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

:root {
  --primary: #0066ff;
  --primary-dark: #0052cc;
  --primary-light: #e8f1ff;
  --accent: #00c2ff;
  --text: #1a1a2e;
  --text-muted: #5a6278;
  --bg: #ffffff;
  --bg-alt: #f5f8ff;
  --border: #e2e8f0;
  --shadow: 0 4px 24px rgba(0, 102, 255, 0.12);
  --radius: 12px;
  --header-h: 72px;
}

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--primary-dark); }

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Header ===== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  height: var(--header-h);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-h);
}

.logo img { height: 40px; width: auto; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  color: var(--text);
  font-size: 15px;
  font-weight: 500;
}

.nav-links a:hover,
.nav-links a.active { color: var(--primary); }

/* ===== Download Button ===== */
.btn-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 36px;
  font-size: 17px;
  font-weight: 700;
  color: #fff;
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  border: none;
  border-radius: 50px;
  cursor: pointer;
  box-shadow: 0 6px 24px rgba(0, 102, 255, 0.45);
  transition: transform 0.2s, box-shadow 0.2s;
  position: relative;
  overflow: hidden;
  text-decoration: none;
  letter-spacing: 0.5px;
}

.btn-download::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.25) 0%, transparent 60%);
  pointer-events: none;
}

.btn-download:hover {
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 10px 32px rgba(0, 102, 255, 0.55);
  color: #fff;
}

.btn-download:active { transform: translateY(0) scale(0.98); }

.btn-download-lg {
  padding: 18px 48px;
  font-size: 20px;
}

.btn-download .icon {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

.btn-download-pulse {
  animation: pulse-glow 2s ease-in-out infinite;
}

@keyframes pulse-glow {
  0%, 100% { box-shadow: 0 6px 24px rgba(0, 102, 255, 0.45); }
  50% { box-shadow: 0 6px 40px rgba(0, 194, 255, 0.7), 0 0 0 8px rgba(0, 102, 255, 0.1); }
}

.btn-download-header {
  padding: 10px 24px;
  font-size: 14px;
}

/* ===== Hero ===== */
.hero {
  padding: 24px 0 80px;
  background: linear-gradient(160deg, var(--bg-alt) 0%, #fff 50%, var(--primary-light) 100%);
  overflow: hidden;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.hero-content h1 {
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 20px;
  color: var(--text);
}

.hero-content h1 span {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 17px;
  color: var(--text-muted);
  margin-bottom: 32px;
  max-width: 520px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
}

.hero-actions .sub-link {
  font-size: 15px;
  color: var(--text-muted);
}

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

/* ===== Sections ===== */
.section {
  padding: 80px 0;
}

.section-alt { background: var(--bg-alt); }

.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-header h2 {
  font-size: clamp(24px, 3vw, 36px);
  font-weight: 700;
  margin-bottom: 12px;
}

.section-header p {
  color: var(--text-muted);
  font-size: 16px;
  max-width: 640px;
  margin: 0 auto;
}

/* ===== Features Grid ===== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.feature-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 24px;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
}

.feature-card img {
  width: 100%;
  max-height: 180px;
  object-fit: contain;
  margin: 0 auto 20px;
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 10px;
}

.feature-card p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ===== About / Intro ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.about-grid.reverse { direction: rtl; }
.about-grid.reverse > * { direction: ltr; }

.about-text h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 16px;
}

.about-text p {
  color: var(--text-muted);
  margin-bottom: 12px;
  font-size: 15px;
}

.about-image img {
  border-radius: var(--radius);
}

/* ===== Use Cases ===== */
.use-cases {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.use-case {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 28px;
  border: 1px solid var(--border);
}

.use-case h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--primary);
}

.use-case p {
  font-size: 14px;
  color: var(--text-muted);
}

/* ===== CTA Banner ===== */
.cta-banner {
  background: linear-gradient(135deg, var(--primary) 0%, #0044bb 100%);
  border-radius: 20px;
  padding: 56px 48px;
  text-align: center;
  color: #fff;
  margin: 0 24px;
  max-width: 1152px;
  margin-left: auto;
  margin-right: auto;
}

.cta-banner h2 {
  font-size: clamp(22px, 3vw, 32px);
  font-weight: 700;
  margin-bottom: 12px;
}

