/* ========== 设计系统：陕西锦言沛泽科技 ========== */
:root {
  /* 色彩 */
  --color-deep: #0F172A;
  --color-deep-rgb: 15, 23, 42;
  --color-silver: #E2E8F0;
  --color-cyan: #06B6D4;
  --color-cyan-rgb: 6, 182, 212;
  --color-white: #FFFFFF;
  --color-bg-sub: rgba(226, 232, 240, 0.06);
  --color-border: rgba(226, 232, 240, 0.2);

  /* 字体 */
  --font-sans: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
  --fw-normal: 400;
  --fw-medium: 600;
  --fw-bold: 700;
  --lh-tight: 1.2;
  --lh-body: 1.5;

  /* 字号 PC */
  --text-hero: 48px;
  --text-section: 36px;
  --text-subsection: 28px;
  --text-card: 24px;
  --text-body: 16px;
  --text-small: 14px;
  --text-hero-sub: 20px;

  /* 间距与布局 */
  --header-height: 80px;
  --header-height-scrolled: 70px;
  --container-max: 1200px;
  --section-gap: 100px;
  --card-gap: 30px;
  --radius: 8px;
  --radius-card: 12px;

  /* 动效 */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --duration: 0.35s;
  --duration-slow: 0.5s;
}

/* 重置与基础 */
*, *::before, *::after { box-sizing: border-box; }
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: var(--fw-normal);
  font-size: var(--text-body);
  line-height: var(--lh-body);
  color: var(--color-silver);
  background: var(--color-deep);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
img { max-width: 100%; height: auto; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

/* 焦点可见性（无障碍） */
:focus-visible {
  outline: 2px solid var(--color-cyan);
  outline-offset: 2px;
}

/* ========== 板块1：顶部导航栏 ========== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(var(--color-deep-rgb), 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: height var(--duration) var(--ease),
              background var(--duration) var(--ease);
}
.header.scrolled {
  height: var(--header-height-scrolled);
  background: var(--color-deep);
}
.header-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--color-silver);
  transition: color var(--duration) var(--ease),
              filter var(--duration) var(--ease);
}
.logo:hover { color: var(--color-white); filter: brightness(1.1); }
.logo-icon {
  width: 72px;
  height: 72px;
  display: inline-flex;
  align-items: center;
  color: var(--color-cyan);
  flex: 0 0 auto;
}
.logo-icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: center;
}
.header.scrolled .logo-icon { width: 60px; height: 60px; }
.logo-text {
  font-size: 18px;
  font-weight: var(--fw-bold);
  color: var(--color-white);
  line-height: 1.2;
  white-space: nowrap;
}
.header.scrolled .logo-text {
  font-size: 16px;
}

.nav { display: none; }
@media (min-width: 1024px) {
  .nav { display: block; }
  .nav-list {
    display: flex;
    align-items: center;
    gap: 32px;
  }
  .nav-list a {
    position: relative;
    font-size: 15px;
    font-weight: var(--fw-medium);
    color: var(--color-silver);
    padding: 4px 0;
    transition: color var(--duration) var(--ease),
                transform var(--duration) var(--ease);
  }
  .nav-list a::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 0;
    height: 1px;
    background: linear-gradient(90deg, var(--color-cyan), transparent);
    transition: width var(--duration) var(--ease);
  }
  .nav-list a:hover {
    color: var(--color-cyan);
    transform: translateY(-2px);
  }
  .nav-list a:hover::after { width: 100%; }
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-weight: var(--fw-medium);
  font-size: 14px;
  transition: background var(--duration) var(--ease),
              color var(--duration) var(--ease),
              transform var(--duration) var(--ease);
}
.btn-outline {
  color: var(--color-cyan);
  border: 1px solid var(--color-cyan);
}
.btn-outline:hover {
  background: var(--color-cyan);
  color: var(--color-white);
}
.btn-primary {
  background: var(--color-cyan);
  color: var(--color-white);
  border: 1px solid var(--color-cyan);
}
.btn-primary:hover {
  filter: brightness(1.1);
  transform: scale(1.02);
}
.btn-ghost {
  color: var(--color-cyan);
  border: 1px solid var(--color-cyan);
  background: transparent;
}
.btn-ghost:hover { background: rgba(var(--color-cyan-rgb), 0.2); }

