/* ========== CSS Variables ========== */
:root {
  --color-primary: #151c2e;
  --color-secondary: #171e31;
  --color-accent: #d0c7cc;
  --color-highlight: #0f82ce;
  --color-muted: #679ebd;
  --color-bg: #0e1321;
  --color-card: #1a2238;
  --color-card-hover: #1f2a45;
  --color-text: #e0dde0;
  --color-text-muted: #9a96a0;
  --color-border: rgba(103, 158, 189, 0.15);
  --color-glow: rgba(15, 130, 206, 0.25);
  --gradient-hero: linear-gradient(135deg, #0e1321 0%, #151c2e 50%, #1a2545 100%);
  --gradient-cta: linear-gradient(135deg, #0f82ce 0%, #0a6db3 50%, #085fa0 100%);
  --gradient-card: linear-gradient(145deg, rgba(26, 34, 56, 0.8), rgba(23, 30, 49, 0.6));
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 30px rgba(15, 130, 206, 0.15);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --font-body: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', sans-serif;
  --font-heading: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', sans-serif;
  --transition-fast: 0.2s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
}

html[lang="zh-TW"] {
  --font-body: 'Inter', 'Noto Sans TC', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', sans-serif;
  --font-heading: 'Inter', 'Noto Sans TC', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', sans-serif;
}

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

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

body {
  font-family: var(--font-body);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-highlight);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-muted);
}

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

ul, ol {
  list-style: none;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
  color: #ffffff;
}

/* ========== Utility Classes ========== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section-title {
  text-align: center;
  font-size: 2.25rem;
  margin-bottom: 16px;
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto 60px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  border: none;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-cta);
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(15, 130, 206, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(15, 130, 206, 0.45);
  color: #ffffff;
}

.btn-secondary {
  background: transparent;
  color: var(--color-highlight);
  border: 2px solid var(--color-highlight);
}

.btn-secondary:hover {
  background: rgba(15, 130, 206, 0.1);
  transform: translateY(-2px);
  color: var(--color-highlight);
}

.btn-large {
  padding: 18px 44px;
  font-size: 1.15rem;
  border-radius: var(--radius-md);
}

/* ========== Header / Navigation ========== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 16px 0;
  transition: all var(--transition-base);
}

.header.scrolled {
  background: rgba(14, 19, 33, 0.95);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: 10px 0;
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.header-logo img {
  width: 32px;
  height: 32px;
  border-radius: 6px;
}

.header-logo span {
  font-size: 1.3rem;
  font-weight: 700;
  color: #ffffff;
}

.nav {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  color: var(--color-text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.nav-link:hover {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.05);
}

.nav-link i {
  font-size: 0.85rem;
}

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

/* Language Switcher */
.lang-switcher {
  position: relative;
}

.lang-switcher-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.lang-switcher-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
}

.lang-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 180px;
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: all var(--transition-base);
  overflow: hidden;
  z-index: 100;
}

.lang-switcher.active .lang-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.lang-dropdown a {
  display: block;
  padding: 10px 18px;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}

.lang-dropdown a:hover,
.lang-dropdown a.active {
  background: rgba(15, 130, 206, 0.1);
  color: var(--color-highlight);
}

/* Mobile Menu */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  border: none;
  background: none;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition-base);
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ========== Hero Section ========== */
.hero {
  padding: 140px 0 80px;
  background: var(--gradient-hero);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(15, 130, 206, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(103, 158, 189, 0.06) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero .container {
  position: relative;
  z-index: 1;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 20px;
  background: rgba(15, 130, 206, 0.1);
  border: 1px solid rgba(15, 130, 206, 0.25);
  border-radius: 50px;
  color: var(--color-highlight);
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 28px;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #ffffff 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto 40px;
  line-height: 1.8;
}

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

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  margin-top: 60px;
  padding-top: 40px;
  border-top: 1px solid var(--color-border);
}

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

.hero-stat-number {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: #ffffff;
}

.hero-stat-label {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-top: 4px;
}

