/* ===== USDT下载入口 - 欧易交易所官方网站 主样式 ===== */
:root {
  --bg-primary: #0a0f18;
  --bg-secondary: #111827;
  --bg-card: #1a2235;
  --bg-card-hover: #1f2a3d;
  --usdt-green: #26a17b;
  --usdt-green-light: #2ecc9a;
  --tech-blue: #2775ca;
  --tech-blue-light: #3b8de0;
  --accent-orange: #f97316;
  --accent-orange-light: #fb923c;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: #1e293b;
  --border-light: #334155;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.5);
  --shadow-glow-green: 0 0 20px rgba(38, 161, 123, 0.3);
  --shadow-glow-blue: 0 0 20px rgba(39, 117, 202, 0.3);
  --shadow-glow-orange: 0 0 20px rgba(249, 115, 22, 0.3);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}

a {
  color: var(--tech-blue-light);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--usdt-green-light);
}

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

/* ===== Animations ===== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(40px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInLeft {
  from { opacity: 0; transform: translateX(-40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes fadeInRight {
  from { opacity: 0; transform: translateX(40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(38, 161, 123, 0.6); }
  50% { box-shadow: 0 0 0 18px rgba(38, 161, 123, 0); }
}

@keyframes pulseOrange {
  0%, 100% { box-shadow: 0 0 0 0 rgba(249, 115, 22, 0.6); }
  50% { box-shadow: 0 0 0 18px rgba(249, 115, 22, 0); }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-12px); }
}

@keyframes glow {
  0%, 100% { filter: drop-shadow(0 0 8px rgba(38, 161, 123, 0.4)); }
  50% { filter: drop-shadow(0 0 20px rgba(38, 161, 123, 0.8)); }
}

@keyframes scanLine {
  0% { top: -100%; }
  100% { top: 100%; }
}

@keyframes spinSlow {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

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

.fade-in-up {
  animation: fadeInUp 0.8s ease forwards;
  opacity: 0;
}

.fade-in-left {
  animation: fadeInLeft 0.8s ease forwards;
  opacity: 0;
}

.fade-in-right {
  animation: fadeInRight 0.8s ease forwards;
  opacity: 0;
}

.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ===== Navigation ===== */
header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(10, 15, 24, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
}

header nav {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  height: 68px;
}

.nav-brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--usdt-green);
  display: flex;
  align-items: center;
  gap: 8px;
  letter-spacing: 2px;
}

.nav-brand span {
  color: var(--text-primary);
  font-weight: 400;
  font-size: 0.85rem;
  letter-spacing: 0;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 8px;
  align-items: center;
}

.nav-links a {
  display: block;
  padding: 8px 18px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--usdt-green-light);
  background: rgba(38, 161, 123, 0.08);
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--usdt-green);
  border-radius: 1px;
}

.nav-cta {
  background: linear-gradient(135deg, var(--usdt-green), var(--usdt-green-light)) !important;
  color: #fff !important;
  padding: 8px 20px !important;
  border-radius: var(--radius-md) !important;
  font-weight: 600 !important;
  animation: pulse 2.5s infinite;
}

.nav-cta:hover {
  box-shadow: var(--shadow-glow-green) !important;
  transform: translateY(-1px) !important;
  background: linear-gradient(135deg, var(--usdt-green-light), var(--usdt-green)) !important;
  color: #fff !important;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  margin: 5px 0;
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== Hero ===== */
#hero {
  position: relative;
  min-height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: radial-gradient(ellipse at 50% 0%, rgba(38, 161, 123, 0.15) 0%, transparent 60%),
              radial-gradient(ellipse at 80% 80%, rgba(39, 117, 202, 0.1) 0%, transparent 60%);
}

#hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M30 5 L55 30 L30 55 L5 30Z' fill='none' stroke='%2326a17b' stroke-width='0.3' opacity='0.06'/%3E%3C/svg%3E") repeat;
  pointer-events: none;
}

.hero-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero-content h1 {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--text-primary) 30%, var(--usdt-green-light) 70%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-content h1 .highlight {
  display: block;
  font-size: 0.5em;
  font-weight: 600;
  -webkit-text-fill-color: var(--accent-orange);
  margin-bottom: 4px;
}

.hero-content p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  line-height: 1.8;
  max-width: 520px;
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