.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 32px;
  height: 32px;
  padding: 4px;
  color: var(--color-silver);
}
.hamburger span {
  display: block;
  width: 100%;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  transition: transform var(--duration) var(--ease),
              opacity var(--duration) var(--ease);
}
.hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}
.hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}
@media (min-width: 1024px) {
  .hamburger { display: none; }
  .btn-outline { display: inline-flex; }
}

@media (max-width: 767px) {
  .logo-icon {
    width: 48px;
    height: 48px;
  }
  .header.scrolled .logo-icon {
    width: 42px;
    height: 42px;
  }
  .logo-text {
    font-size: 12px;
    max-width: 150px;
    white-space: normal;
  }
  .header.scrolled .logo-text {
    font-size: 11px;
  }
}

/* 移动端侧边导航 */
.mobile-nav {
  position: fixed;
  top: 0;
  right: -100%;
  width: 280px;
  max-width: 85vw;
  height: 100vh;
  background: var(--color-deep);
  z-index: 999;
  padding: calc(var(--header-height) + 24px) 24px 24px;
  transition: right var(--duration-slow) var(--ease);
  overflow-y: auto;
}
.mobile-nav.is-open { right: 0; }
.mobile-nav-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.mobile-nav-list a {
  display: block;
  padding: 12px 0;
  font-weight: var(--fw-medium);
  color: var(--color-silver);
  border-bottom: 1px solid var(--color-border);
  transition: color var(--duration) var(--ease);
}
.mobile-nav-list a:hover { color: var(--color-cyan); }
@media (min-width: 1024px) { .mobile-nav { display: none; } }

/* ========== 板块2：首屏 Hero ========== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: var(--header-height) 24px 80px;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.hero-gradient {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg,
    var(--color-deep) 0%,
    rgba(15, 23, 42, 0.98) 50%,
    var(--color-deep) 100%);
}
.hero-lines {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(var(--color-cyan-rgb), 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(var(--color-cyan-rgb), 0.06) 1px, transparent 1px);
  background-size: 60px 60px;
  animation: lineFlow 20s linear infinite;
}
@keyframes lineFlow {
  0% { transform: translate(0, 0); }
  100% { transform: translate(60px, 60px); }
}
.hero-particles {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0.6;
}
.hero-glow {
  position: absolute;
  top: 0;
  left: -50%;
  width: 200%;
  height: 60%;
  background: linear-gradient(90deg,
    transparent,
    rgba(var(--color-cyan-rgb), 0.08),
    transparent);
  animation: glowMove 8s ease-in-out infinite;
}
@keyframes glowMove {
  0%, 100% { transform: translateX(0); }
  50% { transform: translateX(25%); }
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: var(--container-max);
  margin: 0 auto;
  width: 100%;
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 48px;
  align-items: center;
}
@media (max-width: 767px) {
  .hero-content { grid-template-columns: 1fr; grid-template-rows: auto auto; }
  .hero-text { order: 1; }
  .hero-visual { order: 2; }
}

.hero-text { opacity: 0; transform: translateX(-24px) scale(0.98); }
.hero.animate-in .hero-text {
  animation: heroTextIn 0.4s var(--ease) forwards;
}
@keyframes heroTextIn {
  to { opacity: 1; transform: translateX(0) scale(1); }
}
.hero-title {
  font-size: clamp(32px, 5vw, var(--text-hero));
  font-weight: var(--fw-bold);
  color: var(--color-white);
  line-height: var(--lh-tight);
  margin: 0 0 16px;
}
.hero-subtitle {
  font-size: clamp(16px, 2vw, var(--text-hero-sub));
  color: var(--color-silver);
  margin: 0 0 32px;
  max-width: 520px;
  line-height: 1.5;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}
.hero-actions .btn { padding: 12px 24px; font-size: 16px; }
.hero-actions .btn:active { transform: translateY(3px); }

