:root {
  --accent: #dc2222;
  --accent-dark: #991b1b;
  --accent-soft: #fff1f1;
  --paper: #fffdf8;
  --paper-deep: #f7f1e8;
  --ink: #1f2937;
  --muted: #6b7280;
  --line: #e8dfd2;
  --shadow: 0 18px 50px rgba(31, 41, 55, 0.08);
  --radius: 18px;
  --max: 1120px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top right, rgba(220, 34, 34, 0.06), transparent 28%),
    linear-gradient(180deg, var(--paper) 0%, #ffffff 40%, var(--paper-deep) 100%);
  line-height: 1.7;
}

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

button {
  font: inherit;
  color: inherit;
}

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

.container {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 0.92rem;
  letter-spacing: 0.18em;
}

.section {
  padding: 88px 0;
}

.section-alt {
  background: rgba(255, 255, 255, 0.72);
  border-block: 1px solid var(--line);
}

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 48px;
}

.section-head.align-left {
  text-align: left;
  margin-left: 0;
}

.section-head h2 {
  margin: 0 0 12px;
  font-size: clamp(1.8rem, 3vw, 2.5rem);
  line-height: 1.25;
}

.section-head p:last-child {
  margin: 0;
  color: var(--muted);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(14px);
  background: rgba(255, 253, 248, 0.88);
  border-bottom: 1px solid rgba(232, 223, 210, 0.9);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  gap: 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-mark {
  border-radius: 10px;
  box-shadow: 0 8px 20px rgba(220, 34, 34, 0.18);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-text strong {
  font-size: 1.05rem;
}

.brand-text small {
  color: var(--muted);
  font-size: 0.82rem;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 0.95rem;
}

.site-nav a,
.site-nav .nav-cta-btn {
  color: var(--muted);
  transition: color 0.2s ease;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--accent);
}

.nav-cta,
.nav-cta-btn {
  padding: 10px 18px;
  border-radius: 999px;
  background: var(--accent);
  color: #fff !important;
  font-weight: 600;
  border: 0;
  cursor: pointer;
}

.nav-cta-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  border-radius: 12px;
  background: var(--accent-soft);
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  margin: 4px auto;
  background: var(--accent);
}

.hero {
  padding: 72px 0 88px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 40px;
  align-items: center;
}

.hero-copy h1 {
  margin: 0 0 18px;
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  line-height: 1.15;
  letter-spacing: 0.02em;
}

.hero-copy h1 em {
  color: var(--accent);
  font-style: normal;
}

.lead {
  margin: 0 0 28px;
  max-width: 640px;
  color: var(--muted);
  font-size: 1.05rem;
}

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

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 22px;
  border-radius: 999px;
  font-weight: 600;
  border: 0;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

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

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  color: #fff;
  box-shadow: 0 12px 28px rgba(220, 34, 34, 0.24);
}

.btn-ghost {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.8);
}

.btn-lg {
  min-height: 54px;
  padding: 0 28px;
}

.hero-panel {
  position: relative;
  min-height: 360px;
  padding: 32px;
  border-radius: 28px;
  background:
    linear-gradient(145deg, rgba(255, 255, 255, 0.95), rgba(255, 241, 241, 0.9)),
    url("data:image/svg+xml,%3Csvg width='120' height='120' viewBox='0 0 120 120' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M60 0l60 60-60 60L0 60z' fill='%23dc2222' fill-opacity='0.03'/%3E%3C/svg%3E");
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.seal {
  position: absolute;
  top: 28px;
  right: 28px;
  width: 88px;
  height: 88px;
  display: grid;
  place-items: center;
  border: 3px solid var(--accent);
  border-radius: 14px;
  color: var(--accent);
  font-size: 2.6rem;
  font-weight: 800;
  transform: rotate(8deg);
}

.hero-tags {
  list-style: none;
  margin: 120px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.hero-tags li {
  padding: 14px 18px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.86);
  border: 1px solid var(--line);
  font-weight: 600;
}