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

.btn-primary {
  background: linear-gradient(135deg, var(--usdt-green), #1e8a67);
  color: #fff;
  box-shadow: 0 4px 16px rgba(38, 161, 123, 0.35);
  animation: pulse 2.5s infinite;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(38, 161, 123, 0.5);
  color: #fff;
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-light);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--tech-blue);
  color: var(--tech-blue-light);
  transform: translateY(-2px);
}

.btn-orange {
  background: linear-gradient(135deg, var(--accent-orange), #e0650a);
  color: #fff;
  box-shadow: 0 4px 16px rgba(249, 115, 22, 0.35);
  animation: pulseOrange 2.5s infinite;
}

.btn-orange:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(249, 115, 22, 0.5);
  color: #fff;
}

.btn-lg {
  padding: 16px 40px;
  font-size: 1.1rem;
  border-radius: var(--radius-lg);
}

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.phone-mockup {
  position: relative;
  animation: float 4s ease-in-out infinite;
}

.phone-mockup img {
  border-radius: 30px;
  box-shadow: var(--shadow-lg), var(--shadow-glow-green);
  max-width: 280px;
  border: 3px solid rgba(38, 161, 123, 0.3);
}

.phone-float-ring {
  position: absolute;
  inset: -20px;
  border: 2px dashed rgba(38, 161, 123, 0.2);
  border-radius: 40px;
  animation: spinSlow 20s linear infinite;
}

.hero-badge {
  position: absolute;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 12px 18px;
  font-size: 0.85rem;
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(8px);
}

.hero-badge.top-right {
  top: 10%;
  right: -10%;
  color: var(--usdt-green-light);
  font-weight: 600;
}

.hero-badge.bottom-left {
  bottom: 15%;
  left: -5%;
  color: var(--accent-orange);
  font-weight: 600;
}

/* ===== Stats Bar ===== */
.stats-bar {
  max-width: var(--max-width);
  margin: -40px auto 60px;
  padding: 0 24px;
  position: relative;
  z-index: 2;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  box-shadow: var(--shadow-lg);
}

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

.stat-number {
  font-size: 2.2rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--usdt-green), var(--tech-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

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

/* ===== Section Common ===== */
section {
  padding: 80px 24px;
}

section h2 {
  font-size: 2.2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 16px;
  color: var(--text-primary);
}

section .section-subtitle {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 56px;
  font-size: 1.05rem;
}

/* ===== Features ===== */
#features {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px;
}

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

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

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--usdt-green), var(--tech-blue), var(--accent-orange));
  opacity: 0;
  transition: var(--transition);
}

.feature-card:hover {
  transform: translateY(-6px);
  border-color: var(--usdt-green);
  box-shadow: var(--shadow-glow-green);
  background: var(--bg-card-hover);
}

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

.feature-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 20px;
  background: rgba(38, 161, 123, 0.1);
  color: var(--usdt-green-light);
  transition: var(--transition);
}

.feature-card:nth-child(2) .feature-icon { background: rgba(39, 117, 202, 0.1); color: var(--tech-blue-light); }
.feature-card:nth-child(3) .feature-icon { background: rgba(249, 115, 22, 0.1); color: var(--accent-orange-light); }
.feature-card:nth-child(4) .feature-icon { background: rgba(38, 161, 123, 0.1); color: var(--usdt-green-light); }
.feature-card:nth-child(5) .feature-icon { background: rgba(39, 117, 202, 0.1); color: var(--tech-blue-light); }
.feature-card:nth-child(6) .feature-icon { background: rgba(249, 115, 22, 0.1); color: var(--accent-orange-light); }

.feature-card h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-primary);
}

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

/* ===== Download Section ===== */
#download {
  background: linear-gradient(180deg, var(--bg-primary), var(--bg-secondary), var(--bg-primary));
}

.download-container {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.download-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 30px;
  max-width: 720px;
  margin: 0 auto 40px;
}

.download-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 40px 28px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.download-card::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  border: 2px solid transparent;
  transition: var(--transition);
}

.download-card.android::after {
  border-color: rgba(38, 161, 123, 0.2);
}

.download-card.ios::after {
  border-color: rgba(39, 117, 202, 0.2);
}

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

.download-card.android:hover::after {
  border-color: var(--usdt-green);
  box-shadow: var(--shadow-glow-green);
}

.download-card.ios:hover::after {
  border-color: var(--tech-blue);
  box-shadow: var(--shadow-glow-blue);
}