.hero-visual {
  position: relative;
  min-height: 280px;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
}
.hero.animate-in .hero-visual {
  animation: heroVisualIn 0.6s var(--ease) 0.2s forwards;
}
@keyframes heroVisualIn {
  to { opacity: 1; }
}
.hero-visual-inner {
  position: relative;
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1;
}
.hero-3d-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  perspective: 800px;
}
.cube {
  width: 120px;
  height: 120px;
  position: relative;
  transform-style: preserve-3d;
  animation: cubeRotate 12s linear infinite;
}
.hero-visual:hover .cube { animation-play-state: paused; }
.cube .face {
  position: absolute;
  width: 120px;
  height: 120px;
  border: 1px solid rgba(var(--color-cyan-rgb), 0.4);
  background: rgba(var(--color-cyan-rgb), 0.08);
  backface-visibility: visible;
  display: flex;
  align-items: center;
  justify-content: center;
}
.cube .front  { transform: translateZ(60px); }
.cube .back   { transform: rotateY(180deg) translateZ(60px); }
.cube .right  { transform: rotateY(90deg) translateZ(60px); }
.cube .left   { transform: rotateY(-90deg) translateZ(60px); }
.cube .top    { transform: rotateX(90deg) translateZ(60px); }
.cube .bottom { transform: rotateX(-90deg) translateZ(60px); }
@keyframes cubeRotate {
  from { transform: rotateX(-12deg) rotateY(0deg); }
  to { transform: rotateX(-12deg) rotateY(360deg); }
}
.hero-particles-inline {
  position: absolute;
  inset: -20px;
  pointer-events: none;
}

/* 关于我们 */
.about { background: var(--color-deep); }
.about-intro {
  max-width: 720px;
  margin: 0 auto;
  font-size: var(--text-body);
  color: var(--color-silver);
  line-height: 1.6;
  text-align: center;
}

/* ========== 通用区块 ========== */
.section {
  padding: var(--section-gap) 24px;
  position: relative;
  scroll-margin-top: var(--header-height);
}
.container {
  max-width: var(--container-max);
  margin: 0 auto;
}
.section-title {
  font-size: clamp(28px, 4vw, var(--text-section));
  font-weight: var(--fw-bold);
  color: var(--color-white);
  text-align: center;
  margin: 0 0 48px;
  position: relative;
  display: inline-block;
  left: 50%;
  transform: translateX(-50%);
}
.section-title::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: -8px;
  transform: translateX(-50%);
  width: 33%;
  height: 1px;
  background: var(--color-cyan);
}

/* ========== 板块3：核心业务 ========== */
.business { background: var(--color-deep); }
.business-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--card-gap);
  align-items: stretch;
}
@media (max-width: 1199px) {
  .business-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 767px) {
  .business-grid { grid-template-columns: 1fr; }
}

.card {
  background: var(--color-bg-sub);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 32px;
  position: relative;
  overflow: hidden;
  transition: transform var(--duration) var(--ease),
              box-shadow var(--duration) var(--ease),
              border-color var(--duration) var(--ease);
}
.card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(135deg, var(--color-cyan), transparent 50%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0.5;
  pointer-events: none;
  transition: opacity var(--duration) var(--ease);
}
.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
  border-color: rgba(var(--color-cyan-rgb), 0.4);
}
.card:hover::before { opacity: 1; }
.card-icon {
  width: 40px;
  height: 40px;
  color: var(--color-cyan);
  margin-bottom: 20px;
  transition: transform var(--duration-slow) var(--ease);
}
.card:hover .card-icon { transform: rotate(360deg); }
.card-title {
  font-size: var(--text-card);
  font-weight: var(--fw-bold);
  color: var(--color-white);
  margin: 0 0 10px;
}
.card-desc {
  font-size: var(--text-body);
  color: var(--color-silver);
  margin: 0 0 16px;
  line-height: 1.5;
  min-height: 4em;
}
.card-link {
  color: var(--color-cyan);
  font-weight: var(--fw-medium);
  font-size: 14px;
  transition: opacity var(--duration) var(--ease);
}
.card-link:hover { text-decoration: underline; }
.card-tag {
  display: inline-block;
  margin-top: 12px;
  font-size: var(--text-small);
  color: var(--color-silver);
  opacity: 0.9;
}

/* 滚动渐显 */
.business-card {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}
.business-card.visible {
  opacity: 1;
  transform: translateY(0);
}
.business-card[data-index="1"].visible { transition-delay: 0.1s; }
.business-card[data-index="2"].visible { transition-delay: 0.2s; }

