/* ============================================================
   WiHub — main.css  (1 file shared cho mọi page)
   Gồm: design tokens · global/reset · section helpers ·
        SHARED COMPONENTS (navbar · footer · buttons · contact · news-card)
   Load order: vendor → THIS FILE → pages/[page].css
   (hero + card-capability chỉ ở home → nằm trong pages/index.css)
   ============================================================ */

/* ── Design Tokens ───────────────────────────────────────── */
:root {
  /* Brand */
  --color-brand-dark:       #141240;
  --color-brand-default:    #0d50a1;
  --color-brand-light:      #1aa4dd;
  --color-brand-complement: #1871dc;

  /* Text */
  --color-text-main:        #141240;
  --color-text-secondary:   #4e517a;
  --color-text-tertiary:    #7a879a;
  --color-text-placeholder: #9ea7b5;

  /* White alpha */
  --color-white:            #ffffff;
  --color-white-90:         rgba(255, 255, 255, 0.9);
  --color-white-80:         rgba(255, 255, 255, 0.8);
  --color-white-70:         rgba(255, 255, 255, 0.7);
  --color-white-60:         rgba(255, 255, 255, 0.6);
  --color-white-50:         rgba(255, 255, 255, 0.5);
  --color-white-20:         rgba(255, 255, 255, 0.2);
  --color-white-12:         rgba(255, 255, 255, 0.12);
  --color-white-10:         rgba(255, 255, 255, 0.1);
  --color-white-96:         rgba(255, 255, 255, 0.96);

  /* Section backgrounds */
  --color-bg-blue:          #f6f9fc;
  --color-bg-yellow:        #f9f8f5;
  --color-bg-icon:          #f3f3f3;
  --color-bg-dark:          #141240;

  /* Borders */
  --color-border:           #e5edf5;
  --color-border-divider:   #c8d2e1;

  /* Spacing */
  --space-1: 4px;   --space-2: 8px;   --space-3: 12px;  --space-4: 16px;
  --space-5: 20px;  --space-6: 24px;  --space-8: 32px;  --space-10: 40px;
  --space-12: 48px; --space-16: 64px; --space-20: 80px; --space-24: 96px;

  /* Border radius */
  --radius-sm:  4px;  --radius-md:  8px;  --radius-lg:  12px;
  --radius-xl:  16px; --radius-2xl: 24px; --radius-pill: 100px;

  /* Shadows */
  --shadow-card: 0px 0.5px 2px rgba(36, 63, 97, 0.12), 0px 2px 12px rgba(36, 63, 97, 0.11);
  --shadow-card-hover: 0px 4px 24px rgba(36, 63, 97, 0.18);
  --shadow-nav:  0px 1px 4px rgba(12, 12, 13, 0.04), 0px 4px 16px rgba(12, 12, 13, 0.08);
  --shadow-btn:  0 1px 4px rgba(12, 12, 13, 0.1), 0 1px 4px rgba(12, 12, 13, 0.05);
  --shadow-btn-primary: 0 4px 8px -1px rgba(12, 12, 13, 0.1), 0 1px 1px -1px rgba(12, 12, 13, 0.05);
  --focus-ring:  0 0 0 3px rgba(13, 80, 161, 0.15);

  /* Brand gradients (nút primary) */
  --gradient-primary:       linear-gradient(98.2deg, #0d50a1 1.8%, #1871dc 92.8%);
  --gradient-primary-hover: linear-gradient(98.2deg, #1871dc 1.8%, #2aabe8 92.8%);

  /* Typography */
  --font-family:    'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-size-xs:   12px; --font-size-sm:   14px; --font-size-base: 16px;
  --font-size-lg:   18px; --font-size-xl:   20px; --font-size-2xl:  24px;
  --font-size-3xl:  30px; --font-size-4xl:  36px; --font-size-5xl:  48px;
  --font-size-6xl:  60px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Navbar */
  --navbar-height: 72px;
}

/* ── Base Reset ──────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }
html, body { min-height: 100%; }

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  color: var(--color-text-main);
  background-color: var(--color-white);
  overflow-x: clip;          /* chặn tràn ngang nhưng KHÔNG tạo scroll-container → position:sticky vẫn chạy */
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family);
  color: var(--color-text-main);
  line-height: 1.2;
  margin-bottom: 0;
}

