:root {
  --brand: #FF6B35;
  --brand-2: #FFB347;
  --brand-soft: rgba(255, 107, 53, 0.12);
  --accent: #3A7BD5;
  --accent-2: #00D2FF;
  --violet: #8E2DE2;
  --violet-2: #4A00E0;
  --bg: #FFF8F4;
  --bg-elev: #FFFFFF;
  --bg-soft: #FFF1E9;
  --text: #241A14;
  --text-2: #5C4A40;
  --text-3: #8A756A;
  --border: rgba(120, 80, 60, 0.14);
  --border-strong: rgba(120, 80, 60, 0.24);
  --shadow-sm: 0 2px 8px rgba(80, 40, 20, 0.06);
  --shadow: 0 10px 30px rgba(80, 40, 20, 0.10);
  --shadow-lg: 0 24px 60px rgba(80, 40, 20, 0.16);
  --glass: rgba(255, 255, 255, 0.72);
  --glass-border: rgba(255, 255, 255, 0.6);
  --radius-sm: 10px;
  --radius: 18px;
  --radius-lg: 28px;
  --radius-pill: 999px;
  --header-h: 72px;
  --maxw: 1200px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --font: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

[data-theme="dark"] {
  --bg: #14100E;
  --bg-elev: #1E1815;
  --bg-soft: #261E1A;
  --text: #F6EDE7;
  --text-2: #CBB8AC;
  --text-3: #9C877A;
  --border: rgba(255, 220, 200, 0.12);
  --border-strong: rgba(255, 220, 200, 0.22);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 24px 60px rgba(0, 0, 0, 0.6);
  --glass: rgba(30, 24, 21, 0.68);
  --glass-border: rgba(255, 220, 200, 0.14);
  --brand-soft: rgba(255, 107, 53, 0.18);
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 16px);
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
  background-image:
    radial-gradient(900px 480px at 8% -6%, var(--brand-soft), transparent 60%),
    radial-gradient(760px 420px at 100% 0%, rgba(58, 123, 213, 0.10), transparent 62%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
  transition: background-color 0.35s var(--ease), color 0.35s var(--ease);
}

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

a {
  color: var(--brand);
  text-decoration: none;
  transition: color 0.25s var(--ease), opacity 0.25s var(--ease);
}

a:hover {
  color: #E4531F;
}

[data-theme="dark"] a:hover {
  color: var(--brand-2);
}

ul,
ol {
  padding-left: 1.25em;
}

h1, h2, h3, h4 {
  line-height: 1.3;
  color: var(--text);
  font-weight: 700;
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(1.7rem, 3.4vw, 2.5rem); }
h2 { font-size: clamp(1.4rem, 2.6vw, 1.9rem); }
h3 { font-size: clamp(1.12rem, 1.8vw, 1.35rem); }
h4 { font-size: 1.05rem; }

p { color: var(--text-2); }

strong { color: var(--text); font-weight: 700; }

:focus-visible {
  outline: 3px solid var(--brand);
  outline-offset: 3px;
  border-radius: 6px;
}

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

::selection {
  background: var(--brand);
  color: #fff;
}

/* ============ Header ============ */
#site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--glass);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
  backdrop-filter: saturate(180%) blur(18px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow 0.3s var(--ease), background 0.3s var(--ease);
}

#site-header.is-scrolled {
  box-shadow: var(--shadow);
}

.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 18px;
}

.brand a {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text);
}

.brand-logo {
  display: inline-flex;
  flex: 0 0 auto;
  border-radius: 12px;
  box-shadow: 0 6px 18px rgba(255, 107, 53, 0.35);
  transition: transform 0.35s var(--ease);
}

.brand a:hover .brand-logo {
  transform: rotate(-6deg) scale(1.06);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
}

.brand-text strong {
  font-size: 1.05rem;
  letter-spacing: 0.01em;
}

.brand-text small {
  font-size: 0.72rem;
  color: var(--text-3);
  font-weight: 400;
}

#main-nav {
  margin-left: auto;
}

#main-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}

#main-nav a {
  display: block;
  padding: 8px 12px;
  font-size: 0.9rem;
  color: var(--text-2);
  border-radius: var(--radius-pill);
  position: relative;
  transition: color 0.25s var(--ease), background 0.25s var(--ease);
}

#main-nav a::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--brand), var(--brand-2));
  border-radius: 2px;
  transform: translateX(-50%);
  transition: width 0.3s var(--ease);
}

