:root {
  --primary: #ff5c39;
  --primary-dark: #e64522;
  --primary-light: #ff8a6b;
  --primary-soft: #fff4ef;
  --accent: #ffb59f;
  --accent-soft: #ffe8e0;
  --bg: #fdf8f6;
  --bg-alt: #ffffff;
  --bg-elevated: #ffffff;
  --text: #1f1a17;
  --text-secondary: #5c524c;
  --text-muted: #8a7e77;
  --border: #f0e4de;
  --border-strong: #e5d5cd;
  --shadow-sm: 0 2px 8px rgba(255, 92, 57, 0.06);
  --shadow-md: 0 8px 24px rgba(255, 92, 57, 0.10);
  --shadow-lg: 0 16px 48px rgba(255, 92, 57, 0.14);
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --glass-bg: rgba(255, 255, 255, 0.72);
  --glass-border: rgba(255, 255, 255, 0.55);
  --glass-blur: 18px;
  --transition-fast: 0.18s ease;
  --transition: 0.32s cubic-bezier(0.22, 0.61, 0.36, 1);
  --transition-slow: 0.6s cubic-bezier(0.22, 0.61, 0.36, 1);
  --max-width: 1200px;
  --header-height: 64px;
  --gradient-brand: linear-gradient(135deg, #ff5c39 0%, #ff8a6b 45%, #ffb59f 100%);
  --gradient-hero: linear-gradient(135deg, #fff4ef 0%, #ffe8e0 40%, #ffd9cd 100%);
  --gradient-dark: linear-gradient(135deg, #1a1410 0%, #2a201a 50%, #3a2a22 100%);
}

[data-theme="dark"] {
  --primary: #ff7a5c;
  --primary-dark: #ff5c39;
  --primary-light: #ffa88e;
  --primary-soft: #2a1e18;
  --accent: #ffb59f;
  --accent-soft: #3a2620;
  --bg: #12100e;
  --bg-alt: #1a1614;
  --bg-elevated: #221c18;
  --text: #f5efe9;
  --text-secondary: #c4b8af;
  --text-muted: #8a7e77;
  --border: #2e2620;
  --border-strong: #3d332c;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.5);
  --glass-bg: rgba(34, 28, 24, 0.72);
  --glass-border: rgba(255, 255, 255, 0.08);
  --gradient-hero: linear-gradient(135deg, #1a1410 0%, #2a1e18 40%, #3a2620 100%);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 20px);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
  background-color: var(--bg);
  overflow-x: hidden;
  transition: background-color var(--transition), color var(--transition);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
  position: relative;
}

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

a:focus-visible,
button:focus-visible,
input:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: 4px;
}

ul,
ol {
  list-style: none;
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1.3;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(1.75rem, 4vw, 2.75rem); margin-bottom: 1rem; }
h2 { font-size: clamp(1.4rem, 3vw, 2rem); margin-bottom: 1rem; }
h3 { font-size: clamp(1.15rem, 2.2vw, 1.4rem); margin-bottom: 0.75rem; }
h4 { font-size: 1.1rem; margin-bottom: 0.5rem; }

p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

/* ===== Header ===== */
#site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur)) saturate(180%);
  -webkit-backdrop-filter: blur(var(--glass-blur)) saturate(180%);
  border-bottom: 1px solid var(--glass-border);
  transition: background var(--transition), box-shadow var(--transition), border-color var(--transition);
}

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

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 0.4rem 1.5rem;
  font-size: 0.78rem;
  color: var(--text-muted);
  background: var(--gradient-brand);
  color: #fff;
  flex-wrap: wrap;
}

.top-bar span {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

#site-header nav {
  display: flex;
  align-items: center;
  gap: 1rem;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  flex-wrap: wrap;
}

.logo {
  font-size: 1.4rem;
  font-weight: 800;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
  letter-spacing: -0.02em;
  flex-shrink: 0;
  transition: transform var(--transition);
}

.logo:hover {
  transform: scale(1.05);
}

#site-header nav ul {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex-wrap: wrap;
  flex: 1;
  justify-content: center;
}

#site-header nav ul li a {
  display: inline-block;
  padding: 0.4rem 0.7rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast), background var(--transition-fast), transform var(--transition-fast);
  white-space: nowrap;
}

#site-header nav ul li a:hover {
  color: var(--primary);
  background: var(--primary-soft);
  transform: translateY(-1px);
}

