:root {

  --color-bg: #f8f9fb;
  --color-bg-section: #ffffff;
  --color-bg-dark: #1e2732;
  --color-nav: #252f3d;
  --color-nav-hover: #2d3a4a;
  --color-nav-active: #0f4c81;

  --color-text: #2c3e50;
  --color-text-muted: #5a6c7d;
  --color-text-light: #8a9ba8;
  --color-text-on-dark: #e8ecf0;
  --color-text-on-dark-muted: #a8b5c4;

  --color-accent: #0f6db5;
  --color-accent-light: #3a8fd4;
  --color-accent-muted: #e3eef6;

  --color-border: #e2e8ef;
  --color-border-dark: #3d4a5c;
  --color-divider: #d1dce6;

  --color-tag: #5a7a94;
  --color-tag-bg: #e8eef4;
  --color-alert: #b85450;
  --color-alert-bg: #fdf2f2;

  --nav-width: 260px;
  --content-max: 900px;
  --content-padding: 2.5rem;
  --section-gap: 4rem;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", "Consolas", "Monaco", monospace;

  --shadow-sm: 0 1px 3px rgba(15, 76, 129, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 76, 129, 0.08);

  --transition-fast: 0.2s ease;
  --transition-smooth: 0.35s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  display: flex;
  min-height: 100vh;
  overflow-x: hidden;
}

.nav-sidebar {
  position: fixed;
  left: 0;
  top: 0;
  width: var(--nav-width);
  height: 100vh;
  background: var(--color-nav);
  color: var(--color-text-on-dark);
  display: flex;
  flex-direction: column;
  z-index: 100;
  box-shadow: 4px 0 24px rgba(0, 0, 0, 0.12);
  transition: transform var(--transition-smooth);
}

.nav-header {
  padding: 1.5rem 1.25rem;
  border-bottom: 1px solid var(--color-border-dark);
  flex-shrink: 0;
}

.nav-subtitle {
  margin: 0.5rem 0 0 0;
  font-size: 0.75rem;
  color: var(--color-text-on-dark-muted);
  font-weight: 400;
  letter-spacing: 0.03em;
}

.nav-dir-title {
  padding: 0 1rem 0.75rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-text-light);
  opacity: 0.9;
}

.nav-archive .nav-link {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.6rem 0.85rem;
}

.nav-footer-icon {
  margin-bottom: 0.35rem;
}

.nav-footer-icon img {
  filter: brightness(0) invert(1);
  opacity: 0.7;
}

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

.nav-logo-img {
  width: 36px;
  height: 36px;
  object-fit: contain;
  opacity: 0.95;
  filter: brightness(0) invert(1);
}

.nav-logo-img.nav-logo-bitpie {
  filter: none;
  width: 112px;
  height: 112px;
}

.nav-dir {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 0;
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0 0.75rem;
}

.nav-list li {
  margin-bottom: 0.25rem;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.6rem 0.85rem;
  color: var(--color-text-on-dark-muted);
  text-decoration: none;
  font-size: 0.9rem;
  border-radius: 6px;
  transition: all var(--transition-fast);
}

.nav-link:hover {
  color: var(--color-text-on-dark);
  background: var(--color-nav-hover);
  transform: translateX(4px);
}

.nav-link.active {
  color: #fff;
  background: var(--color-nav-active);
  box-shadow: 0 2px 8px rgba(15, 76, 129, 0.3);
}

.nav-icon {
  flex-shrink: 0;
  opacity: 0.85;
  filter: brightness(0) invert(1);
}

.nav-link.active .nav-icon {
  opacity: 1;
}

.nav-footer {
  padding: 1.25rem 1.25rem;
  border-top: 1px solid var(--color-border-dark);
  flex-shrink: 0;
}

.nav-footer-text {
  margin: 0 0 0.25rem 0;
  font-size: 0.8rem;
  color: var(--color-text-on-dark-muted);
}

.nav-footer-sub {
  margin: 0;
  font-size: 0.75rem;
  color: var(--color-text-light);
  opacity: 0.8;
}

.nav-toggle-close {
  display: none;
  position: absolute;
  top: 1rem;
  right: 1rem;
  width: 36px;
  height: 36px;
  border: none;
  background: transparent;
  color: var(--color-text-on-dark);
  font-size: 1.5rem;
  cursor: pointer;
  line-height: 1;
}

.nav-toggle-open {
  display: none;
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 101;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  width: 48px;
  height: 48px;
  background: var(--color-nav);
  color: var(--color-text-on-dark);
  border: none;
  border-radius: 10px;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  gap: 6px;
  transition: background var(--transition-fast), transform var(--transition-fast);
}

