:root {
  --o4-bg: #000000;
  --o4-bg-alt: #0a0a0a;
  --o4-surface: #111111;
  --o4-border: rgba(255, 255, 255, 0.12);
  --o4-text: #ffffff;
  --o4-muted: #a9a9a9;
  --o4-max: 1140px;
  --o4-radius: 8px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--o4-bg);
  color: var(--o4-text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--o4-text); text-decoration: none; }
a:hover { opacity: 0.85; }
img { max-width: 100%; height: auto; display: block; }

.o4-skip { position: absolute; left: -9999px; }
.o4-skip:focus {
  left: 16px; top: 16px; z-index: 9999;
  padding: 8px 16px; background: #fff; color: #000; border-radius: 4px;
}

.o4-container {
  width: 100%;
  max-width: var(--o4-max);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.o4-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(0, 0, 0, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--o4-border);
}
.o4-header__inner {
  display: flex;
  align-items: center;
  gap: 20px;
  height: 64px;
}
.o4-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 17px;
  color: var(--o4-text);
  white-space: nowrap;
}
.o4-brand:hover { opacity: 1; color: var(--o4-text); }
.o4-brand__logo {
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.05em;
  padding: 4px 8px;
  border: 1px solid var(--o4-border);
  border-radius: 4px;
}

.o4-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
  flex-wrap: wrap;
}
.o4-nav a {
  padding: 8px 12px;
  color: var(--o4-muted);
  font-size: 14px;
  border-radius: 4px;
  transition: color .2s;
}
.o4-nav a:hover { color: var(--o4-text); opacity: 1; }

.o4-nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
  background: none;
  border: 1px solid var(--o4-border);
  border-radius: 4px;
  cursor: pointer;
  margin-left: auto;
}
.o4-nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: #fff;
}

.o4-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  border: 2px solid transparent;
  cursor: pointer;
  transition: opacity .2s, background .2s;
  text-decoration: none;
}
.o4-btn--white {
  background: #fff;
  color: #000;
  border-color: #fff;
}
.o4-btn--white:hover { opacity: 0.9; color: #000; }
.o4-btn--outline {
  background: transparent;
  color: #fff;
  border-color: rgba(255,255,255,.45);
}
.o4-btn--outline:hover { border-color: #fff; opacity: 1; color: #fff; }
.o4-btn--lg { padding: 14px 36px; font-size: 15px; }

/* Hero */
.o4-hero {
  padding: 64px 0 48px;
  border-bottom: 1px solid var(--o4-border);
}
.o4-hero__grid {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 48px;
  align-items: center;
}
.o4-hero__title {
  margin: 0 0 20px;
  font-size: clamp(36px, 5vw, 52px);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}
.o4-hero__lead {
  margin: 0 0 32px;
  font-size: 17px;
  color: var(--o4-muted);
  max-width: 520px;
  line-height: 1.75;
}
.o4-hero__actions { display: flex; flex-wrap: wrap; gap: 12px; }

.o4-phone-mock {
  display: flex;
  justify-content: center;
}
.o4-phone-mock__screen {
  width: 240px;
  height: 480px;
  background: #111;
  border: 2px solid var(--o4-border);
  border-radius: 32px;
  padding: 16px;
  position: relative;
  overflow: hidden;
}
.o4-phone-mock__chart {
  height: 60%;
  margin-top: 40px;
  background: linear-gradient(180deg, rgba(255,255,255,.08) 0%, transparent 100%);
  border-radius: 8px;
  position: relative;
}
.o4-phone-mock__chart::after {
  content: '';
  position: absolute;
  bottom: 20%;
  left: 10%;
  right: 10%;
  height: 2px;
  background: linear-gradient(90deg, transparent, #fff, transparent);
  transform: skewY(-8deg);
}
.o4-phone-mock__label {
  position: absolute;
  bottom: 24px;
  left: 0;
  right: 0;
  text-align: center;
  font-weight: 800;
  font-size: 20px;
  letter-spacing: 0.1em;
}

