:root {
  --color-primary: #0d2240;
  --color-secondary: #1a4a7a;
  --color-accent: #0096cc;
  --color-accent-2: #00b4d0;
  --color-bg: #f0f5fa;
  --color-bg-alt: #e6eef6;
  --color-card: #ffffff;
  --color-text: #1a2c3d;
  --color-text-muted: #5a7a95;
  --color-border: #cddaeb;
  --color-success: #10a870;
  --color-warning: #f59e0b;
  --color-danger: #e05252;

  --font-main: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  --radius: 12px;
  --shadow: 0 4px 16px rgba(13, 34, 64, 0.12);
  --transition: all 0.3s ease;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-main);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 2rem; }
a { color: var(--color-accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-accent-2); }

#scroll-progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-2));
  z-index: 9999;
  transition: width 0.1s linear;
}

#main-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  background: rgba(13, 34, 64, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 150, 204, 0.15);
  z-index: 1000;
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 2rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: white;
}

.nav-logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav-logo-icon svg { width: 18px; height: 18px; fill: white; }

.nav-logo-text strong { font-size: 0.95rem; font-weight: 800; letter-spacing: 0.05em; }
.nav-logo-text small { font-size: 0.6rem; color: rgba(255,255,255,0.6); letter-spacing: 0.08em; }

.nav-menu {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.nav-menu a {
  font-size: 0.85rem;
  font-weight: 600;
  color: rgba(255,255,255,0.7);
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  transition: background var(--transition), color var(--transition);
}

.nav-menu a:hover, .nav-menu a.active {
  color: white;
  background: rgba(0, 150, 204, 0.2);
}

.nav-hamburger { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; }
.nav-hamburger span { width: 22px; height: 2px; background: white; border-radius: 2px; }
.nav-mobile { display: none; flex-direction: column; gap: 0.5rem; padding: 1rem 2rem; background: rgba(13, 34, 64, 0.98); border-top: 1px solid rgba(0, 150, 204, 0.15); }
.nav-mobile.open { display: flex; }
.nav-mobile a { color: rgba(255,255,255,0.7); padding: 0.6rem; border-radius: 6px; }
.nav-mobile a:hover { background: rgba(0, 150, 204, 0.15); color: white; }

.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 80px;
  padding-bottom: 80px;
  background-attachment: fixed;
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(8, 23, 43, 0.75);
  z-index: -1;
}

.hero-content {
  position: relative;
  z-index: 1;
  color: white;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.gate-badge {
  display: inline-block;
  background: rgba(0, 150, 204, 0.2);
  border: 1px solid rgba(0, 150, 204, 0.4);
  color: #64d0f0;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  margin-bottom: 1.5rem;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(1.6rem, 4vw, 2.8rem);
  font-weight: 900;
  line-height: 1.3;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, #ffffff, #64d0f0);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.01em;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.hero h2 {
  display: none;
}

.hero-lead {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.75);
  margin-bottom: 2.5rem;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn-primary, .btn-outline {
  padding: 1rem 1.75rem;
  font-size: 0.95rem;
  font-weight: 700;
  border-radius: 8px;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  color: white;
  box-shadow: 0 8px 24px rgba(0, 150, 204, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(0, 150, 204, 0.5);
}

.btn-outline {
  background: transparent;
  border: 1.5px solid rgba(255,255,255,0.25);
  color: rgba(255,255,255,0.85);
}

.btn-outline:hover {
  border-color: var(--color-accent);
  color: white;
  background: rgba(0, 150, 204, 0.1);
}

.section-light { background: var(--color-bg); padding: 5rem 0; }
.section-dark { background: var(--color-primary); color: white; padding: 5rem 0; }
.section-dark a { color: var(--color-accent-2); }

.section-title {
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 900;
  margin-bottom: 1.6rem;
  text-align: center;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.section-dark .section-title { color: white; }

.section-lead {
  max-width: 860px;
  margin: 0 auto 2.4rem;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.98rem;
}