/* ========== Features Section ========== */
.features {
  background: var(--color-primary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--gradient-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 36px 28px;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-cta);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: rgba(15, 130, 206, 0.3);
  box-shadow: var(--shadow-glow);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon {
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 130, 206, 0.1);
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
  font-size: 1.4rem;
  color: var(--color-highlight);
}

.feature-card h3 {
  font-size: 1.15rem;
  margin-bottom: 10px;
}

.feature-card p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

.features-cta {
  text-align: center;
  margin-top: 48px;
}

/* ========== Use Cases Section ========== */
.use-cases {
  background: var(--color-bg);
}

.use-cases-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.use-case-card {
  background: var(--gradient-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition-base);
}

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

.use-case-icon {
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  margin: 0 auto 20px;
  font-size: 1.6rem;
}

.use-case-card:nth-child(1) .use-case-icon {
  background: rgba(15, 130, 206, 0.12);
  color: var(--color-highlight);
}

.use-case-card:nth-child(2) .use-case-icon {
  background: rgba(103, 158, 189, 0.12);
  color: var(--color-muted);
}

.use-case-card:nth-child(3) .use-case-icon {
  background: rgba(208, 199, 204, 0.12);
  color: var(--color-accent);
}

.use-case-card:nth-child(4) .use-case-icon {
  background: rgba(15, 130, 206, 0.12);
  color: #4ecdc4;
}

.use-case-card h3 {
  font-size: 1.1rem;
  margin-bottom: 10px;
}

.use-case-card p {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  line-height: 1.7;
}

/* ========== Pricing Section ========== */
.pricing {
  background: var(--color-primary);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  align-items: start;
}

.pricing-card {
  background: var(--gradient-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  text-align: center;
  transition: all var(--transition-base);
  position: relative;
}

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

.pricing-card.popular {
  border-color: var(--color-highlight);
  box-shadow: 0 0 40px rgba(15, 130, 206, 0.15);
  transform: scale(1.04);
}

.pricing-card.popular:hover {
  transform: scale(1.04) translateY(-4px);
}

.pricing-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  padding: 6px 24px;
  background: var(--gradient-cta);
  color: #ffffff;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: 50px;
  white-space: nowrap;
}

.pricing-card h3 {
  font-size: 1.3rem;
  margin-bottom: 8px;
}

.pricing-card .pricing-desc {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 24px;
}

.pricing-price {
  margin-bottom: 28px;
}

.pricing-price .amount {
  font-size: 3rem;
  font-weight: 800;
  color: #ffffff;
}

.pricing-price .currency {
  font-size: 1.3rem;
  font-weight: 600;
  color: #ffffff;
  vertical-align: super;
}

.pricing-price .period {
  font-size: 1rem;
  color: var(--color-text-muted);
}

.pricing-features {
  margin-bottom: 32px;
  text-align: left;
}

.pricing-features li {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 0;
  font-size: 0.95rem;
  color: var(--color-text);
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

.pricing-features li:last-child {
  border-bottom: none;
}

.pricing-features li i.fa-check {
  color: var(--color-highlight);
  font-size: 0.85rem;
}

.pricing-features li i.fa-xmark {
  color: #555;
  font-size: 0.85rem;
}

.pricing-features li.disabled {
  color: var(--color-text-muted);
  opacity: 0.5;
}

.pricing-card .btn {
  width: 100%;
  justify-content: center;
}

/* ========== Testimonials Section ========== */
.testimonials {
  background: var(--color-bg);
}

.testimonials-header {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 40px;
  margin-bottom: 50px;
  flex-wrap: wrap;
}

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

.testimonials-stars {
  display: flex;
  gap: 4px;
  justify-content: center;
  margin-bottom: 8px;
}

.testimonials-stars i {
  color: #f4c542;
  font-size: 1.3rem;
}

.testimonials-score {
  font-size: 2.5rem;
  font-weight: 800;
  color: #ffffff;
}

.testimonials-count {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-top: 4px;
}

.testimonials-bars {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 200px;
}

