:root {
  --bg-sky: #c8eef1;
  --ink: #1a1a1a;
  --ink-soft: #5c5c5c;
  --accent-pink: #f458b7;
  --accent-teal: #2adfde;
  --bar: #18191b;
  --bar-sub: #F1F3F6;
  --btn: #000000;
  --white: #ffffff;
  --font: "PingFang SC", "Hiragino Sans GB", "Source Han Sans SC",
    "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  min-height: 100%;
}

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg-sky);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ========== Desktop ========== */
.desktop {
  display: none;
}

@media (min-width: 961px) {
  .desktop {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
    width: 100%;
    background: var(--bg-sky);
    position: relative;
    /* 允许页面在高度不够或过长时滚动，防止内容截断或变形 */
    overflow-y: auto;
    overflow-x: hidden;
  }

  /* 1. 背景画框：锁定 16:9 标准比例（1920x1080 基准），不使用 cover 强制拉伸 */
  .desktop__frame {
    position: relative;
    left: auto;
    top: auto;
    transform: none;

    /* 核心：宽度100%，高度自动按 16:9 等比计算，确保 bg.png 绝对不变形 */
    width: 100vw;
    height: calc(100vw * 9 / 16);
    min-height: 100vh; /* 保证至少撑满一屏 */

    flex-shrink: 0;
    container-type: inline-size;
    container-name: stage;
  }

  /* 2. 背景图片完整展示，保持比例 */
  .desktop__art {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover; /* 保证画面铺满 16:9 画框 */
    user-select: none;
    pointer-events: none;
  }

  /* 3. 底部备案栏：位于画框下方，当页面高度超出时可滚动到底部查看 */
  .foot {
    position: relative;
    bottom: auto;
    left: auto;
    z-index: 10;

    width: 100%;
    height: 52px;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    padding: 6px 20px;
    background: rgba(29, 29, 29, 1);
    color: rgba(255, 255, 255, 0.72);
    font-size: 11px;
    font-weight: 500;
  }

  .foot a {
    color: rgba(255, 255, 255, 0.72);
  }

  .foot a:hover {
    color: #fff;
  }
  /* 顶部条相对视口全宽 */
  .desktop__topbar {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 4;
    height: clamp(56px, 3.9vw, 75px);
    padding: 0 clamp(20px, 3.4vw, 48px);
    display: flex;
    align-items: center;
    background: rgba(0, 0, 0, 0.2);
  }

  .desktop__logo {
    display: inline-flex;
    align-items: center;
    gap: 10px;
  }

  .desktop__logo img {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    object-fit: cover;
    background: #fff;
  }

  .desktop__logo span {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: 0.04em;
    color: var(--ink);
    line-height: 1;
  }

  /*
   * 设计稿标注（1920×1080）：
   * left 141 · gap 22 · 扫码 255×113.33 · 商店 238×114.75 · 距底 269.67
   */
  .desktop__download {
    position: absolute;
    left: 7.34375%; /* 141 / 1920 */
    bottom: 24.969%; /* 269.67 / 1080 */
    top: auto;
    z-index: 3;
  }

  .desktop__frame .download-row {
    gap: 1.145833cqi; /* 22 / 1920 */
  }

  .desktop__frame .dl-card {
    border-radius: 0.9375cqi; /* 18 / 1920 */
  }

  /* 扫码按钮 255×113.33 */
  .desktop__frame .dl-card--qr {
    width: 13.28125cqi;
    height: 5.9026cqi;
    padding: 0 1.25cqi 0 1.041667cqi; /* 24 / 20 */
    gap: 0.833333cqi; /* 16 */
  }

  .desktop__frame .dl-card__qr {
    width: 3.854167cqi; /* 74 */
    height: 3.854167cqi;
    padding: 0.260417cqi; /* 5 */
    border-radius: 0.416667cqi; /* 8 */
  }

  /* 商店按钮 238×114.75 */
  .desktop__frame .dl-card--store {
    width: 12.395833cqi; /* 238 / 1920 */
    height: 5.9765625cqi; /* 114.75 / 1920 */
    padding: 0 1.458333cqi 0 1.354167cqi; /* 28 / 26 */
    gap: 0.833333cqi; /* 16 */
  }

  .desktop__frame .dl-card__icon {
    width: 2.8125cqi; /* 54 */
    height: 2.8125cqi;
  }

  .desktop__frame .dl-card__text {
    gap: 0.4cqi; /* 3 */
  }

  .desktop__frame .dl-card--qr .dl-card__line--sm {
    font-size: 1cqi; /* 16 */
    font-weight: 700;
  }

  .desktop__frame .dl-card--qr .dl-card__line--lg {
    font-size: 1.041667cqi; /* 20 */
    font-weight: 700;
  }

  .desktop__frame .dl-card--store .dl-card__line--lg {
    font-size: 1.145833cqi; /* 22 */
    font-weight: 700;
    line-height: 1.15;
  }

  .desktop__frame .dl-card--store .dl-card__line--sm {
    font-size: 0.9375cqi; /* 18，约 Android 的 80% */
    font-weight: 600;
    line-height: 1.15;
  }

  .mobile {
    display: none !important;
  }
}

/* ========== 下载卡片 ========== */
.download-row {
  display: flex;
  align-items: center;
  gap: 22px;
}

.dl-card {
  display: inline-flex;
  flex-direction: row;
  align-items: center;
  justify-content: flex-start;
  border-radius: 18px;
  background: #000;
  color: #fff;
  box-sizing: border-box;
  flex-shrink: 0;
  transition: transform 0.18s ease, background 0.18s ease;
}

