:root {
  color-scheme: light;
  --ink: #202a3a;
  --muted: #5e6a7d;
  --line: #e1e7ef;
  --surface: #ffffff;
  --page: #f4f7fb;
  --shadow: 0 18px 42px rgba(31, 50, 74, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 50% 0, #fff 0, transparent 38rem),
    var(--page);
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

main {
  width: min(1440px, calc(100% - 48px));
  margin: 0 auto;
  padding: 72px 0 80px;
}

.hero {
  margin-bottom: 48px;
  text-align: center;
}

.eyebrow {
  margin: 0 0 12px;
  color: #2377d1;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.15em;
}

h1 {
  margin: 0;
  font-size: clamp(42px, 5.2vw, 76px);
  font-weight: 800;
  letter-spacing: -0.045em;
  line-height: 1.05;
}

.subtitle {
  margin: 22px 0 0;
  color: var(--muted);
  font-size: clamp(17px, 1.8vw, 23px);
}

.downloads,
.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 30px;
}

.download-card,
.step-card {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 30px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.download-card {
  display: flex;
  min-width: 0;
  flex-direction: column;
}

.product-image {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  max-height: none;
  aspect-ratio: auto;
  object-fit: contain;
  object-position: center;
  background: #edf2f7;
}

.card-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  padding: 30px;
}

.card-body h2 {
  margin: 0 0 18px;
  font-size: clamp(24px, 2vw, 31px);
  font-weight: 800;
}

.card-body p {
  flex: 1;
  margin: 0 0 26px;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.75;
}

code {
  padding: 0.12em 0.38em;
  border-radius: 6px;
  background: #edf1f6;
  font-family: Consolas, monospace;
  font-size: 0.88em;
}

.download-button {
  display: flex;
  min-height: 58px;
  align-items: center;
  justify-content: center;
  padding: 14px 20px;
  border-radius: 16px;
  color: #fff;
  font-size: 18px;
  font-weight: 800;
  text-align: center;
  text-decoration: none;
  transition: transform 160ms ease, filter 160ms ease;
}

.download-button:hover {
  filter: brightness(1.06);
  transform: translateY(-2px);
}

.download-button:focus-visible,
#close-tip:focus-visible {
  outline: 3px solid #ffc544;
  outline-offset: 3px;
}

.button-pc {
  background: linear-gradient(135deg, #2582ee, #205fbd);
}

.button-android {
  background: linear-gradient(135deg, #19a45d, #13864b);
}

.button-ios {
  background: linear-gradient(135deg, #18a9cf, #117da7);
}

.install-guide {
  margin-top: 72px;
  scroll-margin-top: 24px;
}

.guide-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 26px;
}

.guide-heading h2 {
  margin: 0 0 10px;
  font-size: clamp(30px, 3vw, 42px);
  font-weight: 800;
}

.guide-heading p {
  margin: 0;
  color: var(--muted);
  font-size: 18px;
}

.guide-heading span {
  flex: 0 0 auto;
  padding: 12px 18px;
  border: 1px solid #bfdaef;
  border-radius: 999px;
  color: #176a9b;
  background: rgba(255, 255, 255, 0.7);
}

.step-card {
  border-radius: 26px;
}

/* 安装步骤图必须完整显示：不设固定高度、不裁剪、不放大到超出容器。 */
.step-image {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  max-height: none;
  object-fit: contain;
  object-position: center;
  background: #fff;
}

.step-copy {
  padding: 24px 26px 28px;
}

.step-copy h3 {
  margin: 0 0 10px;
  font-size: 21px;
  font-weight: 800;
}

.step-copy p {
  margin: 0;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.65;
}

.is-hidden {
  display: none !important;
}

.wechat-tip {
  position: fixed;
  z-index: 100;
  inset: 0;
  padding: 86px 34px 34px;
  color: #fff;
  background: rgba(13, 23, 38, 0.94);
  text-align: center;
}

.wechat-tip h2 {
  margin: 48px 0 16px;
  font-size: 30px;
}

.wechat-tip p {
  max-width: 520px;
  margin: 0 auto;
  font-size: 18px;
  line-height: 1.8;
}

.tip-arrow {
  position: absolute;
  top: 18px;
  right: 28px;
  font-size: 58px;
}

#close-tip {
  position: absolute;
  top: 20px;
  left: 22px;
  width: 44px;
  height: 44px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 50%;
  color: #fff;
  background: transparent;
  font-size: 30px;
  cursor: pointer;
}

@media (max-width: 980px) {
  main {
    width: min(720px, calc(100% - 32px));
    padding-top: 50px;
  }

  .downloads,
  .steps {
    grid-template-columns: 1fr;
  }

  .download-card,
  .step-card {
    border-radius: 24px;
  }

  .guide-heading {
    align-items: flex-start;
    flex-direction: column;
  }

  /* 手机端仍按图片原始比例缩放，每张图从上到下完整可见。 */
  .step-image {
    width: auto !important;
    height: auto !important;
    max-width: 100% !important;
    max-height: none !important;
    margin: 0 auto;
    object-fit: contain !important;
    object-position: center !important;
  }
}

@media (max-width: 520px) {
  main {
    width: calc(100% - 24px);
    padding: 34px 0 52px;
  }

  .hero {
    margin-bottom: 30px;
  }

  h1 {
    font-size: 42px;
  }

  .subtitle {
    margin-top: 16px;
    font-size: 16px;
    line-height: 1.6;
  }

  .downloads,
  .steps {
    gap: 20px;
  }

  .card-body {
    padding: 22px 20px 20px;
  }

  .card-body h2 {
    margin-bottom: 12px;
    font-size: 25px;
  }

  .card-body p {
    margin-bottom: 20px;
    font-size: 16px;
  }

  .install-guide {
    margin-top: 50px;
  }

  .guide-heading p,
  .guide-heading span {
    font-size: 15px;
  }

  .step-copy {
    padding: 20px;
  }
}