/* ========== 板块5：技术实力 ========== */
.tech { padding-top: 0; }
.tech-banner {
  background: linear-gradient(90deg, rgba(var(--color-cyan-rgb), 0.15), rgba(var(--color-cyan-rgb), 0.05));
  padding: 48px 24px;
  margin-bottom: 48px;
}
.tech-slogan {
  font-size: clamp(24px, 3vw, 32px);
  font-weight: var(--fw-bold);
  color: var(--color-white);
  text-align: center;
  margin: 0;
}
.tech-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}
@media (max-width: 767px) { .tech-grid { grid-template-columns: 1fr; } }
.tech-card {
  background: rgba(var(--color-deep-rgb), 0.6);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 28px;
  transition: border-color var(--duration) var(--ease),
              background var(--duration) var(--ease);
}
.tech-card:hover {
  border-color: var(--color-cyan);
  background: rgba(var(--color-deep-rgb), 0.8);
}
.tech-card-icon {
  width: 48px;
  height: 48px;
  color: var(--color-cyan);
  margin-bottom: 16px;
  transition: transform var(--duration) var(--ease);
}
.tech-card:hover .tech-card-icon { transform: translateY(-4px); }
.tech-card-title {
  font-size: var(--text-card);
  font-weight: var(--fw-bold);
  color: var(--color-white);
  margin: 0 0 8px;
}
.tech-card-desc {
  font-size: var(--text-body);
  color: var(--color-silver);
  margin: 0;
  line-height: 1.5;
}

.tech-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
@media (max-width: 767px) { .tech-stats { grid-template-columns: 1fr; } }
.stat-card {
  background: rgba(var(--color-cyan-rgb), 0.12);
  border-radius: var(--radius-card);
  padding: 32px;
  text-align: center;
}
.stat-number { font-size: 48px; font-weight: var(--fw-bold); color: var(--color-cyan); }
.stat-suffix { font-size: 32px; font-weight: var(--fw-bold); color: var(--color-cyan); }
.stat-label { display: block; font-size: var(--text-body); color: var(--color-white); margin-top: 8px; }

/* 技术卡片滚动显 */
.tech-card {
  opacity: 0;
  transform: translateX(-20px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease), border-color var(--duration), background var(--duration);
}
.tech-card.visible {
  opacity: 1;
  transform: translateX(0);
}
.tech-card[data-index="1"].visible { transition-delay: 0.1s; }
.tech-card[data-index="2"].visible { transition-delay: 0.2s; }
.tech-card[data-index="3"].visible { transition-delay: 0.3s; }
.stat-card {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}
.stat-card.visible {
  opacity: 1;
  transform: translateY(0);
}
.stat-card:nth-child(1).visible { transition-delay: 0.1s; }
.stat-card:nth-child(2).visible { transition-delay: 0.2s; }
.stat-card:nth-child(3).visible { transition-delay: 0.3s; }

/* ========== 板块6：合作伙伴与新闻 ========== */
.partners-news { background: var(--color-deep); }
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}
@media (max-width: 767px) { .two-col { grid-template-columns: 1fr; } }
.subsection-title {
  font-size: var(--text-subsection);
  font-weight: var(--fw-bold);
  color: var(--color-white);
  margin: 0 0 24px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-cyan);
  display: inline-block;
}
.partners-col { background: var(--color-deep); }
.partners-logos {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-bottom: 24px;
}
@media (max-width: 767px) { .partners-logos { grid-template-columns: repeat(2, 1fr); } }
.partner-logo {
  aspect-ratio: 2/1;
  background: rgba(255, 255, 255, 0.98);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  overflow: hidden;
  filter: grayscale(1);
  transition: filter var(--duration) var(--ease),
              transform var(--duration) var(--ease),
              border-color var(--duration) var(--ease),
              box-shadow var(--duration) var(--ease);
}
.partner-logo:hover, .partner-logo:focus {
  filter: grayscale(0);
  transform: scale(1.05);
  border-color: rgba(var(--color-cyan-rgb), 0.45);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.18);
}
.partner-logo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  display: block;
  opacity: 0.96;
  transform: scale(1.08);
  transition: opacity var(--duration) var(--ease), transform var(--duration) var(--ease);
}
.partner-logo:hover img,
.partner-logo:focus img {
  opacity: 1;
  transform: scale(1.12);
}
.link-cyan {
  color: var(--color-cyan);
  font-weight: var(--fw-medium);
  transition: opacity var(--duration) var(--ease);
}
.link-cyan:hover { text-decoration: underline; }