/* 扫码：255×113.33 */
.dl-card--qr {
  width: 255px;
  height: 113.33px;
  padding: 0 24px 0 20px;
  gap: 16px;
}

/* 商店：238×114.75 */
.dl-card--store {
  width: 238px;
  height: 114.75px;
  padding: 0 28px 0 26px;
  gap: 16px;
}

a.dl-card:hover {
  background: #111;
  transform: translateY(-1px);
}

a.dl-card:active {
  transform: translateY(0);
}

.dl-card__media {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.dl-card__qr {
  width: 74px;
  height: 74px;
  padding: 5px;
  background: #fff;
  border-radius: 8px;
  overflow: hidden;
  box-sizing: border-box;
}

.dl-card__qr img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.dl-card__icon {
  width: 60px;
  height: 60px;
  object-fit: contain;
}

.dl-card__text {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  min-width: 0;
}

.dl-card__line {
  white-space: nowrap;
  color: #fff;
}

/* 扫码：文案居中对齐 */
.dl-card--qr .dl-card__text {
  align-items: center;
  text-align: center;
}

.dl-card--qr .dl-card__line--sm {
  font-size: 16px;
  font-weight: 500;
  letter-spacing: 0.02em;
  line-height: 1.2;
}

.dl-card--qr .dl-card__line--lg {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.01em;
  line-height: 1.15;
}

/* 商店：「下载」与平台名左对齐 */
.dl-card--store .dl-card__text {
  align-items: flex-start;
  text-align: left;
}

.dl-card--store .dl-card__line--lg {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.01em;
  line-height: 1.15;
}

.dl-card--store .dl-card__line--sm {
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.15;
}

/* ========== Mobile / tablet ========== */
.mobile {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-sky);
  background-image: url("../assets/bg.png");
  background-repeat: no-repeat;
  background-position: 72% top;
  background-size: cover;
}

.site-header {
  height: 60px;
  padding: 0 20px;
  display: flex;
  align-items: center;
  flex-shrink: 0;
  background: rgba(0, 0, 0, 0.2);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.brand__logo {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  object-fit: cover;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.brand__name {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.hero {
  flex: 1;
  display: flex;
  align-items: flex-start;
  padding: 12px 20px 32px;
}

.hero__copy {
  width: 100%;
  max-width: 420px;
  padding: 20px 16px;
  border-radius: 16px;
  background: linear-gradient(
    180deg,
    rgba(200, 238, 241, 0.95) 0%,
    rgba(200, 238, 241, 0.85) 70%,
    rgba(200, 238, 241, 0.45) 100%
  );
}

.hero__title {
  font-size: 42px;
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: 0.06em;
}

.hero__line {
  margin-top: 10px;
  font-size: 26px;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.hero__line .em-pink {
  color: var(--accent-pink);
}

.hero__line .em-teal {
  color: var(--accent-teal);
}

.hero__tagline {
  margin-top: 18px;
  font-size: 13px;
  font-weight: 500;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
  line-height: 1.5;
}

.download {
  margin-top: 28px;
}

/* 移动端：恢复原先紧凑尺寸，仅保留文字样式 */
.mobile .download-row {
  display: flex;
  flex-direction: column;
  flex-wrap: nowrap;
  align-items: flex-start;
  gap: 12px;
  width: auto;
}

.mobile .dl-card {
  border-radius: 14px;
  gap: 10px;
  box-sizing: border-box;
  justify-content: flex-start;
}

.mobile .dl-card--qr {
  width: 184px;
  height: 82px;
  padding: 0 16px 0 14px;
}

.mobile .dl-card--store {
  width: 172px;
  height: 83px;
  padding: 0 18px 0 16px;
}

.mobile .dl-card__qr {
  width: 52px;
  height: 52px;
  padding: 4px;
  border-radius: 6px;
}

.mobile .dl-card__icon {
  width: 38px;
  height: 38px;
}

.mobile .dl-card--qr .dl-card__text {
  align-items: center;
  text-align: center;
}

.mobile .dl-card--qr .dl-card__line--sm {
  font-size: 15px;
  font-weight: 600;
}

.mobile .dl-card--qr .dl-card__line--lg {
  font-size: 15px;
  font-weight: 700;
}

.mobile .dl-card--store .dl-card__text {
  align-items: flex-start;
  text-align: left;
}

.mobile .dl-card--store .dl-card__line--lg {
  font-size: 15px;
  font-weight: 700;
}

.mobile .dl-card--store .dl-card__line--sm {
  font-size: 13px;
  font-weight: 600;
}

.features {
  flex-shrink: 0;
  background: var(--bar);
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  padding: 28px 20px 32px;
  padding-bottom: 50px; /* 为底部备案留出空间 */
}

.feature {
  display: flex;
  align-items: center;
  gap: 14px;
}

.feature__icon {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  color: var(--accent-teal);
}

.feature__title {
  font-size: 16px;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.04em;
}

.feature__desc {
  margin-top: 4px;
  font-size: 12px;
  font-weight: 500;
  color: var(--bar-sub);
}

/* 底部备案 */
.foot {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 12px 20px;
  background: var(--bar);
  text-align: center;
  font-size: 12px;
  line-height: 1.4;
  color: #fff;
  z-index: 100;
}

.foot a {
  color: #fff;
  text-decoration: none;
  transition: color 0.15s ease;
}

.foot a:hover {
  color: rgba(255, 255, 255, 0.8);
}



.features {
  padding-bottom: 32px;
}

@media (min-width: 560px) and (max-width: 960px) {
  .features {
    grid-template-columns: 1fr 1fr;
    row-gap: 22px;
  }

  .hero__title {
    font-size: 52px;
  }

  .hero__line {
    font-size: 32px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .dl-card {
    transition: none;
  }
}