.nav-toggle-open:hover {
  background: var(--color-nav-hover);
}

.nav-toggle-open:active {
  transform: scale(0.96);
}

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-toggle-open.open .nav-toggle-bar:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.nav-toggle-open.open .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle-open.open .nav-toggle-bar:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

.content-main {
  flex: 1;
  margin-left: var(--nav-width);
  padding: 2rem var(--content-padding) 4rem;
  max-width: calc(100vw - var(--nav-width));
}

.archive-entry {
  max-width: var(--content-max);
  margin: 0 auto 4rem;
  padding: 3rem 0;
  border-bottom: 1px solid var(--color-divider);
}

.entry-label {
  display: inline-block;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  margin-bottom: 1rem;
  letter-spacing: 0.05em;
}

.archive-entry h1 {
  font-size: 2rem;
  font-weight: 600;
  margin: 0 0 1.25rem 0;
  color: var(--color-text);
  letter-spacing: 0.01em;
}

.entry-summary {
  font-size: 1.05rem;
  line-height: 1.75;
  color: var(--color-text-muted);
  margin: 0 0 1.5rem 0;
}

.entry-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.meta-tag {
  font-size: 0.8rem;
  padding: 0.35rem 0.75rem;
  background: var(--color-tag-bg);
  color: var(--color-tag);
  border-radius: 4px;
}

.entry-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.btn-primary {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-light) 100%);
  color: #fff;
  text-decoration: none;
  border-radius: 8px;
  font-size: 0.95rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 4px 12px rgba(15, 76, 129, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(15, 76, 129, 0.4);
}

.btn-secondary {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  background: transparent;
  color: var(--color-accent);
  text-decoration: none;
  border: 2px solid var(--color-accent);
  border-radius: 8px;
  font-size: 0.95rem;
  transition: all 0.2s ease;
}

.btn-secondary:hover {
  background: var(--color-accent-muted);
  transform: translateY(-2px);
}

.entry-note {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin: 0;
}

.archive-section {
  max-width: var(--content-max);
  margin: 0 auto var(--section-gap);
  padding: 2.5rem 2rem;
  background: var(--color-bg-section);
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.04);
  border: 1px solid var(--color-border);
  transition: box-shadow 0.3s ease, transform 0.3s ease;
}

.archive-section:hover {
  box-shadow: 0 8px 32px rgba(15, 76, 129, 0.08);
}

.archive-section-dark {
  background: #f2f5f8;
  border-color: var(--color-divider);
}

.section-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8rem;
  color: var(--color-tag);
  font-family: var(--font-mono);
  margin-bottom: 1rem;
  letter-spacing: 0.04em;
}

.section-icon {
  opacity: 0.9;
}

.archive-section h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0 0 1rem 0;
  color: var(--color-text);
}

.section-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0 0 2rem 0;
  line-height: 1.7;
}

.brand-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.brand-card {
  padding: 1.5rem;
  background: var(--color-bg);
  border-radius: 10px;
  border-left: 4px solid var(--color-accent);
  transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.brand-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 28px rgba(15, 76, 129, 0.12);
  border-left-color: var(--color-accent-light);
}

.card-header {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  margin-bottom: 0.75rem;
}

.card-header img {
  opacity: 0.85;
}

.card-number {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--color-accent);
}

.brand-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0 0 0.75rem 0;
  color: var(--color-text);
}

.brand-card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

.figure-block {
  margin: 2rem 0 0 0;
  max-width: 100%;
}

.figure-block img {
  width: 60%;
  max-width: 560px;
  height: auto;
  object-fit: contain;
  border-radius: 10px;
  border: 1px solid var(--color-border);
  display: block;
  transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.figure-block img:hover {
  transform: scale(1.02);
  box-shadow: 0 8px 24px rgba(0,0,0,0.1);
}

.figure-block.figure-compact img {
  max-width: 480px;
}

img[loading="lazy"] {
  content-visibility: auto;
}

.figure-block figcaption {
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: 0.5rem;
}

.product-structure {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.structure-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1rem 1.25rem;
  background: var(--color-bg);
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.structure-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  flex-shrink: 0;
  font-size: 0.8rem;
  padding: 0.25rem 0.6rem;
  background: var(--color-tag-bg);
  color: var(--color-tag);
  border-radius: 4px;
  font-family: var(--font-mono);
}

.structure-tag img {
  opacity: 0.9;
}

.structure-item p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--color-text-muted);
}

.function-index-list {
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

.function-item {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 2rem;
  align-items: center;
}

.function-item-reverse {
  direction: rtl;
}

.function-item-reverse > * {
  direction: ltr;
}

.function-visual {
  max-width: 400px;
}

.function-visual img {
  width: 100%;
  max-width: 380px;
  height: auto;
  object-fit: contain;
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.function-content {
  padding: 0.5rem 0;
}

.function-id {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.function-id img {
  flex-shrink: 0;
}

