:root {
  --dark: #05090e;
  --charcoal: #0c1218;
  --panel: #111a22;
  --text: #f4f7f8;
  --muted: rgba(244, 247, 248, 0.68);
  --muted-strong: rgba(244, 247, 248, 0.82);
  --line: rgba(255, 255, 255, 0.16);
  --page-light: #eef3f6;
  --surface-light: #ffffff;
  --surface-soft: #f7fafb;
  --text-dark: #12212c;
  --muted-dark: #60717c;
  --line-light: #d5e0e6;
  --accent: #dfe8eb;
  --accent-dark: #0d171f;
  --max-width: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background: var(--page-light);
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Segoe UI", Arial, sans-serif;
  line-height: 1.62;
  letter-spacing: 0;
}

a {
  color: inherit;
  text-decoration: none;
}

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

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 30;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 22px;
  min-height: 72px;
  padding: 0 clamp(18px, 4vw, 54px);
  color: rgba(255, 255, 255, 0.86);
  background: linear-gradient(180deg, rgba(5, 9, 14, 0.72), rgba(5, 9, 14, 0));
}

.site-brand {
  justify-self: start;
  font-weight: 850;
  letter-spacing: 0.08em;
}

.site-brand span {
  margin-left: 8px;
  color: rgba(255, 255, 255, 0.62);
  font-weight: 650;
  letter-spacing: 0;
}

.site-nav {
  display: flex;
  gap: 30px;
  justify-self: center;
  font-size: 0.96rem;
}

.lang-switch {
  display: inline-flex;
  gap: 8px;
  justify-self: end;
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.9rem;
}

.site-nav a,
.lang-switch a {
  color: rgba(255, 255, 255, 0.76);
}

.site-nav a:hover,
.site-nav a:focus-visible,
.lang-switch a:hover,
.lang-switch a:focus-visible,
.lang-switch .is-active {
  color: #ffffff;
}

.hero {
  position: relative;
  min-height: 100vh;
  display: grid;
  align-items: center;
  overflow: hidden;
}

.hero__image,
.hero__shade {
  position: absolute;
  inset: 0;
}

.hero__image {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero__shade {
  background:
    linear-gradient(90deg, rgba(5, 9, 14, 0.88) 0%, rgba(5, 9, 14, 0.54) 40%, rgba(5, 9, 14, 0.18) 75%),
    linear-gradient(180deg, rgba(5, 9, 14, 0.38) 0%, rgba(5, 9, 14, 0.08) 48%, rgba(5, 9, 14, 0.72) 100%);
}

.hero__content {
  position: relative;
  z-index: 1;
  width: min(calc(100% - 36px), var(--max-width));
  margin: 0 auto;
  padding-top: 80px;
}

.eyebrow {
  margin: 0 0 12px;
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.84rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.hero h1 {
  max-width: 720px;
  margin: 0;
  color: #ffffff;
  font-size: 4.2rem;
  line-height: 1.08;
}

.hero p {
  max-width: 620px;
  margin: 18px 0 0;
  color: var(--muted-strong);
  font-size: 1.12rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 150px;
  min-height: 44px;
  padding: 0 22px;
  border-radius: 4px;
  font-weight: 800;
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.button--primary {
  background: rgba(244, 247, 248, 0.92);
  color: var(--accent-dark);
}

.button--primary:hover,
.button--primary:focus-visible {
  background: #ffffff;
}

.button--ghost {
  border: 1px solid rgba(255, 255, 255, 0.48);
  color: #ffffff;
  background: rgba(255, 255, 255, 0.08);
}

.button--ghost:hover,
.button--ghost:focus-visible {
  background: rgba(255, 255, 255, 0.16);
}

.showcase,
.topics,
.about {
  width: min(calc(100% - 36px), var(--max-width));
  margin: 0 auto;
}

.showcase {
  padding: 88px 0 96px;
}

.section-head {
  margin-bottom: 28px;
}

.section-head h2 {
  margin: 0;
  color: var(--text-dark);
  font-size: 2.15rem;
  line-height: 1.24;
}

.slider {
  position: relative;
  min-height: 660px;
  overflow: hidden;
  border-radius: 6px;
  background: var(--surface-light);
  box-shadow: 0 22px 54px rgba(30, 48, 60, 0.12);
}

.slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 0.75s ease;
  pointer-events: none;
}

.slide.is-active {
  opacity: 1;
  pointer-events: auto;
}

.slide img,
.slide__shade {
  position: absolute;
  inset: 0;
}

.slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.slide__shade {
  background:
    linear-gradient(90deg, rgba(5, 9, 14, 0.86) 0%, rgba(5, 9, 14, 0.52) 42%, rgba(5, 9, 14, 0.18) 78%),
    linear-gradient(180deg, rgba(5, 9, 14, 0.2), rgba(5, 9, 14, 0.62));
}

