/* ========== CSS Variables ========== */
:root {
  --brand-blue: #229ED9;
  --brand-deep: #1A8BC5;
  --brand-light: #E7F5FC;
  --surface-dark: #0A1628;
  --surface-card: #111E33;
  --text-primary: #17212B;
  --text-light: #F8F9FA;
  --text-muted: #8A9BA8;
  --border-color: rgba(34, 158, 217, 0.15);
  --success: #34C759;
  --bg-section: #F5F8FA;
  --container-max: 1200px;
  --section-gap: 100px;
  --card-gap: 24px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text-primary);
  line-height: 1.7;
  background: #fff;
  overflow-x: hidden;
}

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

a {
  color: var(--brand-blue);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--brand-deep);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  outline: none;
}

/* ========== Particle Background ========== */
.particle-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* ========== Layout ========== */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

.section {
  padding: var(--section-gap) 0;
  position: relative;
  z-index: 1;
}

.section-dark {
  background: linear-gradient(135deg, var(--surface-dark) 0%, #172D4D 100%);
}

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

.section-white {
  background: #fff;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--card-gap);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--card-gap);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--card-gap);
}

/* ========== Typography ========== */
.display {
  font-size: 56px;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h1, .h1 {
  font-size: 42px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

h2, .h2 {
  font-size: 32px;
  font-weight: 700;
  line-height: 1.3;
}

h3, .h3 {
  font-size: 24px;
  font-weight: 600;
  line-height: 1.4;
}

.body-large {
  font-size: 18px;
  line-height: 1.6;
  letter-spacing: 0.01em;
}

.body {
  font-size: 16px;
  line-height: 1.7;
  letter-spacing: 0.01em;
}

.small {
  font-size: 14px;
  line-height: 1.5;
  letter-spacing: 0.02em;
}

.caption {
  font-size: 12px;
  font-weight: 500;
  line-height: 1.4;
  letter-spacing: 0.03em;
}

.text-light {
  color: var(--text-light);
}

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

.text-brand {
  color: var(--brand-blue);
}

.text-success {
  color: var(--success);
}

.text-center {
  text-align: center;
}

/* ========== Navbar ========== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 64px;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  z-index: 1000;
  transition: box-shadow 0.3s ease;
}

.navbar.scrolled {
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
}

.navbar-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
}

.nav-logo svg {
  width: 32px;
  height: 32px;
}

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

.nav-links a {
  font-size: 15px;
  font-weight: 500;
  color: var(--text-primary);
  padding: 8px 0;
  position: relative;
  transition: color 0.2s ease;
}

.nav-links a:hover {
  color: var(--brand-blue);
}

.nav-links a.active {
  color: var(--brand-blue);
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--brand-blue);
  border-radius: 1px;
}

.nav-toggle {
  display: none;
  width: 28px;
  height: 28px;
  background: none;
  padding: 0;
}

/* ========== Glass Cards ========== */
.glass-card {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 32px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
  transition: all 0.3s ease;
}

.glass-card:hover {
  border-color: rgba(34, 158, 217, 0.25);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
}

.glass-card-dark {
  background: rgba(17, 30, 51, 0.85);
  backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 32px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
  color: var(--text-light);
}

.glass-card-dark:hover {
  border-color: rgba(34, 158, 217, 0.3);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

/* ========== Buttons ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.btn-primary {
  background: var(--brand-blue);
  color: #fff;
}

.btn-primary:hover {
  background: var(--brand-deep);
  color: #fff;
}

.btn-primary:active {
  transform: scale(0.97);
}

.btn-secondary {
  background: transparent;
  color: var(--brand-blue);
  border: 1px solid var(--brand-blue);
}

.btn-secondary:hover {
  background: var(--brand-light);
  color: var(--brand-deep);
}

.btn-large {
  padding: 18px 48px;
  font-size: 18px;
}

/* ========== Hero ========== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, var(--surface-dark) 0%, var(--surface-card) 50%, #172D4D 100%);
}

.hero-bg-img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.3;
  z-index: 0;
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 1;
  padding: 120px 24px 80px;
}

.hero-logo {
  width: 120px;
  height: 120px;
  margin: 0 auto 32px;
  opacity: 0;
  transform: scale(0.8);
  transition: all 1.5s ease-out;
}