.function-content h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin: 0 0 0.75rem 0;
  color: var(--color-text);
}

.function-content p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

.function-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.function-card {
  padding: 1.5rem;
  background: var(--color-bg);
  border-radius: 10px;
  border: 1px solid var(--color-border);
  transition: all 0.3s ease;
}

.function-card:hover {
  border-color: var(--color-accent-muted);
  box-shadow: 0 8px 24px rgba(15, 76, 129, 0.1);
  transform: translateY(-3px);
}

.function-card .function-id {
  margin-bottom: 0.5rem;
}

.function-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
  color: var(--color-text);
}

.function-card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.6;
}

.usage-steps {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.usage-step {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
  padding: 1.25rem 1.5rem;
  background: var(--color-bg);
  border-radius: 6px;
  border-left: 4px solid var(--color-accent);
}

.step-num {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  font-size: 0.95rem;
  font-weight: 600;
}

.usage-step h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
  color: var(--color-text);
}

.usage-step p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

.usage-visual {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.usage-visual img {
  width: 60%;
  max-width: 280px;
  height: auto;
  object-fit: contain;
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.security-alert {
  padding: 1.25rem 1.5rem;
  background: var(--color-alert-bg);
  border-left: 4px solid var(--color-alert);
  border-radius: 0 6px 6px 0;
  margin-bottom: 2rem;
}

.alert-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-alert);
  margin-bottom: 0.5rem;
}

.alert-tag img {
  flex-shrink: 0;
}

.security-alert p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--color-text);
  line-height: 1.65;
}

.security-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.security-item {
  padding: 1.25rem 1.5rem;
  background: var(--color-bg-section);
  border: 1px solid var(--color-border);
  border-radius: 6px;
}

.security-item h3 {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
  color: var(--color-text);
}

.security-item h3 img {
  flex-shrink: 0;
  opacity: 0.85;
}

.security-item p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.6;
}

.scenario-list {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.scenario-card {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 2rem;
  align-items: center;
  padding: 1.5rem;
  background: var(--color-bg);
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.scenario-visual {
  max-width: 280px;
}

.scenario-visual img {
  width: 100%;
  max-width: 280px;
  height: auto;
  object-fit: contain;
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.scenario-id {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.scenario-id img {
  flex-shrink: 0;
}

.scenario-body h3,
.scenario-simple-item h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
  color: var(--color-text);
}

.scenario-body p,
.scenario-simple-item p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.6;
}

.scenario-simple {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.scenario-simple-item {
  padding: 1.25rem 1.5rem;
  background: var(--color-bg);
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.terms-table {
  border: 1px solid var(--color-border);
  border-radius: 6px;
  overflow: hidden;
  margin-bottom: 1.5rem;
}

.terms-row {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 1.5rem;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.95rem;
}

.terms-row:last-child {
  border-bottom: none;
}

.terms-row-header {
  background: var(--color-nav);
  color: var(--color-text-on-dark);
  font-weight: 600;
  font-size: 0.9rem;
}

.terms-term {
  font-weight: 500;
  color: var(--color-text);
}

.terms-row span:last-child {
  color: var(--color-text-muted);
  line-height: 1.6;
}

.terms-note {
  padding: 1rem 1.25rem;
  background: var(--color-tag-bg);
  border-radius: 6px;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.terms-note p {
  margin: 0;
  line-height: 1.6;
}

.qa-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.qa-item {
  border: 1px solid var(--color-border);
  border-radius: 6px;
  overflow: hidden;
  background: var(--color-bg-section);
  transition: border-color var(--transition-fast);
}

.qa-item:hover {
  border-color: var(--color-divider);
}

.qa-item.expanded {
  border-color: var(--color-accent-muted);
}

.qa-question {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 1rem 1.25rem;
  background: none;
  border: none;
  text-align: left;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text);
  cursor: pointer;
  transition: background var(--transition-fast);
}

.qa-question:hover {
  background: var(--color-bg);
}

.qa-question::after {
  content: "+";
  margin-left: auto;
  font-size: 1.2rem;
  color: var(--color-text-light);
  transition: transform var(--transition-fast);
}

.qa-item.expanded .qa-question::after {
  transform: rotate(45deg);
}

.qa-icon {
  flex-shrink: 0;
  opacity: 0.75;
}

.qa-num {
  flex-shrink: 0;
  font-size: 0.8rem;
  font-family: var(--font-mono);
  color: var(--color-accent);
}

.qa-answer {
  padding: 0 1.25rem 1rem 3.5rem;
}

.qa-answer[hidden] {
  display: none;
}

.qa-answer p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.7;
}

.qa-answer p strong {
  color: var(--color-text);
}

.archive-section-contact .contact-grid {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.contact-block h3 {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.75rem 0;
  color: var(--color-text);
}

