/* ============================================================
 * 鸟人助手 — 首页(大背景 + 顶部 LOGO/栏目 + 黄色下载方框)
 * ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Bricolage+Grotesque:wght@500;700;800&family=Noto+Sans+SC:wght@400;500;700;900&display=swap');

:root {
  --yellow: #ffd020;      /* 与 btn.png 主色一致 */
  --yellow-deep: #f5b800; /* hover 加深 */
  --ink: #1a1200;         /* 黄按钮上的深色文字 */
  --font-body: 'Noto Sans SC', system-ui, sans-serif;

  /* 横向光带(中转页 page::before 柔光思路,改成首页黄调) */
  --stripe-bot: rgba(124, 91, 240, 0.42); /* 底部光带用 */
  --bg-blur: 2px;                         /* 背景图高斯模糊 */
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  font-family: var(--font-body);
  background: #060814;
  color: #fff;
  -webkit-font-smoothing: antialiased;
}

/* 整页容器 */
.home {
  position: relative;
  width: 100%;
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
  scroll-snap-align: start;
  scroll-snap-stop: always;
}

/* 大背景 BGA:开场缓慢推镜(放大 → 收到正常),只演一次 */
.home__bg {
  position: absolute;
  inset: -4px;                           /* 外扩 4px 补偿 blur 裁切 */
  background: #060814 url('../img/BGA.png') center center / cover no-repeat;
  filter: blur(var(--bg-blur));
  transform: scale(1.16);                /* 动画起始态 */
  animation: hero-zoom-out 3.2s cubic-bezier(0.16, 0.7, 0.2, 1) 0.1s both;
  /* 一次性动画:不挂常驻 will-change,浏览器在动画运行期间会自行提升合成层 */
}

@keyframes hero-zoom-out {
  from { transform: scale(1.16); }
  to   { transform: scale(1.04); } /* 留余量,避免 resize 露底 */
}

/* 遮罩:黑色不均匀地加 —— 两侧卡牌墙压暗退后、中央阅读区轻压、顶/底承托 */
.home__scrim {
  position: absolute;
  inset: 0;
  background:
    /* 顶部:承托 LOGO/栏目 */
    linear-gradient(to bottom,
      rgba(4, 6, 16, 0.62) 0%,
      rgba(4, 6, 16, 0.18) 14%,
      rgba(4, 6, 16, 0) 26%),
    /* 底部:承托按钮与箭头 */
    linear-gradient(to top,
      rgba(4, 6, 16, 0.92) 0%,
      rgba(4, 6, 16, 0.6) 20%,
      rgba(4, 6, 16, 0.26) 34%,
      rgba(4, 6, 16, 0) 48%),
    /* 左侧卡牌墙:边缘重、向内快速衰减 */
    linear-gradient(to right,
      rgba(4, 6, 16, 0.66) 0%,
      rgba(4, 6, 16, 0.34) 17%,
      rgba(4, 6, 16, 0.08) 30%,
      rgba(4, 6, 16, 0) 40%),
    /* 右侧卡牌墙 */
    linear-gradient(to left,
      rgba(4, 6, 16, 0.66) 0%,
      rgba(4, 6, 16, 0.34) 17%,
      rgba(4, 6, 16, 0.08) 30%,
      rgba(4, 6, 16, 0) 40%),
    /* 中央文字区:椭圆轻压,把余光收住但不死黑 */
    radial-gradient(ellipse 68% 54% at 50% 50%,
      rgba(4, 6, 16, 0.42) 0%,
      rgba(4, 6, 16, 0.2) 52%,
      rgba(4, 6, 16, 0) 80%);
}