.news-col { background: var(--color-bg-sub); padding: 24px; border-radius: var(--radius-card); }
.news-list { display: flex; flex-direction: column; gap: 20px; }
.news-card {
  padding: 20px;
  background: rgba(var(--color-deep-rgb), 0.4);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  transition: transform var(--duration) var(--ease),
              box-shadow var(--duration) var(--ease);
}
.news-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2);
}
.news-time { font-size: 14px; color: var(--color-silver); display: block; margin-bottom: 6px; }
.news-title { margin: 0 0 8px; font-size: 18px; font-weight: var(--fw-bold); }
.news-title a {
  color: var(--color-white);
  transition: color var(--duration) var(--ease);
}
.news-title a:hover { color: var(--color-cyan); }
.news-excerpt { font-size: var(--text-body); color: var(--color-silver); margin: 0 0 12px; line-height: 1.4; }

/* ========== 板块7：底部 ========== */
.footer {
  background: var(--color-deep);
  padding: 48px 24px 24px;
}
.footer-line {
  height: 1px;
  background: var(--color-border);
  margin-bottom: 48px;
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  margin-bottom: 40px;
}
@media (max-width: 1199px) { .footer-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 767px) { .footer-grid { grid-template-columns: 1fr; } }
.footer-heading {
  font-size: 16px;
  font-weight: var(--fw-bold);
  color: var(--color-white);
  margin: 0 0 16px;
}
.footer-text {
  font-size: var(--text-body);
  color: var(--color-silver);
  margin: 0;
  line-height: 1.6;
}
.footer-link {
  color: var(--color-cyan);
  transition: opacity var(--duration) var(--ease);
}
.footer-link:hover { opacity: 0.9; text-decoration: underline; }
.footer-nav {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-nav a {
  color: var(--color-silver);
  transition: color var(--duration) var(--ease);
}
.footer-nav a:hover { color: var(--color-cyan); text-decoration: underline; }
.footer-social {
  display: flex;
  gap: 16px;
  align-items: center;
  flex-wrap: wrap;
}
.footer-social-item {
  position: relative;
}
.footer-social-link {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-cyan);
  border: 1px solid var(--color-cyan);
  border-radius: var(--radius);
  background: rgba(var(--color-cyan-rgb), 0.08);
  font-size: 12px;
  transition: transform var(--duration) var(--ease),
              background var(--duration) var(--ease);
}
.footer-social-link:hover {
  transform: scale(1.2);
  background: rgba(var(--color-cyan-rgb), 0.2);
}
.footer-social-icon {
  font-size: 18px;
  font-weight: var(--fw-bold);
  line-height: 1;
}
.footer-qr-popover {
  position: absolute;
  left: 50%;
  bottom: calc(100% + 14px);
  transform: translateX(-50%) translateY(8px);
  width: 220px;
  padding: 10px;
  border-radius: 14px;
  background: #ffffff;
  border: 1px solid rgba(var(--color-cyan-rgb), 0.24);
  box-shadow: 0 18px 40px rgba(0, 0, 0, 0.28);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity var(--duration) var(--ease),
              transform var(--duration) var(--ease),
              visibility var(--duration) var(--ease);
  z-index: 10;
}
.footer-qr-popover img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
}
.footer-social-item-wechat:hover .footer-qr-popover,
.footer-social-item-wechat:focus-within .footer-qr-popover {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}
@media (max-width: 767px) {
  .footer-qr-popover {
    left: 0;
    transform: translateX(0) translateY(8px);
    width: 180px;
  }
  .footer-social-item-wechat:hover .footer-qr-popover,
  .footer-social-item-wechat:focus-within .footer-qr-popover {
    transform: translateX(0) translateY(0);
  }
}
.footer-bottom {
  text-align: center;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}
.footer-copy {
  font-size: var(--text-small);
  color: var(--color-silver);
  margin: 0 0 8px;
}
.footer-a11y {
  font-size: var(--text-small);
  color: var(--color-cyan);
  transition: opacity var(--duration) var(--ease);
}
.footer-a11y:hover { opacity: 0.9; }

#hero { scroll-margin-top: 0; }
body.a11y-mode {
  --text-body: 18px;
  --text-small: 16px;
}
body.a11y-mode .section-title,
body.a11y-mode .card-title,
body.a11y-mode .footer-heading {
  letter-spacing: 0.02em;
}