#main-nav a:hover {
  color: var(--brand);
  background: var(--brand-soft);
}

#main-nav a:hover::after {
  width: 60%;
}

.header-tools {
  display: flex;
  align-items: center;
  gap: 10px;
}

#site-search {
  display: flex;
  align-items: center;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  padding: 3px 3px 3px 14px;
  transition: border-color 0.25s var(--ease), box-shadow 0.25s var(--ease);
}

#site-search:focus-within {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-soft);
}

#search-input {
  border: 0;
  background: transparent;
  color: var(--text);
  font-family: inherit;
  font-size: 0.88rem;
  width: 150px;
  padding: 6px 0;
  outline: none;
}

#search-input::placeholder {
  color: var(--text-3);
}

#site-search button {
  border: 0;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  color: #fff;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  border-radius: var(--radius-pill);
  padding: 6px 14px;
  transition: transform 0.25s var(--ease), filter 0.25s var(--ease);
}

#site-search button:hover {
  transform: translateY(-1px);
  filter: brightness(1.06);
}

#theme-toggle,
#menu-toggle {
  border: 1px solid var(--border);
  background: var(--bg-elev);
  color: var(--text);
  width: 40px;
  height: 40px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1.05rem;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.3s var(--ease), background 0.25s var(--ease), border-color 0.25s var(--ease);
}

#theme-toggle:hover,
#menu-toggle:hover {
  transform: translateY(-2px) rotate(8deg);
  border-color: var(--brand);
  background: var(--brand-soft);
}

#menu-toggle {
  display: none;
}

/* ============ Layout ============ */
main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px 40px;
}

section {
  margin: 48px 0;
  scroll-margin-top: calc(var(--header-h) + 16px);
}

/* ============ Hero ============ */
#hero {
  margin-top: 28px;
  display: grid;
  gap: 28px;
}

.hero-slider {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  isolation: isolate;
}

.hero-slider .slide {
  display: none;
  position: relative;
  animation: fadeSlide 0.7s var(--ease);
}

.hero-slider .slide.is-active {
  display: block;
}

@keyframes fadeSlide {
  from { opacity: 0; transform: scale(1.02); }
  to { opacity: 1; transform: scale(1); }
}

.hero-slider figure {
  margin: 0;
  aspect-ratio: 1200 / 360;
  min-height: 200px;
}

.hero-slider figure svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.slide-caption {
  position: absolute;
  inset: auto 0 0 0;
  padding: 26px 28px 30px;
  background: linear-gradient(to top, rgba(20, 10, 5, 0.72), rgba(20, 10, 5, 0.12) 62%, transparent);
  color: #fff;
}

.slide-caption h2 {
  margin: 0 0 8px;
  color: #fff;
  font-size: clamp(1.15rem, 2.4vw, 1.6rem);
  text-shadow: 0 2px 14px rgba(0, 0, 0, 0.35);
}

.slide-caption p {
  margin: 0;
  color: rgba(255, 255, 255, 0.92);
  font-size: 0.94rem;
  max-width: 62ch;
}

.slider-dots {
  position: absolute;
  right: 20px;
  bottom: 20px;
  display: flex;
  gap: 8px;
  z-index: 2;
}

.slider-dots button {
  width: 10px;
  height: 10px;
  padding: 0;
  border-radius: 50%;
  border: 0;
  background: rgba(255, 255, 255, 0.45);
  cursor: pointer;
  transition: all 0.3s var(--ease);
}

.slider-dots button[aria-selected="true"] {
  width: 26px;
  border-radius: var(--radius-pill);
  background: #fff;
}

.hero-text {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: clamp(22px, 3.4vw, 40px);
  box-shadow: var(--shadow);
  position: relative;
  overflow: hidden;
}

.hero-text::before {
  content: "";
  position: absolute;
  top: -60px;
  right: -60px;
  width: 220px;
  height: 220px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--brand-soft), transparent 70%);
  pointer-events: none;
}

.hero-text h1 {
  margin: 0 0 14px;
  background: linear-gradient(120deg, var(--brand), #E4531F 45%, var(--brand-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}

.hero-lead {
  font-size: 1.02rem;
  line-height: 1.85;
  margin: 0 0 24px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  margin-bottom: 26px;
}

.stat {
  background: linear-gradient(160deg, var(--bg-soft), var(--bg-elev));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 12px;
  text-align: center;
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease), border-color 0.3s var(--ease);
}

.stat:hover {
  transform: translateY(-4px);
  border-color: var(--brand);
  box-shadow: 0 12px 26px rgba(255, 107, 53, 0.18);
}