#site-header nav form {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  position: relative;
}

#site-header nav form label {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

#site-header nav form input {
  width: 180px;
  padding: 0.5rem 0.9rem;
  font-size: 0.85rem;
  color: var(--text);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 999px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), width var(--transition);
}

#site-header nav form input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(255, 92, 57, 0.15);
  outline: none;
  width: 220px;
}

#site-header nav form input::placeholder {
  color: var(--text-muted);
}

#site-header nav form button,
#theme-toggle,
#menu-toggle {
  padding: 0.5rem 0.9rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: #fff;
  background: var(--gradient-brand);
  border: none;
  border-radius: 999px;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), filter var(--transition-fast);
  white-space: nowrap;
  font-family: inherit;
}

#site-header nav form button:hover,
#theme-toggle:hover,
#menu-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  filter: brightness(1.05);
}

#theme-toggle {
  background: var(--bg-elevated);
  color: var(--text);
  border: 1px solid var(--border);
}

#theme-toggle:hover {
  background: var(--primary-soft);
  color: var(--primary);
  border-color: var(--primary);
}

#menu-toggle {
  display: none;
}

/* ===== Main ===== */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1.5rem 4rem;
}

/* ===== Breadcrumb ===== */
main > nav[aria-label="面包屑导航"] {
  margin-bottom: 1.5rem;
}

main > nav[aria-label="面包屑导航"] ol {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  flex-wrap: wrap;
}

main > nav[aria-label="面包屑导航"] ol li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

main > nav[aria-label="面包屑导航"] ol li + li::before {
  content: "/";
  color: var(--border-strong);
}

main > nav[aria-label="面包屑导航"] ol li a {
  color: var(--text-muted);
}

main > nav[aria-label="面包屑导航"] ol li a:hover {
  color: var(--primary);
}

main > nav[aria-label="面包屑导航"] ol li[aria-current="page"] {
  color: var(--text-secondary);
  font-weight: 500;
}

/* ===== Sections ===== */
main > section {
  margin-bottom: 3rem;
  padding: 2.5rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition), transform var(--transition), border-color var(--transition), background var(--transition);
  opacity: 0;
  transform: translateY(30px);
  animation: fadeUp 0.7s cubic-bezier(0.22, 0.61, 0.36, 1) forwards;
}

main > section:nth-child(1) { animation-delay: 0.05s; }
main > section:nth-child(2) { animation-delay: 0.1s; }
main > section:nth-child(3) { animation-delay: 0.15s; }
main > section:nth-child(4) { animation-delay: 0.2s; }
main > section:nth-child(5) { animation-delay: 0.25s; }
main > section:nth-child(6) { animation-delay: 0.3s; }
main > section:nth-child(7) { animation-delay: 0.35s; }
main > section:nth-child(8) { animation-delay: 0.4s; }
main > section:nth-child(9) { animation-delay: 0.45s; }
main > section:nth-child(10) { animation-delay: 0.5s; }
main > section:nth-child(11) { animation-delay: 0.55s; }
main > section:nth-child(12) { animation-delay: 0.6s; }
main > section:nth-child(13) { animation-delay: 0.65s; }
main > section:nth-child(14) { animation-delay: 0.7s; }

@keyframes fadeUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

main > section:hover {
  box-shadow: var(--shadow-md);
}

/* ===== Hero ===== */
#hero {
  background: var(--gradient-hero);
  border: none;
  position: relative;
  overflow: hidden;
  padding: 3.5rem 2.5rem;
}

#hero::before {
  content: "";
  position: absolute;
  top: -50%;
  right: -20%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(255, 92, 57, 0.18) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  animation: floatBlob 12s ease-in-out infinite;
}

#hero::after {
  content: "";
  position: absolute;
  bottom: -40%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(255, 181, 159, 0.22) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  animation: floatBlob 15s ease-in-out infinite reverse;
}

@keyframes floatBlob {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(30px, -30px) scale(1.1); }
}

#hero h1 {
  position: relative;
  z-index: 1;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}

#hero > p {
  position: relative;
  z-index: 1;
  max-width: 780px;
  font-size: 1.02rem;
  line-height: 1.85;
}

#hero figure {
  position: relative;
  z-index: 1;
  margin: 2rem 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: var(--bg-elevated);
  transition: transform var(--transition-slow), box-shadow var(--transition-slow);
}