.cta-banner p {
  font-size: 16px;
  opacity: 0.9;
  margin-bottom: 28px;
}

.cta-banner .btn-download {
  background: #fff;
  color: var(--primary);
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.2);
}

.cta-banner .btn-download:hover {
  background: var(--primary-light);
  color: var(--primary-dark);
}

/* ===== Download Page ===== */
.download-hero {
  padding: 24px 0 60px;
  background: linear-gradient(160deg, var(--bg-alt) 0%, var(--primary-light) 100%);
  text-align: center;
}

.download-hero h1 {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 800;
  margin-bottom: 16px;
}

.download-hero p {
  color: var(--text-muted);
  font-size: 17px;
  max-width: 600px;
  margin: 0 auto 36px;
}

.download-main-btn-wrap {
  margin-bottom: 48px;
}

/* ===== Platform Logos ===== */
.platform-section-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 20px;
  text-align: center;
}

.platform-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
  max-width: 720px;
  margin: 0 auto;
}

.platform-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 28px;
  min-width: 110px;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
  cursor: default;
}

.platform-item:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--primary);
}

.platform-item img {
  width: 48px;
  height: 48px;
  object-fit: contain;
}

.platform-item span {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
}

.platform-item a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  color: inherit;
  text-decoration: none;
}

.platform-item--dark img {
  background: #f0f4ff;
  border-radius: 8px;
  padding: 6px;
}

.platform-grid--hero {
  justify-content: flex-start;
}

.platform-grid--hero .platform-item {
  padding: 14px 20px;
  min-width: 90px;
}

.platform-grid--hero .platform-item img {
  width: 40px;
  height: 40px;
}

.platform-section-title--left {
  text-align: left;
  margin-top: 28px;
  margin-bottom: 16px;
}

.download-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 24px;
  margin-top: 32px;
}

.download-meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--text-muted);
}

.download-meta-item strong {
  color: var(--text);
  font-weight: 600;
}

.download-steps {
  max-width: 700px;
  margin: 0 auto;
}

.download-steps ol {
  padding-left: 20px;
}

.download-steps li {
  margin-bottom: 12px;
  color: var(--text-muted);
  font-size: 15px;
}

.download-steps li strong { color: var(--text); }

.download-faq { max-width: 800px; margin: 0 auto; }

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin-bottom: 12px;
  background: var(--bg);
}

.faq-item h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.faq-item p {
  font-size: 14px;
  color: var(--text-muted);
}

/* ===== Footer ===== */
.site-footer {
  background: #333;
  color: rgba(255, 255, 255, 0.7);
  padding: 48px 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-brand img { height: 36px; margin-bottom: 12px;  }

.footer-brand p {
  font-size: 14px;
  line-height: 1.7;
}

.footer-col h4 {
  color: #fff;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 16px;
}

.footer-col ul { list-style: none; }

.footer-col li { margin-bottom: 8px; }

.footer-col a {
  color: rgba(255, 255, 255, 0.65);
  font-size: 14px;
}

.footer-col a:hover { color: #fff; }

.footer-friends {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: 24px 0;
  margin-bottom: 8px;
}

.footer-friends h4 {
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 12px;
}

.footer-friends ul {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  list-style: none;
}

.footer-friends a {
  color: rgba(255, 255, 255, 0.55);
  font-size: 13px;
  transition: color 0.2s;
}

.footer-friends a:hover { color: #fff; }

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 20px;
  text-align: center;
  font-size: 13px;
}

/* ===== Breadcrumb ===== */
.breadcrumb {
  padding-top: calc(var(--header-h) + 12px);
  padding-bottom: 0;
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  list-style: none;
  font-size: 13px;
  color: var(--text-muted);
}

.breadcrumb li + li::before {
  content: "/";
  margin-right: 6px;
  color: var(--border);
}

.breadcrumb a {
  color: var(--text-muted);
}

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

.breadcrumb li:last-child span,
.breadcrumb li:last-child a {
  color: var(--text);
  font-weight: 500;
}

/* ===== SEO hidden but accessible ===== */
.seo-keywords {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .hero-inner,
  .about-grid,
  .features-grid,
  .use-cases,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .about-grid.reverse { direction: ltr; }

  .hero-image { order: -1; }

  .nav-links { gap: 16px; }
  .nav-links li:not(:last-child) { display: none; }
}