.download-card .platform-icon {
  font-size: 3rem;
  margin-bottom: 16px;
}

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

.download-card p {
  color: var(--text-muted);
  margin-bottom: 20px;
  font-size: 0.9rem;
}

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

/* ===== CTA ===== */
#cta {
  background: linear-gradient(135deg, rgba(38, 161, 123, 0.08), rgba(39, 117, 202, 0.08));
}

.cta-container {
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
  padding: 60px 24px;
}

.cta-container h2 {
  font-size: 2rem;
  margin-bottom: 12px;
}

.cta-container p {
  color: var(--text-secondary);
  margin-bottom: 28px;
  font-size: 1.05rem;
}

.cta-buttons {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== About Page ===== */
.about-hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px 40px;
  text-align: center;
}

.about-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
}

.about-hero .subtitle {
  color: var(--text-muted);
  max-width: 650px;
  margin: 0 auto;
  font-size: 1.05rem;
}

.about-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px 80px;
  display: grid;
  gap: 40px;
}

.about-section {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px;
}

.about-section h2 {
  text-align: left;
  font-size: 1.5rem;
  margin-bottom: 20px;
  color: var(--usdt-green-light);
}

.about-section p {
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 14px;
}

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

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--usdt-green), var(--tech-blue), var(--accent-orange));
  border-radius: 1px;
}

.timeline-item {
  position: relative;
  margin-bottom: 28px;
  padding-left: 20px;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -24px;
  top: 6px;
  width: 12px;
  height: 12px;
  background: var(--usdt-green);
  border-radius: 50%;
  border: 3px solid var(--bg-card);
}

.timeline-item:nth-child(even)::before { background: var(--tech-blue); }

.timeline-year {
  font-size: 0.85rem;
  color: var(--usdt-green-light);
  font-weight: 700;
}

.timeline-item h3 {
  font-size: 1.1rem;
  margin: 4px 0 6px;
}

.timeline-item p {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 0;
}

.security-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.security-item {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 24px;
  text-align: center;
}

.security-item .icon {
  font-size: 2rem;
  margin-bottom: 12px;
}

.security-item h4 {
  font-size: 1rem;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.security-item p {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin: 0;
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.team-card {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 24px;
  text-align: center;
  transition: var(--transition);
}

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

.team-card img {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  margin: 0 auto 12px;
  border: 2px solid var(--usdt-green);
}

.team-card h4 {
  font-size: 1rem;
  margin-bottom: 2px;
}

.team-card .role {
  font-size: 0.8rem;
  color: var(--usdt-green-light);
}

/* ===== Services Page ===== */
.services-hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px 40px;
  text-align: center;
}

.services-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
}

.services-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px 80px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.service-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  transition: var(--transition);
}

.service-card:hover {
  transform: translateY(-4px);
  border-color: var(--usdt-green);
  box-shadow: var(--shadow-glow-green);
}

.service-card .icon {
  font-size: 2.2rem;
  margin-bottom: 16px;
  display: block;
}

.service-card h3 {
  font-size: 1.2rem;
  margin-bottom: 10px;
}

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

.service-card .btn {
  margin-top: 16px;
  padding: 10px 20px;
  font-size: 0.9rem;
}

.services-table {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px 80px;
}

.services-table h2 {
  margin-bottom: 28px;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.comparison-table th,
.comparison-table td {
  padding: 16px 20px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.comparison-table th {
  background: var(--bg-secondary);
  font-weight: 600;
  color: var(--usdt-green-light);
  font-size: 0.9rem;
}

.comparison-table td {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.comparison-table tr:last-child td {
  border-bottom: none;
}

.comparison-table .check {
  color: var(--usdt-green);
  font-weight: 600;
}

/* ===== FAQ Page ===== */
.faq-hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px 40px;
  text-align: center;
}

.faq-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
}

.faq-search {
  max-width: 500px;
  margin: 24px auto 0;
  position: relative;
}

.faq-search input {
  width: 100%;
  padding: 14px 20px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: var(--transition);
}

.faq-search input:focus {
  outline: none;
  border-color: var(--usdt-green);
  box-shadow: var(--shadow-glow-green);
}

.faq-search input::placeholder {
  color: var(--text-muted);
}

.faq-container {
  max-width: 850px;
  margin: 0 auto;
  padding: 0 24px 80px;
}

.faq-category {
  margin-bottom: 48px;
}

.faq-category h2 {
  text-align: left;
  font-size: 1.4rem;
  margin-bottom: 16px;
  color: var(--usdt-green-light);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-color);
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 10px;
  transition: var(--transition);
  overflow: hidden;
}