.stat .num {
  display: block;
  font-size: clamp(1.3rem, 2.6vw, 1.85rem);
  font-weight: 800;
  color: var(--brand);
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}

.stat .label {
  display: block;
  font-size: 0.78rem;
  color: var(--text-3);
  margin-top: 2px;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 0;
}

.btn-primary,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 26px;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 0.95rem;
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease), filter 0.3s var(--ease);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  color: #fff;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  box-shadow: 0 10px 24px rgba(255, 107, 53, 0.34);
}

.btn-primary:hover {
  color: #fff;
  transform: translateY(-3px);
  box-shadow: 0 16px 32px rgba(255, 107, 53, 0.42);
  filter: brightness(1.05);
}

.btn-secondary {
  color: var(--text);
  background: var(--bg-elev);
  border: 1px solid var(--border-strong);
}

.btn-secondary:hover {
  color: var(--brand);
  transform: translateY(-3px);
  border-color: var(--brand);
  box-shadow: var(--shadow-sm);
}

/* ============ Breadcrumb & TOC ============ */
#breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 0;
  margin: 0;
  font-size: 0.86rem;
  color: var(--text-3);
}

#breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--text-3);
  opacity: 0.6;
}

#toc {
  background: var(--glass);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: var(--shadow-sm);
  margin: 0 0 8px;
}

#toc h2 {
  margin: 0 0 12px;
  font-size: 1rem;
  color: var(--text);
}

#toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 4px 18px;
}

#toc a {
  display: block;
  padding: 5px 0;
  font-size: 0.9rem;
  color: var(--text-2);
  border-bottom: 1px dashed transparent;
  transition: color 0.25s var(--ease), padding-left 0.25s var(--ease);
}

#toc a:hover {
  color: var(--brand);
  padding-left: 6px;
}

/* ============ Sections & cards ============ */
section > h2 {
  position: relative;
  padding-bottom: 14px;
  margin-bottom: 20px;
}

section > h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 64px;
  height: 4px;
  border-radius: 4px;
  background: linear-gradient(90deg, var(--brand), var(--brand-2));
}

#intro,
#products,
#solutions,
#scenes,
#cases,
#news,
#articles,
#faq,
#howto,
#contact,
#sitemap {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: clamp(22px, 3.2vw, 40px);
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.35s var(--ease), transform 0.35s var(--ease);
}

#intro:hover,
#products:hover,
#solutions:hover,
#scenes:hover,
#cases:hover,
#news:hover,
#articles:hover,
#faq:hover,
#howto:hover,
#contact:hover,
#sitemap:hover {
  box-shadow: var(--shadow);
}

#intro h3,
#products h3,
#solutions h3,
#scenes h3,
#cases h3,
#news h3,
#articles h3,
#faq h3,
#howto h3,
#contact h3 {
  margin-top: 30px;
  padding-left: 14px;
  border-left: 4px solid var(--brand);
}

#intro h4,
#products h4 {
  margin-top: 22px;
  color: var(--brand);
}

#intro ul,
#products ul,
#solutions ul,
#scenes ul,
#howto ul,
#howto ol,
#sitemap ul,
#contact ul,
#links ul {
  color: var(--text-2);
}

#intro li,
#products li,
#solutions li,
#scenes li,
#howto li {
  margin-bottom: 8px;
}

.meta-line {
  font-size: 0.82rem;
  color: var(--text-3);
  margin: 6px 0 12px;
  letter-spacing: 0.01em;
}

/* ============ News ============ */
.news-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 14px;
}

.news-list li {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease), border-color 0.3s var(--ease);
}

.news-list li:hover {
  transform: translateY(-3px);
  border-color: var(--brand);
  box-shadow: var(--shadow-sm);
}

.news-list h3 {
  margin: 0 0 4px;
  padding: 0;
  border: 0;
  font-size: 1.05rem;
}

.news-list h3 a {
  color: var(--text);
}

.news-list h3 a:hover {
  color: var(--brand);
}

.news-list p {
  margin: 0;
  font-size: 0.92rem;
}

/* ============ Articles ============ */
#articles article {
  background: linear-gradient(160deg, var(--bg-soft), var(--bg-elev) 70%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 16px;
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease), border-color 0.3s var(--ease);
}

#articles article:hover {
  transform: translateY(-3px);
  border-color: var(--brand);
  box-shadow: var(--shadow);
}

#articles article h3 {
  margin: 0 0 4px;
  padding: 0;
  border: 0;
  font-size: 1.08rem;
}