.rating-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.rating-bar-fill {
  flex: 1;
  height: 6px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 3px;
  overflow: hidden;
}

.rating-bar-fill span {
  display: block;
  height: 100%;
  background: #f4c542;
  border-radius: 3px;
}

.testimonials-slider {
  overflow: hidden;
  position: relative;
}

.testimonials-track {
  display: flex;
  gap: 24px;
  transition: transform 0.5s ease;
}

.testimonial-card {
  min-width: calc(33.333% - 16px);
  background: var(--gradient-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 32px;
  flex-shrink: 0;
}

.testimonial-card .stars {
  display: flex;
  gap: 3px;
  margin-bottom: 16px;
}

.testimonial-card .stars i {
  color: #f4c542;
  font-size: 0.9rem;
}

.testimonial-card .text {
  color: var(--color-text);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 20px;
  font-style: italic;
}

.testimonial-card .author {
  display: flex;
  align-items: center;
  gap: 12px;
}

.testimonial-card .avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(15, 130, 206, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-highlight);
  font-weight: 700;
  font-size: 1rem;
}

.testimonial-card .author-name {
  font-weight: 600;
  color: #ffffff;
  font-size: 0.95rem;
}

.testimonial-card .author-title {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.slider-controls {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 32px;
}

.slider-btn {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--color-border);
  border-radius: 50%;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.slider-btn:hover {
  background: rgba(15, 130, 206, 0.15);
  border-color: var(--color-highlight);
  color: var(--color-highlight);
}

.testimonials-tags {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 36px;
  flex-wrap: wrap;
}

.testimonial-tag {
  padding: 8px 18px;
  background: rgba(15, 130, 206, 0.08);
  border: 1px solid rgba(15, 130, 206, 0.15);
  border-radius: 50px;
  color: var(--color-muted);
  font-size: 0.85rem;
}

/* ========== Comparison Section ========== */
.comparison {
  background: var(--color-primary);
}

.comparison-table-wrapper {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.comparison-table thead th {
  background: var(--color-secondary);
  padding: 18px 24px;
  text-align: center;
  font-weight: 600;
  color: #ffffff;
  border-bottom: 1px solid var(--color-border);
}

.comparison-table thead th:first-child {
  text-align: left;
}

.comparison-table thead th.highlight {
  background: rgba(15, 130, 206, 0.15);
  color: var(--color-highlight);
}

.comparison-table tbody td {
  padding: 16px 24px;
  text-align: center;
  border-bottom: 1px solid rgba(255, 255, 255, 0.03);
  color: var(--color-text-muted);
}

.comparison-table tbody td:first-child {
  text-align: left;
  font-weight: 500;
  color: var(--color-text);
}

.comparison-table tbody td.highlight {
  background: rgba(15, 130, 206, 0.05);
  color: var(--color-text);
}

.comparison-table tbody tr:hover {
  background: rgba(255, 255, 255, 0.02);
}

.comparison-table .check {
  color: var(--color-highlight);
  font-size: 1.1rem;
}

.comparison-table .cross {
  color: #555;
  font-size: 1.1rem;
}

/* ========== FAQ Section ========== */
.faq {
  background: var(--color-bg);
}

.faq-list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background: var(--gradient-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition-base);
}

.faq-item:hover {
  border-color: rgba(15, 130, 206, 0.2);
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  cursor: pointer;
  gap: 16px;
}

.faq-question h3 {
  font-size: 1.05rem;
  font-weight: 600;
}

.faq-question i {
  color: var(--color-highlight);
  font-size: 0.9rem;
  transition: transform var(--transition-base);
  flex-shrink: 0;
}

.faq-item.active .faq-question i {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s ease;
}

.faq-answer-inner {
  padding: 0 24px 20px;
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.8;
}

/* ========== Final CTA Section ========== */
.final-cta {
  padding: 100px 0;
  background: linear-gradient(135deg, #0f82ce 0%, #0a5f9e 40%, #151c2e 100%);
  position: relative;
  overflow: hidden;
}