.slide__copy {
  position: absolute;
  left: clamp(28px, 6vw, 72px);
  bottom: clamp(34px, 7vw, 76px);
  z-index: 1;
  max-width: 560px;
}

.slide__copy span {
  color: rgba(255, 255, 255, 0.64);
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.06em;
}

.slide__copy h3 {
  margin: 12px 0 12px;
  color: #ffffff;
  font-size: 2.65rem;
  line-height: 1.14;
}

.slide__copy p {
  max-width: 520px;
  margin: 0 0 28px;
  color: var(--muted-strong);
}

.slider__controls {
  position: absolute;
  right: clamp(24px, 4vw, 54px);
  bottom: clamp(24px, 4vw, 44px);
  z-index: 2;
  display: flex;
  gap: 10px;
}

.slider__controls button {
  width: 44px;
  height: 3px;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.34);
  cursor: pointer;
}

.slider__controls button.is-active {
  background: #ffffff;
}

.topics {
  padding: 24px 0 96px;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.topic-card {
  overflow: hidden;
  border-radius: 6px;
  border: 1px solid var(--line-light);
  background: var(--surface-light);
  box-shadow: 0 14px 34px rgba(30, 48, 60, 0.08);
}

.topic-card img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  opacity: 0.88;
}

.topic-card div {
  padding: 20px 20px 24px;
}

.topic-card h3 {
  margin: 0 0 10px;
  color: var(--text-dark);
  font-size: 1.18rem;
  line-height: 1.42;
}

.topic-card p {
  margin: 0;
  color: var(--muted-dark);
  font-size: 0.95rem;
}

.about {
  padding: 32px 0 80px;
  color: var(--muted-dark);
  text-align: center;
}

.about p {
  margin: 0 auto;
  max-width: 780px;
}

.site-footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 18px 26px;
  padding: 28px 18px 36px;
  color: var(--muted-dark);
  border-top: 1px solid var(--line-light);
  background: var(--surface-soft);
  font-size: 0.92rem;
}

.footer-action {
  padding: 0;
  border: 0;
  color: inherit;
  background: transparent;
  font: inherit;
  cursor: pointer;
}

.footer-action:hover,
.footer-action:focus-visible,
.site-footer a:hover,
.site-footer a:focus-visible {
  color: var(--text-dark);
}

.modal-open {
  overflow: hidden;
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 40;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(5, 9, 14, 0.72);
}

.modal-backdrop.is-open {
  display: flex;
}

.modal-dialog {
  position: relative;
  width: min(100%, 520px);
  max-height: calc(100vh - 48px);
  overflow: auto;
  padding: 28px 24px 24px;
  border-radius: 8px;
  background: #ffffff;
  box-shadow: 0 24px 60px rgba(5, 9, 14, 0.28);
  text-align: center;
}

.modal-dialog h2 {
  margin: 0 32px 10px;
  color: var(--text-dark);
  font-size: 1.35rem;
  line-height: 1.35;
}

.modal-helper {
  margin: 0 0 18px;
  color: var(--text-dark);
  font-size: 0.98rem;
}

.modal-note {
  margin: 14px 0 0;
  color: var(--muted-dark);
  font-size: 0.9rem;
}

.modal-qr {
  width: min(100%, 380px);
  height: auto;
  margin: 0 auto;
  border-radius: 6px;
}

.modal-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: 999px;
  color: var(--muted-dark);
  background: #eef3f6;
  font-size: 1.25rem;
  line-height: 1;
  cursor: pointer;
}

.modal-close:hover,
.modal-close:focus-visible {
  color: var(--text-dark);
}

@media (max-width: 900px) {
  .site-header {
    grid-template-columns: 1fr;
    gap: 10px;
    align-items: start;
    padding-top: 16px;
    padding-bottom: 16px;
    background: rgba(5, 9, 14, 0.76);
  }

  .site-nav,
  .lang-switch {
    justify-self: start;
  }

  .hero h1 {
    font-size: 3rem;
  }

  .slider {
    min-height: 560px;
  }

  .slide__copy h3 {
    font-size: 2.1rem;
  }

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

@media (max-width: 560px) {
  .hero {
    min-height: 780px;
  }

  .hero h1 {
    font-size: 2.35rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .hero__actions,
  .slide__copy .button {
    width: 100%;
  }

  .button {
    width: 100%;
  }

  .showcase {
    padding-top: 64px;
  }

  .section-head h2 {
    font-size: 1.55rem;
  }

  .slider {
    min-height: 620px;
  }

  .slide__copy {
    right: 24px;
  }

  .slider__controls {
    left: 24px;
    right: auto;
  }

  .modal-backdrop {
    padding: 16px;
  }

  .modal-dialog {
    padding: 24px 18px 18px;
  }
}