/* ============================================================
 * 网格扫描线 + 底部光带(独立 .fx-overlay 覆盖层,4 屏各一个)
 * 性能要点:
 *  - 底部光带放 ::before,纯静态不重绘
 *  - 网格放 ::after,用 transform: translate3d 平移一个 18px 平铺单元
 *    (只走合成器,不触发 paint);平铺单元外扩,平移不露边
 *  - 网格仅在当前屏(.is-active)播放,离开即暂停,后台 0 开销
 * ============================================================ */
.fx-overlay {
  position: absolute;
  inset: 0;
  z-index: 1;            /* 与遮罩同层;inner 写在 DOM 末位胜出 → 不挡按钮/文字 */
  pointer-events: none;
  overflow: hidden;
}

/* 底部紫色光带 —— 两层:
 * .fx-band     外层门控:默认透明,切到该屏(.is-active)1s 淡入,切走 1s 淡出、不跟随
 * .fx-band__glow 内层呼吸:亮度 45%↔100% 缓慢起伏(呼吸灯),仅当前屏播放
 * 两层 opacity 相乘;呼吸只动 opacity,走合成器不重绘 */
.fx-band {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 1s ease;
}

.fx-band__glow {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top,
    var(--stripe-bot) 0%,
    var(--stripe-bot) 28%,
    transparent 100%) 0 100% / 100% 14% no-repeat;
}

.is-active > .fx-overlay .fx-band {
  opacity: 1;
}

.is-active > .fx-overlay .fx-band__glow {
  animation: band-breathe 4.2s ease-in-out infinite;
}

@keyframes band-breathe {
  0%, 100% { opacity: 0.45; }
  50%      { opacity: 1; }
}

/* 横 + 竖扫描线网格:外扩 18px,平移后由 overlay 的 overflow 裁掉 */
.fx-overlay::after {
  content: '';
  position: absolute;
  top: -18px;
  left: -18px;
  right: -18px;
  bottom: -18px;
  background:
    repeating-linear-gradient(to bottom,
      rgba(255, 255, 255, 0.04) 0px,
      rgba(255, 255, 255, 0.04) 1px,
      transparent 1px,
      transparent 18px),
    repeating-linear-gradient(to right,
      rgba(255, 255, 255, 0.04) 0px,
      rgba(255, 255, 255, 0.04) 1px,
      transparent 1px,
      transparent 18px);
  -webkit-mask-image: linear-gradient(to right,
    transparent 0%,
    #000 18%,
    #000 82%,
    transparent 100%);
  mask-image: linear-gradient(to right,
    transparent 0%,
    #000 18%,
    #000 82%,
    transparent 100%);
}

/* 仅当前屏播放动画并提升合成层,离开即释放,后台 0 合成开销 */
.is-active > .fx-overlay::after {
  will-change: transform;
  animation: stripe-drift 8s linear infinite;
}

@keyframes stripe-drift {
  from { transform: translate3d(0, 0, 0); }
  to   { transform: translate3d(18px, 18px, 0); }
}

@media (prefers-reduced-motion: reduce) {
  .is-active > .fx-overlay::after { animation: none; }
}

/* ============================================================
 * 右侧轮播圆点指示器
 * ============================================================ */
.side-dots {
  position: fixed;
  top: 50%;
  right: 34px;
  z-index: 60;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  transform: translateY(-50%);
}

.side-dot {
  position: relative;
  width: 10px;
  height: 10px;
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.4);
  cursor: pointer;
  transition: width 0.3s ease, height 0.3s ease, border-radius 0.3s ease,
    background-color 0.3s ease, box-shadow 0.3s ease;
}

.side-dot:hover { background: rgba(255, 255, 255, 0.75); }

.side-dot.is-active {
  width: 10px;
  height: 26px;
  border-radius: 6px;
  background: var(--yellow);
  box-shadow: 0 0 12px rgba(255, 208, 32, 0.75);
}

/* ============================================================
 * 整屏吸附滚动容器
 * ============================================================ */
.snap-wrap {
  height: 100vh;
  height: 100dvh;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
  /* 整屏吸附 + 只有 4 屏,不需要滚动条;保留滑动切屏体验 */
  scrollbar-width: none;          /* Firefox */
  -ms-overflow-style: none;       /* IE / 旧 Edge */
}
.snap-wrap::-webkit-scrollbar {
  display: none;                  /* Chrome / Edge / Safari */
}