#download .section-lead { margin: 0 auto 2.2rem; }

.section-dark .section-lead { color: rgba(255,255,255,0.65); }

.quick-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
}

.trust-badges {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.trust-badge {
  display: flex;
  gap: 0.9rem;
  align-items: center;
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 1rem 1.1rem;
}

.trust-badge img {
  width: 36px;
  height: 36px;
}

.trust-badge strong {
  display: block;
  font-size: 0.95rem;
  color: var(--color-primary);
}

.trust-badge span {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.download-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  box-shadow: var(--shadow);
}

.download-head {
  display: flex;
  gap: 0.9rem;
  align-items: center;
}

.download-logo {
  width: 52px;
  height: 52px;
  object-fit: contain;
  border-radius: 10px;
  background: var(--color-bg);
  padding: 0.4rem;
}

.download-title {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--color-primary);
}

.download-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.download-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.7rem 0.8rem;
  border-radius: 8px;
  background: rgba(0, 150, 204, 0.12);
  border: 1px solid rgba(0, 150, 204, 0.25);
  color: var(--color-primary);
  font-weight: 700;
  font-size: 0.9rem;
  transition: var(--transition);
  text-decoration: none;
}

.download-btn::before {
  content: '';
  width: 18px;
  height: 18px;
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center;
  display: inline-block;
}

.download-btn.android::before { background-image: url('assets/icons/os-android.svg'); }
.download-btn.ios::before { background-image: url('assets/icons/os-ios.svg'); }

.download-btn:hover {
  background: rgba(0, 150, 204, 0.2);
  border-color: rgba(0, 150, 204, 0.5);
}

.download-btn.disabled {
  background: rgba(0,0,0,0.04);
  border-color: rgba(0,0,0,0.08);
  color: var(--color-text-muted);
  cursor: not-allowed;
  pointer-events: none;
}

.download-btn.disabled::before { filter: grayscale(1); opacity: 0.5; }

.download-note {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.verify-panel {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
}

.verify-panel h3 {
  margin-bottom: 0.8rem;
  font-size: 1.05rem;
  color: var(--color-primary);
}

.verify-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.verify-list li {
  position: relative;
  padding-left: 1.4rem;
  color: var(--color-text-muted);
}

.verify-list li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--color-success);
  font-weight: 700;
}

.quick-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  text-align: center;
  transition: var(--transition);
}

.quick-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: var(--color-accent);
}

.quick-icon { font-size: 2.5rem; display: block; margin-bottom: 1rem; }
.quick-card h3 { font-size: 1.1rem; margin-bottom: 0.5rem; color: var(--color-primary); }
.quick-card p { font-size: 0.9rem; color: var(--color-text-muted); }

.hw-sw-comparison {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-bottom: 3rem;
}

.hw-card, .sw-card {
  background: var(--color-card);
  border-radius: var(--radius);
  padding: 2rem;
  border: 1px solid var(--color-border);
}

.section-dark .hw-card,
.section-dark .sw-card {
  background: rgba(255,255,255,0.05);
  border-color: rgba(255,255,255,0.1);
}

.hw-image, .sw-image {
  width: 100%;
  height: 250px;
  background: linear-gradient(135deg, #f0f5fa, #e6eef6);
  border-radius: 8px;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.section-dark .hw-image,
.section-dark .sw-image {
  background: rgba(255,255,255,0.05);
}

.hw-image img, .sw-image img {
  max-width: 90%;
  max-height: 90%;
  object-fit: contain;
}

.hw-card h3, .sw-card h3 {
  font-size: 1.3rem;
  margin-bottom: 1.25rem;
  font-weight: 800;
}

.feature-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.feature {
  font-size: 0.95rem;
  line-height: 1.5;
}

.hw-card .feature:nth-child(-n+4) { color: var(--color-success); }
.hw-card .feature:nth-child(n+5) { color: var(--color-text-muted); }
.sw-card .feature:nth-child(-n+4) { color: var(--color-success); }
.sw-card .feature:nth-child(n+5) { color: var(--color-text-muted); }