.hero-logo.show {
  opacity: 1;
  transform: scale(1);
}

.hero-logo svg {
  width: 100%;
  height: 100%;
}

.hero-title {
  color: var(--text-light);
  margin-bottom: 16px;
}

.hero-subtitle {
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 40px;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* Scroll indicator */
.scroll-indicator {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  animation: bounce 2s infinite;
}

.scroll-indicator svg {
  width: 24px;
  height: 24px;
  color: var(--text-muted);
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
  40% { transform: translateX(-50%) translateY(-10px); }
  60% { transform: translateX(-50%) translateY(-5px); }
}

/* ========== Feature Cards ========== */
.feature-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 20px;
  color: var(--brand-blue);
}

.feature-title {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.feature-desc {
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.7;
}

/* ========== Platform Cards ========== */
.platform-card {
  text-align: center;
  padding: 40px 24px;
}

.platform-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 20px;
  color: var(--text-muted);
  transition: color 0.3s ease;
}

.platform-card:hover .platform-icon {
  color: var(--brand-blue);
}

.platform-name {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 8px;
}

.platform-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 20px;
}

/* ========== Feature Detail ========== */
.feature-detail {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.feature-detail.reverse {
  direction: rtl;
}

.feature-detail.reverse > * {
  direction: ltr;
}

.feature-detail-img {
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

.feature-detail-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.feature-detail-text h3 {
  margin-bottom: 16px;
}

.feature-detail-text p {
  color: var(--text-muted);
  margin-bottom: 12px;
}

/* ========== Reviews ========== */
.review-card {
  padding: 28px;
}

.review-stars {
  display: flex;
  gap: 4px;
  margin-bottom: 16px;
}

.review-stars svg {
  width: 18px;
  height: 18px;
}

.review-user {
  font-weight: 600;
  margin-bottom: 8px;
  font-size: 15px;
}

.review-text {
  font-size: 14px;
  line-height: 1.7;
  color: var(--text-muted);
}

/* ========== Stats ========== */
.stat-number {
  font-size: 48px;
  font-weight: 800;
  color: var(--brand-blue);
  line-height: 1.1;
  margin-bottom: 8px;
}

.stat-label {
  font-size: 15px;
  color: var(--text-muted);
}

.stat-card {
  text-align: center;
  padding: 40px 24px;
}

/* ========== Comparison Table ========== */
.compare-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 24px;
}

.compare-table th,
.compare-table td {
  padding: 16px 20px;
  text-align: left;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.compare-table th {
  font-weight: 600;
  font-size: 15px;
  background: var(--brand-light);
  color: var(--text-primary);
}

.compare-table td:first-child {
  font-weight: 500;
}

.compare-table td:nth-child(2) {
  color: var(--brand-blue);
  font-weight: 500;
}

.compare-table tr:hover td {
  background: rgba(34, 158, 217, 0.04);
}

/* ========== Accordion ========== */
.accordion-item {
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.accordion-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 0;
  cursor: pointer;
  font-weight: 600;
  font-size: 17px;
  transition: color 0.2s ease;
  background: none;
  width: 100%;
  text-align: left;
}

.accordion-header:hover {
  color: var(--brand-blue);
}

.accordion-header svg {
  width: 20px;
  height: 20px;
  transition: transform 0.3s ease;
  flex-shrink: 0;
  margin-left: 12px;
}

.accordion-item.open .accordion-header svg {
  transform: rotate(180deg);
}

.accordion-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
}

.accordion-item.open .accordion-body {
  max-height: 500px;
  padding-bottom: 20px;
}

.accordion-body p {
  color: var(--text-muted);
  line-height: 1.8;
  font-size: 15px;
}

/* ========== Steps ========== */
.step-item {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  padding: 24px 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.step-number {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--brand-blue);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  font-weight: 700;
  flex-shrink: 0;
}

.step-content h4 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 6px;
}

.step-content p {
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.7;
}

/* ========== Timeline ========== */
.timeline {
  position: relative;
  padding-left: 32px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border-color);
}

.timeline-item {
  position: relative;
  padding-bottom: 28px;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -28px;
  top: 4px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--brand-blue);
  border: 2px solid #fff;
  box-shadow: 0 0 0 2px var(--brand-blue);
}