#hero figure:hover {
  transform: translateY(-6px) scale(1.01);
  box-shadow: 0 24px 60px rgba(255, 92, 57, 0.22);
}

#hero figure svg {
  width: 100%;
  height: auto;
  display: block;
}

#hero figcaption {
  padding: 0.75rem 1.25rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-top: 1px solid var(--glass-border);
}

#hero > p:last-child {
  position: relative;
  z-index: 1;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

#hero > p:last-child a {
  display: inline-block;
  padding: 0.6rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: #fff;
  background: var(--gradient-brand);
  border-radius: 999px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), filter var(--transition);
}

#hero > p:last-child a:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  filter: brightness(1.05);
  color: #fff;
}

/* ===== Brand ===== */
#brand aside {
  margin-top: 1.5rem;
  padding: 1.25rem 1.5rem;
  background: var(--primary-soft);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-md);
  transition: transform var(--transition), box-shadow var(--transition);
}

#brand aside:hover {
  transform: translateX(4px);
  box-shadow: var(--shadow-sm);
}

#brand aside h4 {
  color: var(--primary);
}

#brand aside p {
  margin-bottom: 0;
  font-size: 0.9rem;
}

/* ===== Products ===== */
#products ul {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

#products ul li {
  padding: 1.25rem 1.5rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  color: var(--text-secondary);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition), background var(--transition);
  position: relative;
  overflow: hidden;
}

#products ul li::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--gradient-brand);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform var(--transition);
}

#products ul li:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

#products ul li:hover::before {
  transform: scaleY(1);
}

/* ===== Solutions ===== */
#solutions h3 {
  padding-left: 0.75rem;
  border-left: 4px solid var(--primary);
  transition: border-color var(--transition), padding-left var(--transition);
}

#solutions h3:hover {
  padding-left: 1rem;
  border-color: var(--primary-dark);
}

/* ===== Cases ===== */
#cases blockquote {
  margin-top: 1.5rem;
  padding: 1.5rem;
  background: var(--bg-elevated);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  position: relative;
  transition: transform var(--transition), box-shadow var(--transition);
}

#cases blockquote::before {
  content: "\201C";
  position: absolute;
  top: -10px;
  left: 20px;
  font-size: 4rem;
  line-height: 1;
  color: var(--primary);
  opacity: 0.25;
  font-family: Georgia, serif;
}

#cases blockquote:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

#cases blockquote p {
  margin-bottom: 0.75rem;
  font-style: italic;
  color: var(--text-secondary);
}

#cases blockquote p:last-child {
  margin-bottom: 0;
}

/* ===== News ===== */
#news ul {
  display: grid;
  gap: 1rem;
}

#news ul li {
  padding: 1.5rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

#news ul li:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

#news ul li h3 {
  color: var(--text);
  transition: color var(--transition-fast);
}

#news ul li:hover h3 {
  color: var(--primary);
}

#news ul li p:nth-of-type(1) {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

#news ul li p a {
  font-weight: 600;
  font-size: 0.9rem;
}

#news ul li p a::after {
  content: " →";
  transition: transform var(--transition-fast);
  display: inline-block;
}

#news ul li p a:hover::after {
  transform: translateX(4px);
}

/* ===== Articles ===== */
#articles {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.25rem;
  align-items: start;
}

#articles > h2 {
  grid-column: 1 / -1;
}

#articles article {
  padding: 1.5rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

#articles article:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

#articles article h3 {
  font-size: 1.08rem;
  margin-bottom: 0.5rem;
  transition: color var(--transition-fast);
}

#articles article:hover h3 {
  color: var(--primary);
}

#articles article p:nth-of-type(1) {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

#articles article p:nth-of-type(2) {
  font-size: 0.9rem;
  flex: 1;
}

#articles article p:last-child a {
  font-weight: 600;
  font-size: 0.88rem;
}

/* ===== HowTo ===== */
#howto ol {
  counter-reset: step;
  display: grid;
  gap: 0.75rem;
  margin: 1rem 0 1.5rem;
  padding-left: 0;
}

#howto ol li {
  counter-increment: step;
  position: relative;
  padding: 0.9rem 1rem 0.9rem 3.25rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  color: var(--text-secondary);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