#articles article p {
  margin: 0 0 10px;
  font-size: 0.94rem;
}

#articles article p:last-child {
  margin-bottom: 0;
}

#articles article a {
  font-weight: 600;
  font-size: 0.88rem;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

#articles article a::after {
  content: "→";
  transition: transform 0.25s var(--ease);
}

#articles article a:hover::after {
  transform: translateX(4px);
}

/* ============ Blockquote ============ */
blockquote {
  margin: 14px 0;
  padding: 16px 20px;
  background: var(--brand-soft);
  border-left: 4px solid var(--brand);
  border-radius: 0 var(--radius) var(--radius) 0;
  position: relative;
  transition: transform 0.3s var(--ease);
}

blockquote:hover {
  transform: translateX(4px);
}

blockquote p {
  margin: 0;
  color: var(--text-2);
  font-style: italic;
}

/* ============ FAQ ============ */
#faq details {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4px 20px;
  margin-bottom: 12px;
  transition: border-color 0.3s var(--ease), box-shadow 0.3s var(--ease), background 0.3s var(--ease);
}

#faq details:hover {
  border-color: var(--brand);
}

#faq details[open] {
  border-color: var(--brand);
  box-shadow: var(--shadow-sm);
  background: var(--bg-elev);
}

#faq summary {
  cursor: pointer;
  list-style: none;
  padding: 14px 30px 14px 0;
  font-weight: 600;
  color: var(--text);
  position: relative;
  transition: color 0.25s var(--ease);
}

#faq summary::-webkit-details-marker {
  display: none;
}

#faq summary::after {
  content: "+";
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.35rem;
  font-weight: 400;
  color: var(--brand);
  transition: transform 0.3s var(--ease);
}

#faq details[open] summary::after {
  transform: translateY(-50%) rotate(45deg);
}

#faq summary:hover {
  color: var(--brand);
}

#faq details p {
  margin: 0 0 16px;
  font-size: 0.94rem;
  animation: fadeIn 0.35s var(--ease);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============ HowTo ordered steps ============ */
#howto ol {
  counter-reset: step;
  list-style: none;
  padding: 0;
}

#howto ol > li {
  counter-increment: step;
  position: relative;
  padding: 12px 16px 12px 52px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
  transition: transform 0.3s var(--ease), border-color 0.3s var(--ease);
}

#howto ol > li:hover {
  transform: translateX(4px);
  border-color: var(--brand);
}

#howto ol > li::before {
  content: counter(step);
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  color: #fff;
  font-size: 0.82rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 10px rgba(255, 107, 53, 0.3);
}

/* ============ Contact ============ */
#contact address {
  font-style: normal;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 16px 0;
}

#contact address ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

#contact address li {
  padding: 6px 0;
  border-bottom: 1px dashed var(--border);
  font-size: 0.94rem;
}

#contact address li:last-child {
  border-bottom: 0;
}

#contact address strong {
  color: var(--text);
  margin-right: 6px;
}

/* ============ Sitemap ============ */
#sitemap ul {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
  gap: 8px;
}

#sitemap li a {
  display: block;
  padding: 9px 14px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  color: var(--text-2);
  transition: all 0.25s var(--ease);
}

#sitemap li a:hover {
  color: #fff;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  border-color: transparent;
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(255, 107, 53, 0.28);
}

/* ============ Footer ============ */
#site-footer {
  margin-top: 60px;
  background: linear-gradient(170deg, var(--bg-soft), var(--bg-elev));
  border-top: 1px solid var(--border);
  padding: 48px 20px 32px;
}

#site-footer section {
  max-width: var(--maxw);
  margin: 0 auto 28px;
  padding: 0;
}

#site-footer h2 {
  font-size: 1.05rem;
  margin: 0 0 12px;
  padding-bottom: 10px;
  position: relative;
}

#site-footer h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 40px;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--brand), var(--brand-2));
}

#site-footer p {
  font-size: 0.9rem;
  margin: 0;
  max-width: 78ch;
}

#links ul {
  list-style: none;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

#links a {
  display: inline-block;
  padding: 8px 16px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  font-size: 0.86rem;
  color: var(--text-2);
  transition: all 0.25s var(--ease);
}

#links a:hover {
  color: var(--brand);
  border-color: var(--brand);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

#copyright {
  border-top: 1px solid var(--border);
  padding-top: 22px;
  margin-bottom: 0;
}

#copyright p {
  color: var(--text-3);
  font-size: 0.84rem;
  text-align: center;
}