.example { font-size: 0.9rem; color: var(--color-text-muted); font-style: italic; }

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

.section-dark .table-wrapper {
  border-color: rgba(255,255,255,0.1);
}

.comparison-table, .chain-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--color-card);
}

.section-dark .comparison-table,
.section-dark .chain-table {
  background: rgba(255,255,255,0.02);
}

.comparison-table th, .chain-table th {
  background: var(--color-primary);
  color: white;
  padding: 1rem;
  text-align: left;
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.comparison-table td, .chain-table td {
  padding: 0.9rem 1rem;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.95rem;
}

.section-dark .comparison-table td,
.section-dark .chain-table td {
  border-color: rgba(255,255,255,0.05);
}

.comparison-table tr:nth-child(even),
.chain-table tr:nth-child(even) {
  background: rgba(0, 150, 204, 0.04);
}

.section-dark .comparison-table tr:nth-child(even),
.section-dark .chain-table tr:nth-child(even) {
  background: rgba(255,255,255,0.02);
}

.table-legend {
  text-align: center;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-top: 1.5rem;
}

.wallet-cards {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.wallet-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
  transition: var(--transition);
}

.wallet-card:hover {
  box-shadow: var(--shadow);
  border-color: var(--color-accent);
}

.wallet-card.featured {
  border: 2px solid var(--color-accent);
  background: linear-gradient(135deg, #ffffff 98%, rgba(0, 150, 204, 0.02));
}

.wallet-header {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.wallet-logo {
  width: 64px;
  height: 64px;
  object-fit: contain;
  border-radius: 8px;
  background: var(--color-bg);
  padding: 0.5rem;
}

.wallet-info {
  flex: 1;
}

.wallet-info h3 {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
  font-weight: 800;
  color: var(--color-primary);
}

.wallet-type {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
}

.wallet-type.hw {
  background: rgba(99, 102, 241, 0.1);
  color: #6366f1;
}

.wallet-type.sw {
  background: rgba(16, 168, 112, 0.1);
  color: var(--color-success);
}

.wallet-score {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  text-align: right;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.wallet-detail p {
  margin-bottom: 1rem;
  line-height: 1.75;
  font-size: 0.9rem;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.pros-cons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin: 1.5rem 0;
  padding: 1.5rem;
  background: var(--color-bg);
  border-radius: 8px;
}

.pros, .cons {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.pros h4 { color: var(--color-success); font-size: 0.9rem; font-weight: 700; margin-bottom: 0.5rem; }
.cons h4 { color: var(--color-danger); font-size: 0.9rem; font-weight: 700; margin-bottom: 0.5rem; }

.pros ul, .cons ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.pros li, .cons li {
  font-size: 0.9rem;
  line-height: 1.5;
  padding-left: 1.5rem;
  position: relative;
}

.pros li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--color-success);
  font-weight: 700;
}

.cons li::before {
  content: '✗';
  position: absolute;
  left: 0;
  color: var(--color-danger);
  font-weight: 700;
}

.best-for, .platforms {
  font-size: 0.95rem;
  padding: 0.75rem;
  background: rgba(0, 150, 204, 0.08);
  border-radius: 6px;
  margin-bottom: 0.75rem;
}

.best-for strong, .platforms strong {
  color: var(--color-primary);
}

.tutorial-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
  border-bottom: 2px solid var(--color-border);
}

.section-dark .tutorial-tabs {
  border-color: rgba(255,255,255,0.1);
}

.tab-btn {
  padding: 1rem 1.25rem;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-muted);
  position: relative;
  transition: color var(--transition);
}

.section-dark .tab-btn {
  color: rgba(255,255,255,0.5);
}

.tab-btn:hover, .tab-btn.active {
  color: var(--color-accent);
}

.section-dark .tab-btn:hover,
.section-dark .tab-btn.active {
  color: var(--color-accent-2);
}