#howto ol li::before {
  content: counter(step);
  position: absolute;
  left: 0.9rem;
  top: 50%;
  transform: translateY(-50%);
  width: 1.75rem;
  height: 1.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.82rem;
  font-weight: 700;
  color: #fff;
  background: var(--gradient-brand);
  border-radius: 50%;
  box-shadow: var(--shadow-sm);
}

#howto ol li:hover {
  transform: translateX(4px);
  box-shadow: var(--shadow-sm);
  border-color: var(--primary-light);
}

#howto ul {
  display: grid;
  gap: 0.5rem;
  margin: 0.75rem 0 1.5rem;
}

#howto ul li {
  position: relative;
  padding-left: 1.5rem;
  font-size: 0.95rem;
  color: var(--text-secondary);
}

#howto ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 8px;
  height: 8px;
  background: var(--gradient-brand);
  border-radius: 50%;
}

/* ===== FAQ ===== */
#faq details {
  margin-bottom: 0.75rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: box-shadow var(--transition), border-color var(--transition);
}

#faq details:hover {
  border-color: var(--primary-light);
  box-shadow: var(--shadow-sm);
}

#faq details[open] {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

#faq summary {
  padding: 1.1rem 1.5rem;
  font-weight: 600;
  font-size: 0.98rem;
  color: var(--text);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  transition: background var(--transition-fast), color var(--transition-fast);
  position: relative;
}

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

#faq summary::after {
  content: "+";
  flex-shrink: 0;
  width: 1.5rem;
  height: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  font-weight: 400;
  color: var(--primary);
  background: var(--primary-soft);
  border-radius: 50%;
  transition: transform var(--transition), background var(--transition), color var(--transition);
}

#faq details[open] summary::after {
  content: "−";
  transform: rotate(180deg);
  background: var(--primary);
  color: #fff;
}

#faq summary:hover {
  background: var(--primary-soft);
  color: var(--primary);
}

#faq details p {
  padding: 0 1.5rem 1.25rem;
  font-size: 0.93rem;
  margin-bottom: 0;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== Contact ===== */
#contact address {
  font-style: normal;
  padding: 1.5rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  margin-bottom: 1.5rem;
}

#contact address p {
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

#contact address p:last-child {
  margin-bottom: 0;
}

#contact address a {
  font-weight: 600;
}

/* ===== Sitemap & Links ===== */
#sitemap ul,
#links ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

#sitemap ul li a,
#links ul li a {
  display: inline-block;
  padding: 0.5rem 1rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 999px;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
}

#sitemap ul li a:hover,
#links ul li a:hover {
  color: #fff;
  background: var(--gradient-brand);
  border-color: transparent;
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

/* ===== Legal & Updates ===== */
#legal h3,
#updates h2 {
  margin-top: 1.25rem;
}

#updates p {
  font-size: 0.92rem;
  color: var(--text-muted);
}

/* ===== Footer ===== */
footer {
  background: var(--gradient-dark);
  color: #d4c8bf;
  padding: 3rem 1.5rem 2rem;
  text-align: center;
  margin-top: 2rem;
}

footer p {
  color: #d4c8bf;
  font-size: 0.88rem;
  margin-bottom: 0.6rem;
}

footer p:last-child {
  margin-bottom: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  align-items: center;
}

footer a {
  color: var(--accent);
  transition: color var(--transition-fast);
}

footer a:hover {
  color: #fff;
  text-decoration: underline;
}

/* ===== Back to Top ===== */
#back-to-top {
  position: fixed;
  right: 1.5rem;
  bottom: 1.5rem;
  z-index: 999;
  width: 48px;
  height: 48px;
  padding: 0;
  font-size: 0.72rem;
  font-weight: 600;
  color: #fff;
  background: var(--gradient-brand);
  border: none;
  border-radius: 50%;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px) scale(0.9);
  transition: opacity var(--transition), visibility var(--transition), transform var(--transition), box-shadow var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1.1;
  text-align: center;
  font-family: inherit;
  overflow: hidden;
}

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

#back-to-top:hover {
  transform: translateY(-4px) scale(1.08);
  box-shadow: var(--shadow-lg);
  filter: brightness(1.08);
}

/* ===== Scroll Reveal (JS enhanced) ===== */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  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);
}

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

/* ===== Selection ===== */
::selection {
  background: var(--primary);
  color: #fff;
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: 999px;
  border: 2px solid var(--bg);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--primary-light);
}