.timeline-version {
  font-weight: 700;
  font-size: 16px;
  color: var(--brand-blue);
  margin-bottom: 4px;
}

.timeline-date {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.timeline-desc {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ========== Reveal Animation ========== */
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: all 0.6s ease-out;
}

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

/* ========== Footer ========== */
.footer {
  background: var(--surface-dark);
  border-top: 1px solid var(--border-color);
  padding: 40px 24px;
  text-align: center;
  position: relative;
  z-index: 1;
}

.footer p {
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1.8;
}

.footer .safe-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--success);
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 12px;
}

.footer .safe-badge svg {
  width: 16px;
  height: 16px;
}

/* ========== SEO Page Specific ========== */
.seo-article {
  max-width: 800px;
  margin: 0 auto;
}

.seo-article h3 {
  margin: 32px 0 16px;
}

.seo-article p {
  margin-bottom: 16px;
  color: var(--text-muted);
  line-height: 1.8;
}

.tip-card {
  padding: 24px;
}

.tip-card h4 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

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

/* ========== Download Page Specific ========== */
.download-hero-card {
  max-width: 560px;
  margin: 0 auto;
  text-align: center;
  padding: 48px 40px;
}

.download-hero-card .platform-icon {
  width: 80px;
  height: 80px;
  color: var(--brand-blue);
}

.version-info {
  display: flex;
  gap: 24px;
  justify-content: center;
  margin: 20px 0;
  flex-wrap: wrap;
}

.version-info-item {
  text-align: center;
}

.version-info-item .label {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.version-info-item .value {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
}

.platform-download-card {
  padding: 32px;
}

.platform-download-card .platform-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
}

.platform-download-card .platform-header svg {
  width: 48px;
  height: 48px;
  color: var(--brand-blue);
}

.platform-meta {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 20px;
}

.platform-meta-item {
  font-size: 14px;
}

.platform-meta-item .meta-label {
  color: var(--text-muted);
  font-size: 12px;
  margin-bottom: 2px;
}

/* ========== Keywords Section ========== */
.keywords-section {
  background: var(--bg-section);
  padding: 60px 0;
}

.keywords-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-top: 24px;
}

.keyword-tag {
  display: inline-flex;
  align-items: center;
  padding: 8px 20px;
  border-radius: 100px;
  background: #fff;
  border: 1px solid var(--border-color);
  font-size: 14px;
  color: var(--text-primary);
  font-weight: 500;
}

/* ========== CTA Section ========== */
.cta-section {
  padding: 80px 0;
  text-align: center;
}

.cta-section h2 {
  margin-bottom: 24px;
}

/* ========== Animations ========== */
@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

@keyframes countUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ========== Responsive ========== */
@media (max-width: 1200px) {
  .display { font-size: 48px; }
  .h1 { font-size: 36px; }
}

@media (max-width: 768px) {
  .display { font-size: 36px; }
  .h1 { font-size: 28px; }
  .h2 { font-size: 24px; }
  .h3 { font-size: 20px; }

  .section {
    padding: 60px 0;
  }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .feature-detail {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .feature-detail.reverse {
    direction: ltr;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 16px 24px;
    gap: 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  }

  .nav-links.active {
    display: flex;
  }

  .nav-links a {
    padding: 12px 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    width: 100%;
  }

  .nav-links a.active::after {
    display: none;
  }

  .nav-links a.active {
    background: var(--brand-light);
    margin: 0 -24px;
    padding: 12px 24px;
  }

  .nav-toggle {
    display: block;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .hero-buttons .btn {
    width: 100%;
    max-width: 280px;
  }

  .compare-table {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
  }

  .compare-table th,
  .compare-table td {
    padding: 12px 16px;
    font-size: 14px;
  }

  .step-item {
    gap: 16px;
  }

  .platform-meta {
    grid-template-columns: 1fr;
  }

  .version-info {
    gap: 16px;
  }
}

@media (max-width: 480px) {
  .display { font-size: 28px; }
  .h1 { font-size: 24px; }
  .h2 { font-size: 20px; }

  .glass-card,
  .glass-card-dark {
    padding: 20px;
  }

  .container {
    padding: 0 16px;
  }

  .btn {
    padding: 12px 24px;
    font-size: 15px;
  }

  .btn-large {
    padding: 16px 32px;
    font-size: 16px;
  }
}