/* 程序化整屏跳转动画进行中:强制关闭吸附,避免与逐帧滚动打架 */
.snap-wrap.is-animating {
  scroll-snap-type: none !important;
}

/* ============================================================
 * 全局固定顶部导航:LOGO + 栏目(每屏保留)
 * ============================================================ */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 30px 56px;
  pointer-events: none; /* 容器不挡滚动/点击,仅内部元素可交互 */
}

/* 导航自身的顶部黑→透明渐变,四屏统一承托 LOGO/栏目 */
.site-nav::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(to bottom,
    rgba(4, 6, 16, 0.92) 0%,
    rgba(4, 6, 16, 0.62) 42%,
    rgba(4, 6, 16, 0) 100%);
}

.site-nav > * { pointer-events: auto; }

.site-nav__logo {
  display: block;
  height: 44px;
  width: auto;
}

/* 栏目 */
.tabs {
  display: flex;
  align-items: center;
  gap: 4px;
}

.tab {
  position: relative;
  display: inline-flex;
  align-items: center;
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: rgba(255, 255, 255, 0.66);
  background: none;
  border: 0;
  padding: 10px 22px 14px;
  text-decoration: none;
  cursor: pointer;
  transition: color 0.2s ease;
}

.tab:hover { color: #fff; }

.tab.is-active { color: var(--yellow); font-weight: 700; }

/* 选中栏目底部的黄色方框指示器 */
.tab::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 26px;
  height: 5px;
  border-radius: 3px;
  background: var(--yellow);
  box-shadow: 0 0 12px rgba(255, 208, 32, 0.7);
  opacity: 0;
  transition: opacity 0.2s ease, width 0.2s ease;
}

.tab.is-active::after { opacity: 1; }

/* ============================================================
 * 中部主内容:主标题 / 副标题 / 三个下载按钮
 * ============================================================ */
.home__content {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 60px;
}

.panel { display: none; width: 100%; }
.panel.is-active { display: block; animation: panel-in 0.35s ease both; }

@keyframes panel-in {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* 主标题:品牌大字 + 黄色定位行 两层排版 */
.hero-title {
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  color: #fff;
}

.hero-title__brand {
  font-size: 84px;
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: 0.04em;
  text-shadow: 0 4px 30px rgba(0, 0, 0, 0.55);
}

/* 定位行:黄色宽字距,两侧短横线 */
.hero-title__tagline {
  display: inline-flex;
  align-items: center;
  gap: 18px;
  font-size: 21px;
  font-weight: 700;
  letter-spacing: 0.42em;
  text-indent: 0.42em; /* 末字视觉居中补偿字距 */
  color: var(--yellow);
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.6);
}
.hero-title__tagline::before,
.hero-title__tagline::after {
  content: '';
  width: 44px;
  height: 2px;
  border-radius: 1px;
  background: linear-gradient(90deg, transparent, var(--yellow));
}
.hero-title__tagline::after {
  background: linear-gradient(90deg, var(--yellow), transparent);
}

/* 副标题:两侧装饰线、居中一行 */
.hero-sub {
  margin: 28px 0 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  font-size: 20px;
  font-weight: 400;
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.86);
  text-shadow: 0 2px 18px rgba(0, 0, 0, 0.6);
  white-space: nowrap;
}
.hero-sub__line {
  flex: none;
  width: 56px;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.55));
}
.hero-sub__line:last-child {
  background: linear-gradient(90deg, rgba(255, 255, 255, 0.55), transparent);
}

/* 第三排:下载按钮组 */
.hero-actions {
  margin-top: 48px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 2px;
}

/* 黄色下载方框(btn.png 底图,321x76 ≈ 4.2:1) */
.dl-btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 236px;
  height: 60px;
  padding: 0 38px;
  color: #5E2D00;
  text-decoration: none;
  background: url('../img/btn.png') center / 100% 100% no-repeat;
  transition: transform 0.22s ease;
}