/* ===== Responsive: Tablet ===== */
@media (max-width: 1024px) {
  #site-header nav {
    gap: 0.75rem;
  }

  #site-header nav ul li a {
    padding: 0.35rem 0.55rem;
    font-size: 0.82rem;
  }

  #site-header nav form input {
    width: 140px;
  }

  #site-header nav form input:focus {
    width: 170px;
  }

  main > section {
    padding: 2rem 1.75rem;
  }

  #hero {
    padding: 2.75rem 1.75rem;
  }
}

/* ===== Responsive: Mobile ===== */
@media (max-width: 768px) {
  :root {
    --header-height: 56px;
  }

  .top-bar {
    flex-direction: column;
    gap: 0.2rem;
    padding: 0.35rem 1rem;
    font-size: 0.7rem;
    text-align: center;
  }

  .top-bar span {
    white-space: normal;
  }

  #site-header nav {
    padding: 0.6rem 1rem;
    gap: 0.5rem;
    flex-wrap: wrap;
  }

  .logo {
    font-size: 1.2rem;
  }

  #menu-toggle {
    display: inline-block;
    margin-left: auto;
    order: 2;
  }

  #theme-toggle {
    order: 1;
    margin-left: auto;
    padding: 0.45rem 0.75rem;
    font-size: 0.78rem;
  }

  #site-header nav ul {
    order: 10;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 0.15rem;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height var(--transition-slow), opacity var(--transition), margin var(--transition);
    margin-top: 0;
  }

  #site-header nav ul.open {
    max-height: 600px;
    opacity: 1;
    margin-top: 0.5rem;
  }

  #site-header nav ul li a {
    display: block;
    padding: 0.6rem 0.9rem;
    font-size: 0.9rem;
    border-radius: var(--radius-sm);
  }

  #site-header nav form {
    order: 11;
    width: 100%;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height var(--transition-slow), opacity var(--transition), margin var(--transition);
  }

  #site-header nav form.open {
    max-height: 80px;
    opacity: 1;
    margin-top: 0.5rem;
  }

  #site-header nav form input {
    flex: 1;
    width: auto;
  }

  #site-header nav form input:focus {
    width: auto;
  }

  main {
    padding: 1rem 1rem 3rem;
  }

  main > section {
    padding: 1.5rem 1.25rem;
    margin-bottom: 2rem;
    border-radius: var(--radius-md);
  }

  #hero {
    padding: 2rem 1.25rem;
  }

  #hero > p:last-child {
    flex-direction: column;
    align-items: stretch;
  }

  #hero > p:last-child a {
    text-align: center;
  }

  #articles {
    grid-template-columns: 1fr;
  }

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

  #faq summary {
    padding: 1rem 1.15rem;
    font-size: 0.92rem;
  }

  #faq details p {
    padding: 0 1.15rem 1rem;
    font-size: 0.88rem;
  }

  #contact address {
    padding: 1.25rem;
  }

  #back-to-top {
    right: 1rem;
    bottom: 1rem;
    width: 44px;
    height: 44px;
    font-size: 0.65rem;
  }

  footer {
    padding: 2rem 1rem 1.5rem;
  }
}

/* ===== Responsive: Small Mobile ===== */
@media (max-width: 480px) {
  body {
    font-size: 15px;
  }

  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }
  h3 { font-size: 1.05rem; }

  main > section {
    padding: 1.25rem 1rem;
  }

  #hero {
    padding: 1.75rem 1rem;
  }

  #howto ol li {
    padding: 0.8rem 0.9rem 0.8rem 2.9rem;
    font-size: 0.9rem;
  }

  #howto ol li::before {
    left: 0.75rem;
    width: 1.5rem;
    height: 1.5rem;
    font-size: 0.75rem;
  }

  #sitemap ul li a,
  #links ul li a {
    font-size: 0.82rem;
    padding: 0.4rem 0.85rem;
  }
}

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

  main > section {
    opacity: 1;
    transform: none;
  }
}

/* ===== Print ===== */
@media print {
  #site-header,
  #back-to-top,
  footer {
    display: none;
  }

  main > section {
    break-inside: avoid;
    box-shadow: none;
    border: 1px solid #ccc;
    opacity: 1;
    transform: none;
  }

  body {
    background: #fff;
    color: #000;
  }
}