/* ── Section heading pattern: "Label / Title accent" ─────── */
.section-label {
  display: block;
  font-size: var(--font-size-xl);   /* 20px */
  font-weight: 700;
  color: var(--color-brand-dark);
  margin-bottom: var(--space-2);
}
.section-label--light { color: var(--color-white); }

/* Section title — v1.1: 46px/800, line-height 1.3, chữ GRADIENT xanh (đo :8080) */
.section-title {
  font-size: clamp(30px, 4vw, 46px);
  font-weight: 800;
  line-height: 1.3;
  background-image: linear-gradient(91deg, #6598ea 29.5%, #1b5bd2 70.7%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
/* dark-bg sections: gradient sáng hơn cho tương phản (đo v1.1) */
.section-title--light {
  background-image: linear-gradient(91deg, #6597e9 29.5%, #91b0eb 65.7%);
  color: transparent;
}
.section-title em,
.section-title .accent { font-style: normal; }

.section-desc {
  font-size: var(--font-size-base);
  font-weight: 400;
  line-height: 1.7;
  color: var(--color-text-secondary);
}
.section-desc--light { color: var(--color-white-70); }

/* ── Layout ──────────────────────────────────────────────── */
.section-padding {
  padding-top: var(--space-20);
  padding-bottom: var(--space-20);
}
@media (max-width: 768px) {
  .section-padding {
    padding-top: var(--space-12);
    padding-bottom: var(--space-12);
  }
}

/* ── Mobile: giảm gutter lớn để tránh tràn ngang (g-5 = 3rem âm margin > padding container) ── */
@media (max-width: 575.98px) {
  .row.g-5,
  .row.g-4 {
    --bs-gutter-x: 1.5rem;
  }
}


/* ==========================================================================
   SHARED COMPONENTS (gộp vào main.css để ít file, dễ quản lý)
   navbar · footer · buttons · contact · news-card — dùng chung nhiều page.
   ========================================================================== */
/* ==========================================================================
   Component: Navbar  (ground truth: v1.1 render @1920)
   Bar = frosted trắng [rgba(255,255,255,.9) + blur(50px)], logo/links TỐI, CTA xanh đặc
   ========================================================================== */

.site-navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1030;
  min-height: var(--navbar-height);
  padding: 9px 0;
  background: var(--color-white-90);
  -webkit-backdrop-filter: blur(50px);
  backdrop-filter: blur(50px);
  border-bottom: 1px solid var(--color-white-20);
  transition: background var(--transition-base), box-shadow var(--transition-base);

  &.is-scrolled {
    background: var(--color-white-96);
    box-shadow: var(--shadow-nav);
  }
  & .container-xl { min-height: calc(var(--navbar-height) - 18px); }
}

/* --- Brand logo (dark) -------------------------------------------------- */
.site-navbar__logo { height: 32px; width: auto; }
.site-navbar__logo--white { display: none; }
.site-navbar__logo--dark { display: block; }

/* --- Nav links (#4e517a secondary, 15px/500) ---------------------------- */
.site-navbar__link {
  color: var(--color-text-secondary);
  font-size: 15px;
  font-weight: 500;
  line-height: 1;
  padding: 8px 12px;
  border-radius: var(--radius-md);  /* 8px — v1.1 pill radius */
  transition: color var(--transition-fast), background-color var(--transition-fast);

  /* v1.1: hover = PILL NỀN xanh nhẹ (bg fill, KHÔNG viền) + chữ navy đậm */
  &:hover,
  &:focus {
    color: var(--color-brand-dark);                 /* #141240 navy */
    background-color: rgba(24, 113, 220, 0.12);     /* nền xanh nhẹ */
  }
}

/* --- CTA "Liên Hệ Ngay": solid #0d50a1, chữ trắng, radius 12px ---------- */
.site-navbar__cta {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 20px;
  font-size: 16px;
  font-weight: 600;
  line-height: 1;
  color: var(--color-white);
  background-color: var(--color-brand-default);
  border: 1px solid var(--color-brand-default);
  border-radius: 12px;
  box-shadow: var(--shadow-btn);
  transition: background-color var(--transition-base), color var(--transition-base);

  /* hover: xanh NHẠT HƠN #1871dc */
  &:hover,
  &:focus {
    background-color: var(--color-brand-complement);
    border-color: var(--color-brand-complement);
    color: var(--color-white);
  }
}

/* --- Toggler ------------------------------------------------------------- */
.site-navbar__toggler {
  border: none;
  padding: 4px 8px;