.dl-btn__icon {
  width: 28px;
  height: 28px;
  object-fit: contain;
  margin-right: 10px;
  flex: none;
}

.dl-btn__text {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 0;
  white-space: nowrap;
  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.35);
}

/* "包脚本" 小字:无背景,与主文字同色 */
.dl-btn__text small {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0;
  margin-left: 6px;
  color: inherit;
}

.dl-btn:hover { transform: translateY(-3px); }

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

/* ============================================================
 * 底部引导下滑箭头(ydjt.png)
 * ============================================================ */
.home__more {
  position: absolute;
  left: 50%;
  bottom: 34px;
  z-index: 3;
  display: block;
  width: 46px;
  height: 43px;
  margin: 0;
  padding: 0;
  border: 0;
  background: none;
  transform: translateX(-50%);
  cursor: pointer;
  text-decoration: none;
  animation: more-bob 1.8s ease-in-out infinite;
}

.home__more:hover { opacity: 0.85; }

.home__more img {
  display: block;
  width: 100%;
  height: 100%;
}

@keyframes more-bob {
  0%, 100% { transform: translateX(-50%) translateY(0); opacity: 0.75; }
  50%      { transform: translateX(-50%) translateY(10px); opacity: 1; }
}

/* ============================================================
 * 第二屏:产品介绍(BGB 背景)
 * ============================================================ */
.features {
  position: relative;
  width: 100%;
  height: 100vh;
  height: 100dvh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 110px 24px 80px;
  background: #060814;
  overflow: hidden;
  scroll-snap-align: start;
  scroll-snap-stop: always;
}

/* 背景外层包裹:负责入场推镜(放大→收到正常),裁剪住内层视差位移 */
.features__bg-wrap {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
}
/* 放大初始态仅在有 JS 时存在,滚入后加 .is-bg-in 收到正常;无 JS 直接正常尺寸 */
.js .features__bg-wrap {
  transform: scale(1.14);
  transition: transform 1.6s cubic-bezier(0.16, 0.7, 0.2, 1);
}
.js .features__bg-wrap.is-bg-in { transform: scale(1); }

/* BGB 背景独立层(供视差位移),放大留出位移余量 */
.features__bg {
  position: absolute;
  inset: -8% 0;
  background: #060814 url('../img/BGB.png') center center / cover no-repeat;
  filter: blur(var(--bg-blur));
  /* 持续视差只动 transform;filter 恒定,不放入 will-change(避免常驻大块模糊缓冲) */
  will-change: transform;
  backface-visibility: hidden;
}

/* 遮罩:与首页同一思路 —— 两侧卡牌墙压暗、中央阅读区轻压、顶/底承托 */
.features::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: 1;
  background:
    /* 顶部:承托 LOGO/栏目 */
    linear-gradient(to bottom,
      rgba(4, 6, 16, 0.6) 0%,
      rgba(4, 6, 16, 0.18) 14%,
      rgba(4, 6, 16, 0) 26%),
    /* 底部:承托按钮与箭头 */
    linear-gradient(to top,
      rgba(4, 6, 16, 0.9) 0%,
      rgba(4, 6, 16, 0.58) 20%,
      rgba(4, 6, 16, 0.24) 34%,
      rgba(4, 6, 16, 0) 48%),
    /* 左右两侧卡牌墙 */
    linear-gradient(to right,
      rgba(4, 6, 16, 0.62) 0%,
      rgba(4, 6, 16, 0.3) 17%,
      rgba(4, 6, 16, 0.07) 30%,
      rgba(4, 6, 16, 0) 40%),
    linear-gradient(to left,
      rgba(4, 6, 16, 0.62) 0%,
      rgba(4, 6, 16, 0.3) 17%,
      rgba(4, 6, 16, 0.07) 30%,
      rgba(4, 6, 16, 0) 40%),
    /* 中央阅读区:椭圆压暗 */
    radial-gradient(ellipse 74% 60% at 50% 48%,
      rgba(4, 6, 16, 0.52) 0%,
      rgba(4, 6, 16, 0.26) 55%,
      rgba(4, 6, 16, 0) 82%);
  pointer-events: none;
}

