/* ============================================================
   KINETIC — lõi giao diện dùng chung cho bản D (tối) và bản E (sáng).
   File này KHÔNG chứa màu cụ thể: mọi màu đều đi qua biến, do
   theme-dark.css / theme-light.css nạp trước quyết định.
   ============================================================ */

/* ---------- Token không phụ thuộc tông màu ---------- */
:root {
  --s1: 4px;  --s2: 8px;  --s3: 12px; --s4: 16px;
  --s5: 24px; --s6: 32px; --s7: 48px; --s8: 64px; --s9: 96px;

  --shell:  1440px;
  --gutter: 24px;

  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;

  --ease: cubic-bezier(.2, .7, .2, 1);
}

@media (min-width: 768px) { :root { --gutter: 40px; } }

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, svg, video { display: block; max-width: 100%; }
img { height: auto; }
a { color: inherit; text-decoration: none; }
button, input, textarea, select { font: inherit; color: inherit; }

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

.skip {
  position: absolute; left: var(--s4); top: -100px; z-index: 200;
  background: var(--accent); color: var(--accent-on);
  padding: var(--s3) var(--s5); font: 700 12px/1 var(--mono);
  letter-spacing: .08em; text-transform: uppercase;
  transition: top .2s var(--ease);
}
.skip:focus { top: var(--s4); }

/* ---------- Khung ---------- */
.shell {
  width: 100%; max-width: var(--shell);
  margin-inline: auto; padding-inline: var(--gutter);
}
.section { padding-block: var(--s8); border-top: 1px solid var(--line); }
@media (min-width: 768px) { .section { padding-block: var(--s9); } }
.section--flush { border-top: 0; }

/* ---------- Chữ ---------- */
.eyebrow {
  font: 700 11px/1 var(--mono);
  letter-spacing: .16em; text-transform: uppercase;
  color: var(--accent-text);
  display: inline-flex; align-items: center; gap: var(--s2);
}
.eyebrow::before { content: ""; width: 18px; height: 1px; background: currentColor; }
.eyebrow--steel { color: var(--steel); }

h1, h2, h3, h4 { font-weight: 700; letter-spacing: -.025em; line-height: 1.08; text-wrap: balance; }

.h-display { font-size: clamp(38px, 6.4vw, 82px); }
.h-1 { font-size: clamp(32px, 4.4vw, 56px); }
.h-2 { font-size: clamp(24px, 2.6vw, 36px); line-height: 1.15; }
.h-3 { font-size: 20px; line-height: 1.25; letter-spacing: -.015em; }

.lede {
  font-size: clamp(17px, 1.5vw, 20px); line-height: 1.6;
  color: var(--ink-soft); max-width: 60ch; text-wrap: pretty;
}
.prose { color: var(--ink-soft); max-width: 68ch; text-wrap: pretty; }

.tag {
  font: 500 12px/1 var(--mono); letter-spacing: .06em;
  color: var(--ink-faint); text-transform: uppercase;
}
.tag--acid  { color: var(--accent-text); }
.tag--steel { color: var(--steel); }

.num {
  font: 700 clamp(30px, 3.6vw, 46px)/1 var(--mono);
  letter-spacing: -.03em; font-variant-numeric: tabular-nums;
  color: var(--ink);
}

/* ---------- Nút ---------- */
.btn {
  display: inline-flex; align-items: center; gap: var(--s2);
  padding: 14px var(--s5);
  font: 700 12px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase;
  border: 1px solid transparent; cursor: pointer;
  transition: background-color .18s var(--ease), border-color .18s var(--ease), color .18s var(--ease);
}
.btn svg { width: 15px; height: 15px; flex: none; }

.btn--primary { background: var(--accent); color: var(--accent-on); }
.btn--primary:hover { background: var(--accent-dim); }

.btn--ghost { border-color: var(--line-strong); color: var(--ink); }
.btn--ghost:hover { border-color: var(--ink); background: var(--wash); }

/* nút đặt trên dải CTA (nền accent) */
.btn--onlight { background: var(--cta-btn-bg); color: var(--cta-btn-ink); }
.btn--onlight:hover { background: var(--cta-btn-bg-hover); }

/* ---------- Điều hướng ---------- */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(14px) saturate(150%);
  border-bottom: 1px solid var(--line);
}
.nav__inner { display: flex; align-items: center; justify-content: space-between; gap: var(--s5); height: 68px; }
.nav__brand {
  display: inline-flex; align-items: baseline; gap: var(--s2);
  font-weight: 800; font-size: 17px; letter-spacing: -.02em; white-space: nowrap;
}
.nav__brand span { font: 500 10px/1 var(--mono); letter-spacing: .14em; color: var(--accent-text); }