/* Sections */
.o4-section { padding: 72px 0; }
.o4-section--alt { background: var(--o4-bg-alt); }
.o4-section__intro { text-align: center; max-width: 680px; margin: 0 auto 48px; }
.o4-section__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}
.o4-section__title {
  margin: 0 0 12px;
  font-size: clamp(26px, 3vw, 34px);
  font-weight: 700;
  letter-spacing: -0.02em;
}
.o4-section__desc {
  margin: 0;
  color: var(--o4-muted);
  font-size: 16px;
  line-height: 1.7;
}
.o4-section__more {
  font-size: 14px;
  color: var(--o4-muted);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.o4-section__more:hover { color: #fff; opacity: 1; }

.o4-page-hero {
  padding: 48px 0;
  border-bottom: 1px solid var(--o4-border);
  background: var(--o4-bg-alt);
}
.o4-page-hero__title {
  margin: 0 0 8px;
  font-size: 32px;
  font-weight: 700;
}
.o4-page-hero__desc { margin: 0; color: var(--o4-muted); }

/* Feature grid */
.o4-feature-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.o4-feature {
  padding: 28px 20px;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  background: var(--o4-surface);
}
.o4-feature__icon {
  font-size: 24px;
  margin-bottom: 16px;
  color: var(--o4-muted);
}
.o4-feature__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 700;
}
.o4-feature p {
  margin: 0;
  font-size: 14px;
  color: var(--o4-muted);
  line-height: 1.65;
}

/* Split layout */
.o4-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}
.o4-split--reverse .o4-split__visual { order: -1; }
.o4-split__content .o4-section__title { margin-bottom: 8px; }
.o4-split__content .o4-section__desc { margin-bottom: 28px; }

.o4-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.o4-list li {
  padding: 20px 0;
  border-bottom: 1px solid var(--o4-border);
}
.o4-list li:last-child { border-bottom: none; }
.o4-list__title {
  margin: 0 0 6px;
  font-size: 16px;
  font-weight: 700;
}
.o4-list li p {
  margin: 0;
  font-size: 14px;
  color: var(--o4-muted);
}

.o4-logo-block {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 320px;
  font-size: 72px;
  font-weight: 900;
  letter-spacing: 0.08em;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  background: var(--o4-surface);
  color: var(--o4-muted);
}

.o4-illustration {
  min-height: 320px;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  background: var(--o4-surface);
  position: relative;
  padding: 24px;
}
.o4-illustration__desk {
  width: 80%;
  height: 12px;
  background: var(--o4-border);
  border-radius: 4px;
  margin: 40px auto 0;
}
.o4-illustration__chart {
  width: 60%;
  height: 120px;
  margin: 24px auto;
  border: 1px solid var(--o4-border);
  border-radius: 4px;
}

.o4-shield {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 320px;
  font-size: 80px;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  background: var(--o4-surface);
  opacity: 0.7;
}

/* News cards */
.o4-news-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.o4-news-card {
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  overflow: hidden;
  background: var(--o4-surface);
  transition: border-color .2s;
}
.o4-news-card:hover { border-color: rgba(255,255,255,.35); }
.o4-news-card a { display: block; color: inherit; }
.o4-news-card a:hover { opacity: 1; }
.o4-news-card__media {
  aspect-ratio: 16/10;
  overflow: hidden;
  background: #1a1a1a;
}
.o4-news-card__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.o4-news-card__body { padding: 20px; }
.o4-news-card__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.4;
}
.o4-news-card__desc {
  margin: 0 0 12px;
  font-size: 14px;
  color: var(--o4-muted);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.o4-news-card__link {
  display: inline-block;
  font-size: 13px;
  color: var(--o4-muted);
  margin-bottom: 8px;
}
.o4-news-card__date {
  display: block;
  font-size: 12px;
  color: var(--o4-muted);
}