.features__inner {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 980px;
  text-align: center;
}

.features__title {
  margin: 0;
  font-size: 58px;
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: 0.02em;
  color: #fff;
  text-shadow: 0 4px 30px rgba(0, 0, 0, 0.6);
}

.features__title .accent {
  color: var(--yellow);
}

/* 标题下的黄色宽字距定位行(与首页 hero 统一) */
.features__tagline {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin: 22px 0 0;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.32em;
  text-indent: 0.32em;
  color: var(--yellow);
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.6);
}
.features__tagline::before,
.features__tagline::after {
  content: '';
  flex: none;
  width: 42px;
  height: 2px;
  border-radius: 1px;
  background: linear-gradient(90deg, transparent, var(--yellow));
}
.features__tagline::after {
  background: linear-gradient(90deg, var(--yellow), transparent);
}

.features__desc {
  margin: 32px auto 0;
  max-width: 880px;
  font-size: 17px;
  font-weight: 400;
  line-height: 2;
  letter-spacing: 0.02em;
  color: rgba(255, 255, 255, 0.86);
  text-shadow: 0 2px 16px rgba(0, 0, 0, 0.7);
}

.features__actions {
  margin-top: 44px;
}

/* 第三屏:云手机(BGC 背景) */
.features--cloud .features__bg {
  background-image: url('../img/BGC.png');
}

.features--cloud .features__title {
  font-size: 52px;
}

/* 黄色菱形分隔的三条卖点 */
.feature-points {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0;
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
}
.feature-points li {
  position: relative;
  padding: 0 30px;
  font-size: 22px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: rgba(255, 255, 255, 0.92);
  text-shadow: 0 2px 16px rgba(0, 0, 0, 0.7);
  white-space: nowrap;
}
.feature-points li + li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  width: 8px;
  height: 8px;
  background: var(--yellow);
  transform: translateY(-50%) rotate(45deg);
}

.features--cloud .features__actions {
  margin-top: 46px;
}

/* 第四屏:iOS(BGD 为亮色背景,需更深的中央压暗承托白字) */
.features--ios .features__bg {
  background-image: url('../img/BGD.png');
}

/* 第四屏亮天空:在通用遮罩之外,最底再垫一层整体深色,并加深中央 */
.features--ios::before {
  background:
    linear-gradient(to bottom,
      rgba(4, 8, 24, 0.62) 0%,
      rgba(4, 8, 24, 0.2) 14%,
      rgba(4, 8, 24, 0) 26%),
    linear-gradient(to top,
      rgba(4, 8, 24, 0.92) 0%,
      rgba(4, 8, 24, 0.62) 20%,
      rgba(4, 8, 24, 0.3) 34%,
      rgba(4, 8, 24, 0.02) 48%),
    linear-gradient(to right,
      rgba(4, 8, 24, 0.6) 0%,
      rgba(4, 8, 24, 0.3) 17%,
      rgba(4, 8, 24, 0.08) 30%,
      rgba(4, 8, 24, 0) 40%),
    linear-gradient(to left,
      rgba(4, 8, 24, 0.6) 0%,
      rgba(4, 8, 24, 0.3) 17%,
      rgba(4, 8, 24, 0.08) 30%,
      rgba(4, 8, 24, 0) 40%),
    radial-gradient(ellipse 76% 62% at 50% 48%,
      rgba(4, 8, 24, 0.66) 0%,
      rgba(4, 8, 24, 0.42) 55%,
      rgba(4, 8, 24, 0.06) 82%),
    /* 最底一层:整体压暗亮天空 */
    rgba(4, 8, 24, 0.4);
}