.nav__links { display: none; align-items: center; gap: var(--s6); }
@media (min-width: 1024px) { .nav__links { display: flex; } }

.nav__link {
  position: relative; font-size: 14px; font-weight: 500;
  color: var(--ink-soft); padding-block: var(--s2);
  transition: color .18s var(--ease); white-space: nowrap;
}
.nav__link:hover { color: var(--ink); }
.nav__link::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -1px;
  height: 2px; background: var(--accent-text);
  transform: scaleX(0); transform-origin: left;
  transition: transform .22s var(--ease);
}
.nav__link:hover::after { transform: scaleX(.4); }
.nav__link[aria-current="page"] { color: var(--ink); }
.nav__link[aria-current="page"]::after { transform: scaleX(1); }

.nav__cta { display: none; }
@media (min-width: 1024px) { .nav__cta { display: inline-flex; } }

.nav__burger {
  display: inline-flex; align-items: center; justify-content: center;
  width: 42px; height: 42px; background: none;
  border: 1px solid var(--line-strong); cursor: pointer;
}
@media (min-width: 1024px) { .nav__burger { display: none; } }
.nav__burger svg { width: 18px; height: 18px; }

.drawer {
  position: fixed; inset: 0; z-index: 150;
  background: var(--bg); padding: var(--s5) var(--gutter);
  display: flex; flex-direction: column; gap: var(--s2);
  transform: translateX(100%); transition: transform .3s var(--ease);
  overflow-y: auto;
}
.drawer[data-open="true"] { transform: none; }
.drawer__top { display: flex; align-items: center; justify-content: space-between; margin-bottom: var(--s5); }
.drawer__link {
  padding: var(--s4) 0; border-bottom: 1px solid var(--line);
  font-size: 19px; font-weight: 600;
  display: flex; align-items: center; justify-content: space-between;
}
.drawer__link[aria-current="page"] { color: var(--accent-text); }

/* ---------- Hero ---------- */
.hero { position: relative; overflow: hidden; background: var(--bg-inset); isolation: isolate; }
.hero__media { position: absolute; inset: 0; z-index: -2; }
.hero__media img { width: 100%; height: 100%; object-fit: cover; opacity: var(--hero-img-opacity); }
.hero__scrim {
  position: absolute; inset: 0; z-index: -1;
  background:
    linear-gradient(180deg, var(--scrim-top) 0%, var(--scrim-mid) 40%, var(--bg) 100%),
    linear-gradient(90deg, var(--scrim-left) 8%, var(--scrim-center) 55%, var(--scrim-right) 100%);
}
.grid-veil {
  position: absolute; inset: 0; pointer-events: none; z-index: -1;
  background-image:
    linear-gradient(var(--veil) 1px, transparent 1px),
    linear-gradient(90deg, var(--veil) 1px, transparent 1px);
  background-size: 72px 72px;
  mask-image: radial-gradient(120% 80% at 20% 0%, #000 30%, transparent 78%);
}
.hero__body { padding-block: var(--s8) var(--s7); }
@media (min-width: 768px) { .hero__body { padding-block: var(--s9) var(--s8); } }

/* ---------- Dải chỉ số ---------- */
.stats {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 1px; background: var(--line); border-block: 1px solid var(--line);
}
@media (min-width: 900px) { .stats { grid-template-columns: repeat(4, 1fr); } }
.stat { background: var(--bg); padding: var(--s6) var(--s5) var(--s6) 0; }
.stat dt { margin-bottom: var(--s3); }
.stat dd { margin: 0; }

/* ---------- Lưới & thẻ ---------- */
.grid { display: grid; gap: var(--s5); }
.grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
@media (min-width: 640px) { .grid--2, .grid--4 { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 900px) {
  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .grid--4 { grid-template-columns: repeat(4, 1fr); }
}

.card {
  display: flex; flex-direction: column;
  background: var(--bg-raised); border: 1px solid var(--line);
  transition: border-color .22s var(--ease), background-color .22s var(--ease), transform .22s var(--ease), box-shadow .22s var(--ease);
}
.card:hover { border-color: var(--line-strong); background: var(--bg-panel); }
a.card:hover { transform: translateY(-3px); border-color: var(--accent-text); box-shadow: var(--lift); }
.card__media { position: relative; aspect-ratio: 4 / 3; overflow: hidden; border-bottom: 1px solid var(--line); }
.card__media img { width: 100%; height: 100%; object-fit: cover; transition: transform .7s var(--ease); }
.card:hover .card__media img { transform: scale(1.05); }
.card__badge {
  position: absolute; left: var(--s3); top: var(--s3);
  background: var(--badge-bg); color: var(--badge-ink);
  backdrop-filter: blur(4px); border: 1px solid var(--badge-line);
  padding: 5px var(--s2);
  font: 700 10px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase;
}
.card__body { padding: var(--s5); display: flex; flex-direction: column; gap: var(--s3); flex: 1; }
.card__body > .prose { flex: 1; }