.card-grid {
  display: grid;
  gap: 22px;
}

.card-grid.features {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.card-grid.charts {
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
}

.topic-card,
.about-card,
.chart-chip,
.download-panel {
  padding: 24px;
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.topic-icon {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  margin-bottom: 16px;
  border-radius: 12px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 1.15rem;
  font-weight: 800;
}

.topic-card h3,
.about-card h3,
.download-main h3 {
  margin: 0 0 10px;
}

.topic-card p,
.about-grid p,
.ai-grid > div > p {
  margin: 0;
  color: var(--muted);
}

.chart-chip {
  display: grid;
  gap: 6px;
  align-content: start;
  min-height: 120px;
}

.chart-chip span {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 800;
}

.chart-chip strong {
  font-size: 1rem;
}

.chart-chip small {
  color: var(--muted);
}

.ai-grid,
.about-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 28px;
  align-items: start;
}

.ai-points {
  margin: 22px 0 28px;
  padding-left: 1.2em;
  color: var(--muted);
}

.ai-points li + li {
  margin-top: 8px;
}

.ai-card,
.about-card dl {
  margin: 0;
}

.about-card dl div + div {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.about-card dt {
  margin-bottom: 4px;
  color: var(--muted);
  font-size: 0.88rem;
}

.about-card dd {
  margin: 0;
}

.about-card a {
  color: var(--accent);
}

.download-panel {
  max-width: 820px;
  margin: 0 auto;
  display: grid;
  gap: 22px;
}

.download-main {
  display: flex;
  align-items: center;
  gap: 18px;
}

.download-icon {
  border-radius: 16px;
  box-shadow: 0 10px 24px rgba(220, 34, 34, 0.18);
}

.download-meta,
.download-tip {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.download-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.cta-band {
  padding: 0;
}

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 42px;
  border-radius: 28px;
  background: linear-gradient(135deg, #1f2937, #374151);
  color: #fff;
  box-shadow: var(--shadow);
}

.cta-inner p {
  margin: 10px 0 0;
  color: rgba(255, 255, 255, 0.78);
}

.site-footer {
  padding: 36px 0 48px;
  border-top: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.7);
}

.footer-inner {
  display: grid;
  gap: 18px;
}

.footer-brand p,
.footer-copy {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  color: var(--muted);
}

.wechat-mask {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: grid;
  place-items: start end;
  padding: 18px 18px 40px;
  background: rgba(15, 23, 42, 0.72);
}

.wechat-mask[hidden] {
  display: none;
}

.wechat-mask-panel {
  width: min(360px, 100%);
  margin-top: 8px;
  padding: 28px 24px;
  border-radius: 20px;
  background: #fff;
  box-shadow: var(--shadow);
  text-align: left;
}

.wechat-arrow {
  margin: 0 0 8px;
  text-align: right;
  font-size: 2rem;
  color: var(--accent);
  line-height: 1;
}

.wechat-mask-panel h2 {
  margin: 0 0 10px;
  font-size: 1.25rem;
}

.wechat-mask-panel p {
  margin: 0 0 20px;
  color: var(--muted);
}

@media (max-width: 900px) {
  .hero-grid,
  .about-grid,
  .ai-grid {
    grid-template-columns: 1fr;
  }

  .hero-panel {
    min-height: 280px;
  }

  .cta-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 760px) {
  .section {
    padding: 64px 0;
  }

  .nav-toggle {
    display: block;
  }

  .site-nav {
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 16px 20px 24px;
    background: rgba(255, 253, 248, 0.98);
    border-bottom: 1px solid var(--line);
  }

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

  .site-nav a,
  .site-nav .nav-cta-btn {
    padding: 10px 0;
  }

  .nav-cta,
  .nav-cta-btn {
    text-align: center;
    width: 100%;
  }
}