.tab-btn.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-accent);
}

.section-dark .tab-btn.active::after {
  background: var(--color-accent-2);
}

.tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.tab-content h3 {
  font-size: 1.3rem;
  margin-bottom: 1.5rem;
  color: var(--color-primary);
}

.section-dark .tab-content h3 {
  color: #00e0ff;
}

.section-dark .tab-content h4 {
  color: #10d981;
  font-weight: 600;
}

.section-dark .tab-content h5 {
  color: #10d981;
}

.section-dark .tab-content p {
  color: #e8f0ff;
  line-height: 1.7;
}

.section-dark .tab-content ul {
  color: #e8f0ff;
}

.section-dark .tab-content li {
  color: #e8f0ff;
  margin-bottom: 0.5rem;
}

.steps {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.step {
  display: grid;
  grid-template-columns: 50px 1fr;
  gap: 1.5rem;
  padding: 1.5rem;
  background: var(--color-bg);
  border-radius: 8px;
  border-left: 4px solid var(--color-accent);
}

.section-dark .step {
  background: rgba(255,255,255,0.05);
  border-left-color: var(--color-accent-2);
}

.step-num {
  width: 50px;
  height: 50px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  color: white;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  font-size: 1.25rem;
  flex-shrink: 0;
}

.step-content h4 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
  color: var(--color-primary);
  word-break: break-word;
}

.section-dark .step-content h4 {
  color: #10d981;
}

.step-content p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.section-dark .step-content p {
  color: rgba(255,255,255,0.85);
}

.flow-diagram {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
  align-items: center;
}

.flow-box {
  background: linear-gradient(135deg, #f0f5fa, #e6eef6);
  border-radius: 8px;
  padding: 1.25rem;
  text-align: center;
  border: 1px solid var(--color-border);
}

.section-dark .flow-box {
  background: linear-gradient(135deg, rgba(255,255,255,0.05), rgba(255,255,255,0.08));
  border-color: rgba(255,255,255,0.1);
}

.box-title {
  font-size: 0.85rem;
  font-weight: 800;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
  letter-spacing: 0.05em;
}

.section-dark .box-title {
  color: white;
}

.box-content {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  line-height: 1.5;
}

.section-dark .box-content {
  color: rgba(255,255,255,0.6);
}

.flow-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--color-accent);
  font-weight: bold;
}

.concept-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.concept-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  word-wrap: break-word;
  overflow-wrap: break-word;
  min-height: auto;
}

.section-dark .concept-card {
  background: rgba(255,255,255,0.05);
  border-color: rgba(255,255,255,0.1);
}

.concept-card h3 {
  font-size: 1rem;
  margin-bottom: 0.75rem;
  color: var(--color-primary);
  font-weight: 800;
  word-break: break-word;
}

.section-dark .concept-card h3 {
  color: white;
}

.concept-card p {
  font-size: 0.85rem;
  margin-bottom: 0.6rem;
  line-height: 1.55;
  color: var(--color-text-muted);
  word-break: break-word;
}

.section-dark .concept-card p {
  color: rgba(255,255,255,0.65);
}

.concept-card strong {
  color: var(--color-primary);
  word-break: break-word;
}

.section-dark .concept-card strong {
  color: var(--color-accent-2);
}

.security-checklist {
  background: var(--color-bg);
  border-left: 4px solid var(--color-accent);
  padding: 1.5rem;
  border-radius: 8px;
  margin-top: 2rem;
}

.section-dark .security-checklist {
  background: rgba(255,255,255,0.05);
  border-left-color: var(--color-accent-2);
}

.security-checklist h3 {
  margin-bottom: 1rem;
  color: var(--color-primary);
}

.section-dark .security-checklist h3 {
  color: white;
}

.checklist {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.checklist li {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

.section-dark .checklist li {
  color: rgba(255,255,255,0.65);
}

.scenario-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.scenario {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
  transition: var(--transition);
}