.step { position: relative; padding: var(--s6) var(--s5); background: var(--bg-raised); border: 1px solid var(--line); }
.step__n { font: 700 12px/1 var(--mono); letter-spacing: .1em; color: var(--accent-text); margin-bottom: var(--s4); display: block; }
.step::after {
  content: ""; position: absolute; left: 0; top: 0; width: 2px; height: 0;
  background: var(--accent-text); transition: height .3s var(--ease);
}
.step:hover::after { height: 100%; }

/* ---------- Bảng thông số ---------- */
.spec { width: 100%; border-collapse: collapse; font-size: 15px; }
.spec caption { text-align: left; padding-bottom: var(--s4); }
.spec th, .spec td { text-align: left; padding: var(--s3) var(--s4); border-bottom: 1px solid var(--line); }
.spec th { font: 700 11px/1.4 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); width: 42%; }
.spec td { font-family: var(--mono); font-variant-numeric: tabular-nums; color: var(--ink); }
.spec tr:hover td, .spec tr:hover th { background: var(--wash-soft); }

/* ---------- Dải CTA ---------- */
.cta { background: var(--accent); color: var(--accent-on); }
.cta__inner { display: flex; flex-direction: column; gap: var(--s5); padding-block: var(--s8); align-items: flex-start; }
@media (min-width: 900px) { .cta__inner { flex-direction: row; align-items: center; justify-content: space-between; } }
.cta h2 { font-size: clamp(26px, 3vw, 40px); }
.cta p { color: var(--cta-ink-soft); max-width: 52ch; margin-top: var(--s3); }

/* ---------- Biểu mẫu ---------- */
.field { display: flex; flex-direction: column; gap: var(--s2); }
.field label { font: 700 11px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); }
.field input, .field textarea, .field select {
  background: var(--input-bg); border: 1px solid var(--line);
  padding: 13px var(--s4); color: var(--ink);
  transition: border-color .18s var(--ease);
}
.field input:focus, .field textarea:focus, .field select:focus { outline: none; border-color: var(--accent-text); }
.field textarea { resize: vertical; min-height: 130px; }

/* ---------- Chân trang ---------- */
.foot { margin-top: auto; border-top: 1px solid var(--line); background: var(--bg-inset); }
.foot__grid { display: grid; gap: var(--s7); padding-block: var(--s8); grid-template-columns: 1fr; }
@media (min-width: 768px) { .foot__grid { grid-template-columns: 2fr 1fr 1fr; } }
.foot__col h4 { font: 700 11px/1 var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: var(--s4); }
.foot__col a { display: block; padding-block: 7px; color: var(--ink-soft); font-size: 15px; transition: color .18s var(--ease); }
.foot__col a:hover { color: var(--accent-text); }
.foot__bar {
  border-top: 1px solid var(--line); padding-block: var(--s5);
  display: flex; flex-wrap: wrap; gap: var(--s4);
  justify-content: space-between; align-items: center;
}

/* ---------- Tiện ích ---------- */
.stack { display: flex; flex-direction: column; }
.row { display: flex; flex-wrap: wrap; align-items: center; }
.gap-2 { gap: var(--s2); } .gap-3 { gap: var(--s3); } .gap-4 { gap: var(--s4); }
.gap-5 { gap: var(--s5); } .gap-6 { gap: var(--s6); } .gap-7 { gap: var(--s7); }
.mt-3 { margin-top: var(--s3); } .mt-4 { margin-top: var(--s4); }
.mt-5 { margin-top: var(--s5); } .mt-6 { margin-top: var(--s6); } .mt-7 { margin-top: var(--s7); }
.divider { height: 1px; background: var(--line); border: 0; }

.crumbs { display: flex; align-items: center; gap: var(--s2); padding-top: var(--s5); }
.crumbs a, .crumbs span { font: 500 12px/1 var(--mono); letter-spacing: .06em; }
.crumbs a { color: var(--ink-faint); }
.crumbs a:hover { color: var(--accent-text); }
.crumbs span { color: var(--ink-soft); }

/* ---------- Chuyển động ---------- */
[data-reveal] {
  opacity: 0; transform: translateY(18px);
  transition: opacity .6s var(--ease), transform .6s var(--ease);
}
[data-reveal].is-in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
}