  &:focus { box-shadow: none; }
}

/* --- Mobile (< 992px) ---------------------------------------------------- */
@media (max-width: 991.98px) {
  .site-navbar { background: var(--color-white-96); }
  .site-navbar .navbar-collapse { padding-bottom: var(--space-4); }
  .site-navbar__link { padding: 10px 0; }
  .site-navbar__link:hover,
  .site-navbar__link:focus { background-color: transparent; }
  .site-navbar__cta { margin-top: var(--space-3); width: fit-content; }
}
/* ==========================================================================
   Component: Footer — dark navy gradient, 4 columns
   ========================================================================== */

.site-footer {
  background: linear-gradient(168.2deg, #141240 35.5%, #234494 70.8%, #2053cf 83.2%);  /* v1.1 #_Footer_1 */
  color: var(--color-white);
  padding-top: var(--space-20);
  padding-bottom: var(--space-6);
}

.site-footer__logo {
  height: 34px;
  width: auto;
  margin-bottom: var(--space-5);
}

.site-footer__tagline {
  font-size: 16px;          /* v1.1 #Address_Text_3 16/400 */
  line-height: 1.7;
  color: var(--color-white-60);
  max-width: 320px;
}

/* --- Column titles ------------------------------------------------------ */
.site-footer__title {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: var(--space-5);
}

/* --- Nav list ----------------------------------------------------------- */
.site-footer__nav {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.site-footer__link {
  color: var(--color-white-70);
  font-size: 16px;          /* v1.1 #Title_59 16/400 */
  transition: color var(--transition-fast);

  &:hover,
  &:focus { color: var(--color-white); }
}

/* --- Contact ------------------------------------------------------------ */
.site-footer__contact {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.site-footer__contact-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  font-size: 16px;          /* v1.1 #Address_Text 16/400 */
  color: var(--color-white-70);
  line-height: 1.5;
}

.site-footer__icon {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  margin-top: 2px;
  color: var(--color-brand-light);
}

/* --- Social ------------------------------------------------------------- */
.site-footer__social {
  display: flex;
  gap: var(--space-3);
}

.site-footer__social-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background-color: var(--color-white-10);
  color: var(--color-white);
  transition: background-color var(--transition-base);

  & svg { width: 18px; height: 18px; }
  &:hover,
  &:focus { background-color: var(--color-brand-light); }
}

/* --- Bottom ------------------------------------------------------------- */
.site-footer__bottom {
  margin-top: var(--space-16);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-white-12);
  text-align: center;
}

.site-footer__copyright {
  font-size: var(--font-size-sm);
  color: var(--color-white-60);
  margin: 0;
}
/* ==========================================================================
   Component: Buttons (.btn-wihub)
   ========================================================================== */

.btn-wihub {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-family);
  font-size: 16px;
  font-weight: 700;
  line-height: 1;
  padding: 15px 26px;
  border-radius: 14px;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color var(--transition-base),
              border-color var(--transition-base),
              color var(--transition-base),
              transform var(--transition-base);

  &:hover .btn-wihub__arrow { transform: translateX(3px); }
}

.btn-wihub__arrow {
  display: inline-flex;
  align-items: center;
  transition: transform var(--transition-base);
}

/* --- Primary (blue gradient) -------------------------------------------- */
.btn-wihub--primary {
  background-image: var(--gradient-primary);
  border-color: var(--color-brand-light);
  color: var(--color-white);
  box-shadow: var(--shadow-btn-primary);

  /* hover: xanh NHẠT HƠN (lighten, không darken) */
  &:hover,
  &:focus {
    background-image: var(--gradient-primary-hover);
    color: var(--color-white);
  }
}

/* --- Light (nền trắng, viền navy, chữ navy) — v1.1 #Button_24 / #Button_31 -- */
.btn-wihub--light {
  background-image: none;
  background-color: var(--color-white);
  border-color: var(--color-brand-dark);
  color: var(--color-brand-dark);
  border-radius: 12px;       /* v1.1 #Button_24/#Button_31 radius 12px */
  box-shadow: var(--shadow-btn);

  /* hover NỀN xanh nhẹ (giống nav link), giữ chữ/viền navy */
  &:hover,
  &:focus {
    background-color: #e8f0fb;
    color: var(--color-brand-dark);
    border-color: var(--color-brand-dark);
  }
}

/* --- Outline white (translucent, on dark/media) ------------------------- */
.btn-wihub--outline-white {
  background-color: var(--color-white-20);
  border-color: var(--color-white);
  color: var(--color-white);
  backdrop-filter: blur(2px);