.faq-item:hover {
  border-color: var(--tech-blue);
}

.faq-item summary {
  padding: 18px 24px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1rem;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: var(--transition);
}

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

.faq-item summary::after {
  content: '+';
  font-size: 1.4rem;
  color: var(--usdt-green);
  font-weight: 300;
  transition: transform 0.3s ease;
}

.faq-item[open] summary::after {
  content: '−';
  transform: rotate(180deg);
}

.faq-item[open] summary {
  color: var(--usdt-green-light);
  background: rgba(38, 161, 123, 0.05);
}

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

.faq-category-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 36px;
}

.faq-cat-btn {
  padding: 8px 18px;
  border-radius: 20px;
  border: 1px solid var(--border-light);
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
}

.faq-cat-btn:hover,
.faq-cat-btn.active {
  background: var(--usdt-green);
  border-color: var(--usdt-green);
  color: #fff;
}

/* ===== Contact Page ===== */
.contact-hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px 40px;
  text-align: center;
}

.contact-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
}

.contact-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px 80px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 36px;
}

.contact-form-section {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px;
}

.contact-form-section h2 {
  text-align: left;
  font-size: 1.4rem;
  margin-bottom: 24px;
  color: var(--usdt-green-light);
}

.form-group {
  margin-bottom: 18px;
}

.form-group label {
  display: block;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text-secondary);
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: var(--transition);
  font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--usdt-green);
  box-shadow: var(--shadow-glow-green);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

.contact-info-section {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.contact-info-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: var(--transition);
}

.contact-info-card:hover {
  border-color: var(--tech-blue);
  box-shadow: var(--shadow-glow-blue);
}

.contact-info-card h3 {
  font-size: 1.1rem;
  margin-bottom: 14px;
  color: var(--usdt-green-light);
}

.contact-info-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
}

.contact-info-card .info-item {
  display: flex;
  gap: 10px;
  margin-bottom: 8px;
  align-items: flex-start;
}

.contact-info-card .info-item .label {
  color: var(--text-muted);
  min-width: 60px;
  font-size: 0.85rem;
}

.social-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.social-link {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
  color: var(--text-secondary);
  font-size: 0.85rem;
  transition: var(--transition);
}

.social-link:hover {
  border-color: var(--usdt-green);
  color: var(--usdt-green-light);
  background: rgba(38, 161, 123, 0.08);
}

/* ===== Footer ===== */
footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 48px 24px 28px;
}

.footer-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 36px;
}

.footer-col h4 {
  font-size: 1rem;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.footer-col p {
  color: var(--text-muted);
  font-size: 0.85rem;
  line-height: 1.6;
}

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

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

.footer-col ul li a {
  color: var(--text-muted);
  font-size: 0.85rem;
  transition: var(--transition);
}

.footer-col ul li a:hover {
  color: var(--usdt-green-light);
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 36px auto 0;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .hero-grid {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 36px;
  }
  .hero-content p {
    margin: 0 auto 32px;
  }
  .hero-buttons {
    justify-content: center;
  }
  .features-grid,
  .services-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .security-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .team-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .contact-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    flex-direction: column;
    padding: 16px;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
  }
  .nav-links.open {
    display: flex;
  }
  .nav-toggle {
    display: block;
  }
  .features-grid,
  .services-grid {
    grid-template-columns: 1fr;
  }
  .security-grid {
    grid-template-columns: 1fr;
  }
  .team-grid {
    grid-template-columns: 1fr 1fr;
  }
  .stats-grid {
    grid-template-columns: 1fr 1fr;
  }
  .download-cards {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  section {
    padding: 48px 16px;
  }
  .about-hero,
  .services-hero,
  .faq-hero,
  .contact-hero {
    padding-top: 48px;
  }
  section h2 {
    font-size: 1.6rem;
  }
  .hero-content h1 {
    font-size: 1.8rem;
  }
  .comparison-table {
    font-size: 0.8rem;
  }
  .comparison-table th,
  .comparison-table td {
    padding: 10px 12px;
  }
}

@media (max-width: 480px) {
  .hero-buttons {
    flex-direction: column;
  }
  .btn {
    width: 100%;
    justify-content: center;
  }
  .cta-buttons {
    flex-direction: column;
  }
  .team-grid {
    grid-template-columns: 1fr;
  }
}