1.15;
  letter-spacing: -0.015em;
}

h2, .h2 {
  font-size: 2.25rem; /* 36px */
  line-height: 1.2;
  letter-spacing: -0.01em;
}

h3, .h3 {
  font-size: 1.75rem; /* 28px */
  line-height: 1.25;
}

h4, .h4 {
  font-size: 1.375rem; /* 22px */
  line-height: 1.3;
}

.body-large {
  font-family: var(--font-body);
  font-size: 1.125rem; /* 18px */
  line-height: 1.65;
  font-weight: 400;
  color: var(--color-text-secondary);
}

.body-text, p {
  font-family: var(--font-body);
  font-size: 1rem; /* 16px */
  line-height: 1.7;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
}

/* Guardrail: Giới hạn chiều rộng đoạn văn để tối ưu trải nghiệm đọc (65-75 ký tự) */
.readable-measure {
  max-width: 42rem;
}

.small-text, small {
  font-family: var(--font-body);
  font-size: 0.875rem; /* 14px */
  line-height: 1.6;
  color: var(--color-text-secondary);
}

.caption {
  font-family: var(--font-body);
  font-size: 0.75rem; /* 12px */
  line-height: 1.5;
  letter-spacing: 0.04em;
  font-weight: 500;
  color: var(--color-text-tertiary);
}

.caption-label {
  font-family: var(--font-body);
  font-size: 0.75rem; /* 12px */
  line-height: 1.5;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}

.price-current {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-primary);
}

.price-original {
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--color-text-tertiary);
  text-decoration: line-through;
  margin-left: var(--space-2);
}

/* === Layout & Containers === */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
}

.container-narrow {
  width: 100%;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
}

.section {
  padding-top: var(--section-padding);
  padding-bottom: var(--section-padding);
  position: relative;
}

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

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

.section-deep {
  background-color: var(--color-primary-deep);
  color: var(--color-text-on-deep);
}

.section-deep h1,
.section-deep h2,
.section-deep h3,
.section-deep h4 {
  color: var(--color-text-on-deep);
}

.section-deep p,
.section-deep .body-text {
  color: rgba(243, 236, 230, 0.85);
}

.section-header {
  margin-bottom: var(--space-9); /* 48px */
}

.section-header.text-center {
  text-align: center;
}

.section-header.text-center .eyebrow {
  justify-content: center;
}

.section-header.text-center p {
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

/* Guardrail: Cấm text-align center cho đoạn văn dài hơn 3 dòng */
.section-header p {
  max-width: 38rem;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
  transition: color var(--duration-fast) var(--ease), transform var(--duration-fast) var(--ease);
}

a.eyebrow:hover {
  color: var(--color-primary-hover);
  transform: translateX(2px);
}

.eyebrow-secondary {
  color: var(--color-secondary);
}

/* === Grid System === */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--grid-gap);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--grid-gap);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--grid-gap);
}

.split-50 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-10);
  align-items: center;
}

.split-40-60 {
  display: grid;
  grid-template-columns: 0.4fr 0.6fr;
  gap: var(--space-10);
  align-items: center;
}

.split-60-40 {
  display: grid;
  grid-template-columns: 0.6fr 0.4fr;
  gap: var(--space-10);
  align-items: center;
}

/* === Focus Visible Accessibility === */
a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* === Motion Accessibility === */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* === Mobile Typography Scale (< 768px) === */
@media (max-width: 767px) {
  .display {
    font-size: 2.5rem; /* 40px */
    line-height: 1.15;
  }

  h1, .h1 {
    font-size: 2rem; /* 32px */
    line-height: 1.2;
  }

  h2, .h2 {
    font-size: 1.625rem; /* 26px */
    line-height: 1.25;
  }

  h3, .h3 {
    font-size: 1.375rem; /* 22px */
    line-height: 1.3;
  }

  h4, .h4 {
    font-size: 1.1875rem; /* 19px */
    line-height: 1.35;
  }

  .body-large {
    font-size: 1.0625rem; /* 17px */
    line-height: 1.65;
  }

  .body-text, p {
    font-size: 0.9375rem; /* 15px */
    line-height: 1.7;
  }

  .small-text, small {
    font-size: 0.8125rem; /* 13px */
  }

  .caption {
    font-size: 0.6875rem; /* 11px */
  }

  .section {
    padding-top: var(--section-padding-mobile);
    padding-bottom: var(--section-padding-mobile);
  }

  .container {
    padding-left: var(--container-padding-mobile);
    padding-right: var(--container-padding-mobile);
  }

  .grid-2,
  .grid-3,
  .grid-4,
  .split-50,
  .split-40-60,
  .split-60-40 {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }
}

/* === Tablet Breakpoint (768px - 1023px) === */
@media (min-width: 768px) and (max-width: 1023px) {
  .grid-3, .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .split-50, .split-40-60, .split-60-40 {
    gap: var(--space-7);
  }
}