  &:hover,
  &:focus {
    background-color: var(--color-white);
    color: var(--color-brand-dark);
  }
}

/* --- Outline dark (on light bg) ----------------------------------------- */
.btn-wihub--outline-dark {
  background-color: transparent;
  border-color: var(--color-border-divider);
  color: var(--color-text-main);

  &:hover,
  &:focus {
    border-color: var(--color-brand-default);
    color: var(--color-brand-default);
  }
}

/* --- Ghost (text + arrow, on light) ------------------------------------- */
.btn-wihub--ghost {
  background-color: transparent;
  border-color: transparent;
  color: var(--color-brand-default);
  padding-left: 0;
  padding-right: 0;

  &:hover { color: var(--color-brand-dark); }
}

/* --- Ghost light pill ("Tìm Hiểu Thêm") — v1.1 #Button_Text_33/34/35/41:
   text 14px/600, line-height 100%, radius 6px, bg rgba(255,255,255,.2), padding 6px 12px.
   Hover: NỀN TRẮNG trượt ngang (left→right) lấp đầy, chữ chuyển navy (reaction 2257: ease-out .333s) */
.btn-ghost-light {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  font-size: 14px;
  font-weight: 600;
  line-height: 1;
  color: var(--color-white);
  background-color: var(--color-white-20);
  border-radius: 6px;
  text-decoration: none;
  transition: color 0.333s ease-out;

  &::before {
    content: "";
    position: absolute;
    inset: 0;
    z-index: -1;
    background-color: var(--color-white);
    transform: translateX(-101%);
    transition: transform 0.333s ease-out;
  }
  &:hover,
  &:focus { color: var(--color-brand-dark); }
  &:hover::before,
  &:focus::before { transform: translateX(0); }
  &:hover .btn-ghost-light__arrow { transform: translateX(3px); }
}
.btn-ghost-light__arrow { transition: transform var(--transition-base); }

/* --- Ghost white (text + arrow, on dark) -------------------------------- */
.btn-wihub--ghost-white {
  background-color: var(--color-white-10);
  border-color: var(--color-white-20);
  color: var(--color-white);

  &:hover,
  &:focus {
    background-color: var(--color-white-20);
    color: var(--color-white);
  }
}
/* ==========================================================================
   Component: Contact — "Vì Một Việt Nam Khoẻ Mạnh Hơn"
   Dùng chung cho mọi page (1 nguồn duy nhất). Giá trị trích từ v1.1.
   ========================================================================== */
.contact-section {
  position: relative;
  padding: 120px 0;            /* v1.1 #Gradient_Color_1 padding 120px 48px */
  overflow: hidden;
  background-color: var(--color-brand-dark);
}

/* nền cyan (ảnh) → navy đáy theo v1.1 (cyan top, navy bottom) */
.contact-section__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 0;
}

.contact-section__overlay {
  position: absolute;
  inset: 0;
  z-index: 1;
  /* v1.1 #Gradient_Color_1: periwinkle 25% (trên) → navy (đáy) */
  background-image: linear-gradient(178.6deg, rgba(111, 107, 200, 0.25) 59.5%, #141240 94.8%);
}

.contact-section__inner { position: relative; z-index: 2; }

.contact-section__title {
  font-size: 46px;             /* v1.1 #Headline_1 46/800/130% */
  font-weight: 800;
  line-height: 1.3;
  color: var(--color-white);
  margin-bottom: 24px;         /* v1.1 #Text_Section_Container row-gap 24 */

  & em {
    font-style: normal;
    color: var(--color-white);   /* v1.1: tiêu đề TRẮNG toàn bộ, không accent */
  }
}

.contact-section__desc {
  font-size: 18px;             /* v1.1 #Subheadline_1 18/400/160% */
  font-weight: 400;
  line-height: 1.6;
  color: var(--color-white-80);
  max-width: 480px;
  margin-bottom: 0;
}

/* --- Form --- */
.contact-form {
  background-color: var(--color-white);
  border-radius: 16px;
  padding: 32px;
  box-shadow: 0 20px 60px rgba(12, 12, 13, 0.20);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.contact-form__field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.contact-form__label {
  font-size: 16px;             /* v1.1 #Name_Label 16/500 */
  font-weight: 500;
  color: var(--color-text-main);
}

.contact-form__input {
  width: 100%;
  padding: 12px 14px;
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  color: var(--color-text-main);
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);