.contact-block h3 img {
  flex-shrink: 0;
  opacity: 0.85;
}

.contact-label {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-tag);
  margin-bottom: 0.25rem;
}

.contact-label img {
  flex-shrink: 0;
  opacity: 0.85;
}

.contact-block p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

.contact-details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.25rem;
}

.contact-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem 1.25rem;
  background: var(--color-bg);
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.contact-item span:last-child {
  font-size: 0.95rem;
  color: var(--color-text);
}

.contact-footer {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-divider);
  text-align: center;
}

.contact-footer p {
  margin: 0.25rem 0;
  font-size: 0.9rem;
  color: var(--color-text-light);
}

.download-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.9rem 1.5rem;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  color: #fff;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: 0 4px 14px rgba(15, 76, 129, 0.35);
}

.btn-download:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(15, 76, 129, 0.45);
}

.btn-download:active {
  transform: translateY(-1px);
}

.btn-ios {
  background: linear-gradient(135deg, #0f6db5 0%, #3a8fd4 100%);
}

.btn-android {
  background: linear-gradient(135deg, #2d7d32 0%, #43a047 100%);
}

.btn-download-icon {
  font-size: 1.25rem;
}

.site-footer {
  margin-top: 4rem;
  padding: 3rem 2rem 2rem;
  background: var(--color-nav);
  color: var(--color-text-on-dark);
  border-radius: 12px 12px 0 0;
}

.footer-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.footer-brand {
  text-align: center;
  margin-bottom: 2rem;
}

.footer-logo {
  width: 128px;
  height: 128px;
  object-fit: contain;
  margin-bottom: 0.5rem;
}

.footer-brand-name {
  margin: 0 0 0.25rem 0;
  font-size: 1.1rem;
  font-weight: 600;
}

.footer-tagline {
  margin: 0;
  font-size: 0.85rem;
  color: var(--color-text-on-dark-muted);
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--color-border-dark);
}

.footer-col h4 {
  margin: 0 0 0.75rem 0;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-on-dark);
}

.footer-col a {
  display: block;
  color: var(--color-text-on-dark-muted);
  text-decoration: none;
  font-size: 0.9rem;
  margin-bottom: 0.4rem;
  transition: color var(--transition-fast);
}

.footer-col a:hover {
  color: var(--color-text-on-dark);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  text-align: center;
}

.footer-justice,
.footer-term {
  color: var(--color-text-on-dark-muted);
  font-size: 0.85rem;
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-justice:hover,
.footer-term:hover {
  color: var(--color-text-on-dark);
}

@media (max-width: 1024px) {
  .function-item {
    grid-template-columns: 1fr;
    direction: ltr;
  }

  .function-item-reverse {
    direction: ltr;
  }

  .function-visual {
    max-width: 100%;
  }

  .scenario-card {
    grid-template-columns: 1fr;
  }

  .scenario-visual {
    max-width: 100%;
  }

  .terms-row {
    grid-template-columns: 1fr;
  }

  .terms-row-header span:first-child {
    display: none;
  }
}

@media (max-width: 768px) {
  :root {
    --content-padding: 1.25rem;
  }

  .figure-block img,
  .usage-visual img,
  .function-visual img,
  .scenario-visual img {
    width: 100%;
    max-width: 100%;
  }

  .nav-sidebar {
    transform: translateX(-100%);
  }

.nav-sidebar.open {
  transform: translateX(0);
}

.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 99;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.nav-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

  .nav-toggle-close {
    display: block;
  }

  .nav-toggle-open {
    display: flex;
  }

  .nav-overlay {
    display: block;
  }

  .nav-logo-img.nav-logo-bitpie {
    width: 80px;
    height: 80px;
  }

  .content-main {
    margin-left: 0;
    padding: 4.5rem 1.25rem 3rem 1.25rem;
    max-width: 100%;
  }

  .archive-entry {
    padding: 2rem 0 2.5rem;
  }

  .archive-entry h1 {
    font-size: 1.6rem;
  }

  .entry-actions {
    flex-direction: column;
  }

  .btn-primary,
  .btn-secondary {
    width: 100%;
    text-align: center;
  }

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

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

  .scenario-simple {
    grid-template-columns: 1fr;
  }

  .usage-step {
    flex-direction: column;
    gap: 1rem;
  }

  .qa-answer {
    padding-left: 1.25rem;
  }
}

.archive-section {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1), transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.archive-section.visible {
  opacity: 1;
  transform: translateY(0);
}

.archive-entry {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1), transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.archive-entry.visible {
  opacity: 1;
  transform: translateY(0);
}

.site-footer {
  opacity: 0;
  transform: translateY(20px);
  animation: footer-fade-in 0.8s ease forwards;
}

@keyframes footer-fade-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}