/* Ticker */
.o4-ticker {
  background: #fff;
  color: #000;
  padding: 12px 0;
}
.o4-ticker__inner {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 14px;
  font-weight: 500;
}
.o4-ticker__icon { font-size: 12px; }

/* List articles */
.o4-list-articles { display: flex; flex-direction: column; gap: 20px; }
.o4-list-articles__item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 20px;
  padding: 20px;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  background: var(--o4-surface);
}
.o4-list-articles__media {
  aspect-ratio: 16/10;
  overflow: hidden;
  border-radius: 4px;
  background: #1a1a1a;
}
.o4-list-articles__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.o4-list-articles__body {
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.o4-list-articles__title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 700;
}
.o4-list-articles__title a { color: inherit; }
.o4-list-articles__title a:hover { text-decoration: underline; opacity: 1; }
.o4-list-articles__meta {
  font-size: 13px;
  color: var(--o4-muted);
  display: flex;
  gap: 16px;
  margin-bottom: 8px;
}
.o4-list-articles__desc {
  margin: 0;
  font-size: 14px;
  color: var(--o4-muted);
  line-height: 1.6;
}

/* CTA */
.o4-cta {
  padding: 80px 0;
  text-align: center;
  border-top: 1px solid var(--o4-border);
  border-bottom: 1px solid var(--o4-border);
}
.o4-cta__title {
  margin: 0 0 12px;
  font-size: 32px;
  font-weight: 700;
}
.o4-cta__desc {
  margin: 0 0 28px;
  color: var(--o4-muted);
  font-size: 16px;
}
.o4-cta__stores {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}
.o4-store-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 140px;
  padding: 14px 28px;
  border: 1px solid var(--o4-border);
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  color: #fff;
  transition: background .2s, border-color .2s;
}
.o4-store-btn:hover {
  background: #fff;
  color: #000;
  border-color: #fff;
  opacity: 1;
}

/* FAQ */
.o4-faq-wrap { max-width: 760px; margin: 0 auto; }
.o4-faq-wrap .o4-section__title { text-align: center; }
.o4-faq-wrap .o4-section__desc { text-align: center; margin-bottom: 32px; }
.o4-faq { border-top: 1px solid var(--o4-border); }
.o4-faq__item {
  border-bottom: 1px solid var(--o4-border);
}
.o4-faq__item summary {
  padding: 20px 0;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.o4-faq__item summary::-webkit-details-marker { display: none; }
.o4-faq__item summary::after {
  content: '+';
  font-size: 20px;
  color: var(--o4-muted);
  font-weight: 400;
}
.o4-faq__item[open] summary::after { content: '−'; }
.o4-faq__item p {
  margin: 0 0 20px;
  padding-right: 24px;
  font-size: 14px;
  color: var(--o4-muted);
  line-height: 1.7;
}

.o4-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
}
.o4-links a { color: var(--o4-muted); font-size: 14px; }

/* Article */
.o4-breadcrumb {
  font-size: 14px;
  color: var(--o4-muted);
  margin-bottom: 24px;
}
.o4-breadcrumb a { color: var(--o4-muted); }

.o4-article {
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  padding: 36px;
  background: var(--o4-surface);
}
.o4-article__title {
  margin: 0 0 12px;
  font-size: 30px;
  font-weight: 700;
  line-height: 1.35;
}
.o4-article__meta {
  color: var(--o4-muted);
  font-size: 14px;
  display: flex;
  gap: 16px;
  margin-bottom: 16px;
}
.o4-article__intro {
  padding: 16px 0;
  border-top: 1px solid var(--o4-border);
  border-bottom: 1px solid var(--o4-border);
  color: var(--o4-muted);
  margin-bottom: 24px;
}
.o4-article__content {
  font-size: 16px;
  line-height: 1.85;
  color: #d4d4d4;
}
.o4-article__content h2,
.o4-article__content h3 {
  color: #fff;
  margin-top: 28px;
  margin-bottom: 12px;
}
.o4-article__content p { margin: 0 0 16px; }
.o4-article__content img { border-radius: 4px; }
.o4-article__source {
  margin-top: 24px;
  font-size: 13px;
  color: var(--o4-muted);
}