.final-cta::before {
  content: '';
  position: absolute;
  top: -100px;
  right: -100px;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.05) 0%, transparent 70%);
  border-radius: 50%;
}

.final-cta .container {
  position: relative;
  z-index: 1;
  text-align: center;
}

.final-cta h2 {
  font-size: 2.75rem;
  margin-bottom: 16px;
}

.final-cta p {
  font-size: 1.2rem;
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 40px;
}

.final-cta .btn-primary {
  background: #ffffff;
  color: var(--color-highlight);
  font-size: 1.15rem;
  padding: 18px 48px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.final-cta .btn-primary:hover {
  background: #f0f0f0;
  transform: translateY(-3px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
  color: var(--color-highlight);
}

/* ========== Footer ========== */
.footer {
  background: var(--color-secondary);
  padding: 60px 0 0;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--color-border);
}

.footer-brand p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-top: 16px;
  line-height: 1.7;
  max-width: 320px;
}

.footer h4 {
  font-size: 1rem;
  margin-bottom: 20px;
  color: #ffffff;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--color-highlight);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 0;
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.footer-bottom-links {
  display: flex;
  gap: 24px;
}

.footer-bottom-links a {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.footer-bottom-links a:hover {
  color: var(--color-highlight);
}

/* ========== Back to Top ========== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-cta);
  color: #ffffff;
  border-radius: 50%;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-base);
  z-index: 999;
  border: none;
  font-size: 1.1rem;
}

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

.back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 25px rgba(15, 130, 206, 0.4);
}

/* ========== Animations ========== */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-on-scroll.animated {
  opacity: 1;
  transform: translateY(0);
}

.animate-on-scroll.delay-1 { transition-delay: 0.1s; }
.animate-on-scroll.delay-2 { transition-delay: 0.2s; }
.animate-on-scroll.delay-3 { transition-delay: 0.3s; }
.animate-on-scroll.delay-4 { transition-delay: 0.4s; }
.animate-on-scroll.delay-5 { transition-delay: 0.5s; }

/* ========== Mobile Navigation Overlay ========== */
.mobile-nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(14, 19, 33, 0.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  z-index: 999;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
}

.mobile-nav-overlay.active {
  display: flex;
}

.mobile-nav-overlay .nav-link {
  font-size: 1.3rem;
  padding: 12px 24px;
}

.mobile-nav-overlay .btn {
  margin-top: 16px;
  font-size: 1.1rem;
}

.mobile-nav-close {
  position: absolute;
  top: 20px;
  right: 24px;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  color: #ffffff;
  font-size: 1.5rem;
  cursor: pointer;
}

/* ========== Responsive ========== */
@media (max-width: 1024px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .use-cases-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .pricing-card.popular {
    transform: scale(1);
  }

  .pricing-card.popular:hover {
    transform: translateY(-4px);
  }

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .testimonial-card {
    min-width: calc(50% - 12px);
  }
}

@media (max-width: 768px) {
  .section {
    padding: 70px 0;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .nav {
    display: none;
  }

  .header-actions .btn {
    display: none;
  }

  .menu-toggle {
    display: flex;
  }

  .hero {
    padding: 120px 0 60px;
  }

  .hero h1 {
    font-size: 2.2rem;
  }

  .hero p {
    font-size: 1.05rem;
  }

  .hero-stats {
    gap: 24px;
    flex-wrap: wrap;
  }

  .hero-stat-number {
    font-size: 1.5rem;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .use-cases-grid {
    grid-template-columns: 1fr;
  }

  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 420px;
    margin: 0 auto;
  }

  .testimonial-card {
    min-width: calc(100% - 0px);
  }

  .testimonials-header {
    flex-direction: column;
    gap: 24px;
  }

  .comparison-table {
    font-size: 0.85rem;
  }

  .comparison-table thead th,
  .comparison-table tbody td {
    padding: 12px 14px;
  }

  .final-cta h2 {
    font-size: 2rem;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }

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

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.85rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .pricing-card {
    padding: 28px 20px;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 42px;
    height: 42px;
  }
}