.scenario:hover {
  box-shadow: var(--shadow);
  border-color: var(--color-accent);
  transform: translateY(-3px);
}

.scenario h3 {
  font-size: 1.1rem;
  margin-bottom: 1rem;
  color: var(--color-primary);
  font-weight: 800;
}

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

.scenario strong {
  color: var(--color-accent);
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

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

.section-dark .faq-item {
  background: rgba(255,255,255,0.04);
  border-color: rgba(255,255,255,0.1);
}

.faq-item summary {
  padding: 1.5rem;
  cursor: pointer;
  font-weight: 600;
  color: var(--color-primary);
  user-select: none;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-dark .faq-item summary {
  color: white;
}

.faq-item summary::before {
  content: '▶';
  font-size: 0.8rem;
  display: inline-block;
  transition: transform var(--transition);
}

.faq-item[open] summary::before {
  transform: rotate(90deg);
}

.faq-item p, .faq-item ul {
  padding: 0 1.5rem 1.5rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.75;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.section-dark .faq-item p,
.section-dark .faq-item ul {
  color: rgba(255,255,255,0.65);
}

.faq-item ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.faq-item li {
  padding-left: 1.5rem;
  position: relative;
}

.faq-item li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: bold;
}

.faq-items {
  background: var(--color-bg);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-top: 1.5rem;
}

.section-dark .faq-items {
  background: rgba(255,255,255,0.04);
}

.faq-items h4 {
  margin-top: 1rem;
  margin-bottom: 0.75rem;
  font-weight: 700;
  color: var(--color-primary);
}

.section-dark .faq-items h4 {
  color: white;
}

.faq-items ul {
  list-style: none;
  padding-left: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.faq-items li {
  font-size: 0.9rem;
  padding-left: 1rem;
  position: relative;
  line-height: 1.6;
}

.faq-items li::before {
  content: '•';
  position: absolute;
  left: 0.3rem;
  color: var(--color-text-muted);
}

.footer-section {
  background: var(--color-primary);
  color: white;
  padding: 4rem 0 2rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-col h4 {
  font-size: 1.05rem;
  margin-bottom: 1rem;
  font-weight: 800;
  letter-spacing: 0.05em;
}

.footer-col p {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.65);
  line-height: 1.7;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-col a {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.7);
  transition: color var(--transition);
}

.footer-col a:hover {
  color: var(--color-accent-2);
}

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: 0.85rem;
  color: rgba(255,255,255,0.5);
}

#back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 1.5rem;
  cursor: pointer;
  transition: var(--transition);
  opacity: 0;
  pointer-events: none;
  z-index: 900;
}

#back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

#back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(0, 150, 204, 0.35);
}

@media (max-width: 900px) {
  .nav-menu { display: none; }
  .nav-hamburger { display: flex; }
  .nav-mobile.open { display: flex; }

  .hw-sw-comparison { grid-template-columns: 1fr; }
  .scenario-cards { grid-template-columns: 1fr; }
  .concept-cards { grid-template-columns: 1fr; }
  .pros-cons { grid-template-columns: 1fr; }

  .flow-diagram { grid-template-columns: 1fr; }
  .flow-arrow { transform: rotate(90deg); margin: 0; }
}

@media (max-width: 600px) {
  .container { padding: 0 1rem; }
  .section-light, .section-dark { padding: 3rem 0; }

  .hero { padding-top: 100px; padding-bottom: 2rem; }
  .hero h1 { font-size: 1.5rem; }

  .quick-cards { grid-template-columns: 1fr; }
  .tutorial-tabs { flex-direction: column; }
  .tab-btn { width: 100%; text-align: left; }
  .tab-btn.active::after { display: none; }
  .tab-btn.active { background: rgba(0, 150, 204, 0.15); }

  .wallet-header { grid-template-columns: 1fr; }
  .wallet-score { text-align: left; }

  #back-to-top { width: 40px; height: 40px; font-size: 1.2rem; }
  .download-actions { grid-template-columns: 1fr; }
}