.o4-prevnext {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 28px;
}
.o4-prevnext a {
  display: block;
  padding: 16px;
  border: 1px solid var(--o4-border);
  border-radius: var(--o4-radius);
  color: #fff;
}
.o4-prevnext a:hover { border-color: rgba(255,255,255,.4); opacity: 1; }
.o4-prevnext span {
  display: block;
  font-size: 12px;
  color: var(--o4-muted);
  margin-bottom: 4px;
}

.o4-pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 32px;
  flex-wrap: wrap;
}
.o4-pagination a,
.o4-pagination span {
  padding: 8px 14px;
  border: 1px solid var(--o4-border);
  border-radius: 4px;
  font-size: 14px;
  color: #fff;
}
.o4-pagination a:hover {
  background: #fff;
  color: #000;
  opacity: 1;
}
.o4-pagination .current {
  background: #fff;
  color: #000;
}

.o4-empty {
  text-align: center;
  padding: 60px 20px;
  color: var(--o4-muted);
}
.o4-empty__title {
  font-size: 72px;
  margin: 0 0 12px;
  font-weight: 700;
  color: #fff;
}

/* Footer */
.o4-footer {
  border-top: 1px solid var(--o4-border);
  padding: 56px 0 32px;
  background: var(--o4-bg-alt);
}
.o4-footer__grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(3, 1fr);
  gap: 32px;
  margin-bottom: 40px;
}
.o4-footer__brand {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 12px;
}
.o4-footer__desc {
  font-size: 14px;
  color: var(--o4-muted);
  line-height: 1.65;
  margin: 0;
}
.o4-footer__title {
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
  color: var(--o4-muted);
}
.o4-footer__col a {
  display: block;
  font-size: 14px;
  color: var(--o4-muted);
  margin-bottom: 10px;
}
.o4-footer__col a:hover { color: #fff; opacity: 1; }
.o4-footer__bottom {
  text-align: center;
  padding-top: 24px;
  border-top: 1px solid var(--o4-border);
  font-size: 13px;
  color: var(--o4-muted);
}
.o4-footer__bottom a { color: var(--o4-muted); }
.o4-footer__meta { margin-top: 8px; font-size: 12px; }

/* Responsive */
@media (max-width: 1024px) {
  .o4-feature-grid,
  .o4-news-grid { grid-template-columns: repeat(2, 1fr); }
  .o4-split { grid-template-columns: 1fr; }
  .o4-split--reverse .o4-split__visual { order: 0; }
  .o4-footer__grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .o4-nav-toggle { display: flex; }
  .o4-nav {
    display: none;
    flex-direction: column;
    width: 100%;
    order: 5;
    padding: 12px 0;
    border-top: 1px solid var(--o4-border);
  }
  .o4-nav.is-open { display: flex; }
  .o4-header__inner { flex-wrap: wrap; height: auto; padding: 12px 0; }
  .o4-hero__grid { grid-template-columns: 1fr; }
  .o4-hero { padding: 40px 0; }
  .o4-section { padding: 48px 0; }
  .o4-feature-grid,
  .o4-news-grid { grid-template-columns: 1fr; }
  .o4-list-articles__item { grid-template-columns: 1fr; }
  .o4-prevnext { grid-template-columns: 1fr; }
  .o4-footer__grid { grid-template-columns: 1fr; }
  .o4-article { padding: 20px; }
  .o4-article__title { font-size: 24px; }
  .o4-phone-mock__screen { width: 200px; height: 400px; }
}