/* ============ Back to top ============ */
#back-to-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 90;
  width: 48px;
  height: 48px;
  border: 0;
  border-radius: 50%;
  cursor: pointer;
  color: #fff;
  font-size: 1.2rem;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  box-shadow: 0 10px 26px rgba(255, 107, 53, 0.4);
  opacity: 0;
  visibility: hidden;
  transform: translateY(16px) scale(0.9);
  transition: opacity 0.35s var(--ease), transform 0.35s var(--ease), visibility 0.35s, box-shadow 0.3s var(--ease);
}

#back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

#back-to-top:hover {
  transform: translateY(-4px) scale(1.06);
  box-shadow: 0 16px 34px rgba(255, 107, 53, 0.5);
}

/* ============ Scroll reveal ============ */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
  will-change: opacity, transform;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

/* ============ Responsive ============ */
@media (max-width: 1080px) {
  #main-nav ul { gap: 0; }
  #main-nav a { padding: 8px 9px; font-size: 0.85rem; }
  #search-input { width: 120px; }
}

@media (max-width: 900px) {
  :root { --header-h: 64px; }

  .header-inner { gap: 12px; }

  #menu-toggle { display: inline-flex; }

  #main-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    margin: 0;
    background: var(--glass);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s var(--ease);
  }

  #main-nav.is-open {
    max-height: 70vh;
    overflow-y: auto;
  }

  #main-nav ul {
    flex-direction: column;
    padding: 12px 20px 20px;
    gap: 2px;
  }

  #main-nav a {
    padding: 12px 14px;
    font-size: 0.98rem;
    border-radius: var(--radius-sm);
  }

  #main-nav a::after { display: none; }

  #site-search { display: none; }

  .hero-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .hero-slider figure { aspect-ratio: 16 / 9; }

  #hero { margin-top: 18px; }
}

@media (max-width: 640px) {
  body { font-size: 15px; line-height: 1.72; }

  main { padding: 0 14px 32px; }

  .header-inner { padding: 0 14px; }

  .brand-text small { display: none; }

  .brand-text strong { font-size: 0.98rem; }

  .brand-logo svg { width: 34px; height: 34px; }

  section { margin: 32px 0; }

  #intro,
  #products,
  #solutions,
  #scenes,
  #cases,
  #news,
  #articles,
  #faq,
  #howto,
  #contact,
  #sitemap {
    padding: 20px 16px;
    border-radius: var(--radius);
  }

  .hero-text { padding: 20px 18px; border-radius: var(--radius); }

  .hero-slider { border-radius: var(--radius); }

  .slide-caption { padding: 18px 16px 22px; }

  .slide-caption p { font-size: 0.86rem; }

  .slider-dots { right: 12px; bottom: 12px; }

  .hero-stats { gap: 8px; }

  .stat { padding: 12px 8px; }

  .stat .label { font-size: 0.72rem; }

  .btn-primary,
  .btn-secondary { flex: 1 1 auto; padding: 12px 18px; font-size: 0.9rem; }

  #toc { padding: 16px; }

  #toc ul { grid-template-columns: 1fr 1fr; gap: 2px 12px; }

  #toc a { font-size: 0.84rem; }

  #articles article,
  .news-list li { padding: 16px; }

  #faq details { padding: 2px 14px; }

  #faq summary { font-size: 0.95rem; padding-right: 26px; }

  #sitemap ul { grid-template-columns: 1fr 1fr; }

  #back-to-top { right: 14px; bottom: 14px; width: 44px; height: 44px; }

  #site-footer { padding: 36px 14px 26px; }

  #links ul { gap: 8px; }

  #links a { padding: 7px 13px; font-size: 0.82rem; }
}

@media (max-width: 380px) {
  #toc ul,
  #sitemap ul { grid-template-columns: 1fr; }
  .hero-stats { grid-template-columns: 1fr 1fr; }
}

@media (hover: none) {
  .stat:hover,
  .news-list li:hover,
  #articles article:hover,
  #sitemap li a:hover,
  .btn-primary:hover,
  .btn-secondary:hover {
    transform: none;
  }
}

@media print {
  #site-header,
  #back-to-top,
  #toc,
  .slider-dots,
  #site-footer #links {
    display: none !important;
  }
  body {
    background: #fff;
    color: #000;
  }
  section {
    box-shadow: none;
    border: 1px solid #ddd;
    break-inside: avoid;
  }
  a { color: #000; text-decoration: underline; }
}