  &::placeholder { color: var(--color-text-placeholder); }
  &:focus {
    outline: none;
    border-color: var(--color-brand-default);
    box-shadow: var(--focus-ring);
  }
}

.contact-form__textarea {
  resize: vertical;
  min-height: 96px;
}

.contact-form__select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8' fill='none'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%237a879a' stroke-width='1.6' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  padding-right: 36px;
}

.contact-form__submit {
  width: 100%;
  justify-content: center;
  margin-top: 8px;

  &:hover,
  &:focus {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(13, 80, 161, 0.35);
  }
}

@media (max-width: 991.98px) {
  .contact-section { padding: 80px 0; }
  .contact-section__title { font-size: 34px; }
}
@media (max-width: 575.98px) {
  .contact-section { padding: 60px 0; }
  .contact-section__title { font-size: 28px; }
  .contact-form { padding: 24px; }
}
/* ==========================================================================
   Component: News Card — dùng chung cho index (home-news) · news · news-article
   Thiết kế chuẩn (trích v1.1): card inset 7px, radius 24, hover viền xanh.
   1 nguồn duy nhất → không phải đồng bộ tay 3 file nữa.
   ========================================================================== */
.news-card {
  display: flex;
  flex-direction: column;
  height: 100%;
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 24px;          /* v1.1 #_Home_News_Article 24px */
  padding: 7px;                 /* ảnh + nội dung INSET 7px */
  overflow: hidden;
  text-decoration: none;
  color: inherit;
  transition: box-shadow var(--transition-base), transform var(--transition-base), border-color var(--transition-base);

  &:hover,
  &:focus-visible {
    box-shadow: 0 8px 28px rgba(36, 63, 97, 0.16);
    transform: translateY(-3px);
    border-color: var(--color-brand-default);   /* hover viền xanh (v1.1) */
    color: inherit;
  }
}

.news-card__media {
  position: relative;
  width: 100%;
  aspect-ratio: 380 / 220;
  border-radius: 16px;          /* ảnh bo tròn cả 4 góc (inset) */
  overflow: hidden;
  background-color: var(--color-bg-icon);
}
.news-card__image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.news-card__body {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 20px 16px;           /* v1.1 #Article_Content 20px 16px */
  flex: 1 1 auto;
}

/* --- Category badge ------------------------------------------------------- */
.news-card__category {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  align-self: flex-start;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.2;
}
.news-card__category-icon { display: inline-flex; }
.news-card__category svg { width: 14px; height: 14px; }   /* hỗ trợ cả markup icon trực tiếp */
.news-card__category--news { background-color: rgba(13, 80, 161, 0.08); color: var(--color-brand-default); }
.news-card__category--research { background-color: rgba(26, 164, 221, 0.10); color: var(--color-brand-light); }
.news-card__category--share { background-color: rgba(20, 18, 64, 0.08); color: var(--color-brand-dark); }

/* --- Text ---------------------------------------------------------------- */
.news-card__title {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  line-height: 1.35;
  color: var(--color-text-main);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.news-card__excerpt {
  margin: 0;
  font-size: 14px;
  line-height: 1.55;
  color: var(--color-text-secondary);
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* --- Author -------------------------------------------------------------- */
.news-card__author {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px solid var(--color-border);
}
.news-card__author-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
}
.news-card__author-info { display: flex; flex-direction: column; gap: 2px; }
.news-card__author-name {
  margin: 0;
  font-size: 13px;
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-text-main);
}
.news-card__author-date {
  margin: 0;
  font-size: 12px;
  line-height: 1.2;
  color: var(--color-text-tertiary);
}

@media (min-width: 768px) {
  .news-card__title { font-size: 17px; }
}


/* ==========================================================================
   Scroll reveal — nội dung section fade + trượt lên khi vào viewport.
   JS (main.js) tự gắn [data-reveal] + thêm .reveal-ready vào <html> (chống FOUC),
   IntersectionObserver thêm .is-visible. Tôn trọng prefers-reduced-motion.
   ========================================================================== */
@media (prefers-reduced-motion: no-preference) {
  html.reveal-ready [data-reveal] {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.7s cubic-bezier(0.22, 0.61, 0.36, 1),
                transform 0.7s cubic-bezier(0.22, 0.61, 0.36, 1);
    transition-delay: var(--reveal-delay, 0s);
  }
  html.reveal-ready [data-reveal].is-visible {
    opacity: 1;
    transform: none;
  }
}