/* ============================================================
 * 滚动入场动画(IntersectionObserver 加 .is-visible)
 * 仅在 JS 可用时隐藏初始态,避免无 JS 时内容不可见
 * ============================================================ */
.js .reveal {
  opacity: 0;
  transform: translateY(40px);
  transition:
    opacity 0.85s cubic-bezier(0.22, 0.61, 0.36, 1),
    transform 0.85s cubic-bezier(0.22, 0.61, 0.36, 1);
  /* 入场仅一次,不常驻 will-change;由 JS 在播完后清掉内联样式 */
}

.js .reveal--d1 { transition-delay: 0.14s; }
.js .reveal--d2 { transition-delay: 0.28s; }

.js .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* 尊重系统"减少动态效果"设置 */
@media (prefers-reduced-motion: reduce) {
  .snap-wrap { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
  .features__bg { transform: none !important; }
  .js .features__bg-wrap { transform: none; transition: none; }
  .home__bg { animation: none; transform: scale(1.04); }
  .fx-overlay::after { animation: none !important; }
  .fx-band { transition: none; }
  .fx-band__glow { animation: none; }
}

/* ============================================================
 * 响应式
 * ============================================================ */
@media (max-width: 900px) {
  .hero-title { gap: 12px; }
  .hero-title__brand { font-size: 56px; }
  .hero-title__tagline { font-size: 16px; letter-spacing: 0.34em; text-indent: 0.34em; gap: 14px; }
  .hero-title__tagline::before,
  .hero-title__tagline::after { width: 32px; }
  .hero-sub { font-size: 17px; margin-top: 22px; gap: 14px; white-space: normal; }
  .hero-sub__line { width: 40px; }
  .features__title { font-size: 40px; }
  .features--cloud .features__title { font-size: 37px; }
  .features__tagline { font-size: 16px; letter-spacing: 0.26em; text-indent: 0.26em; gap: 14px; margin-top: 18px; }
  .features__tagline::before,
  .features__tagline::after { width: 30px; }
  .feature-points { margin-top: 22px; }
  .feature-points li { font-size: 18px; padding: 0 22px; }
  .features__desc { font-size: 16px; line-height: 1.9; margin-top: 26px; }
}

@media (max-width: 720px) {
  .side-dots { right: 18px; gap: 12px; }
  .side-dot { width: 8px; height: 8px; }
  .side-dot.is-active { height: 22px; }
  .site-nav {
    flex-direction: column;
    gap: 12px;
    padding: 22px 20px 0;
  }
  .site-nav__logo { height: 36px; }
  .tab { font-size: 16px; padding: 8px 18px 12px; }
  .home__content { padding: 150px 20px 48px; }
  .hero-title { gap: 10px; }
  .hero-title__brand { font-size: 42px; letter-spacing: 0.03em; }
  .hero-title__tagline { font-size: 13px; letter-spacing: 0.26em; text-indent: 0.26em; gap: 10px; }
  .hero-title__tagline::before,
  .hero-title__tagline::after { width: 22px; }
  .hero-sub { font-size: 13px; margin-top: 16px; gap: 10px; letter-spacing: 0.04em; }
  .hero-sub__line { width: 24px; }
  .hero-actions { gap: 2px; margin-top: 34px; }
  .dl-btn { min-width: 0; height: 58px; padding: 0 22px; }
  .dl-btn__icon { width: 24px; height: 24px; margin-right: 7px; }
  .dl-btn__text { font-size: 20px; }
  .home__more { width: 38px; height: 36px; bottom: 22px; }
  .features { padding: 130px 18px 60px; }
  .features__title { font-size: 29px; line-height: 1.3; }
  .features--cloud .features__title { font-size: 27px; line-height: 1.3; }
  .features__tagline { font-size: 14px; letter-spacing: 0.2em; text-indent: 0.2em; gap: 10px; margin-top: 14px; }
  .features__tagline::before,
  .features__tagline::after { width: 22px; }
  .features__desc { font-size: 14px; line-height: 1.85; margin-top: 20px; }

  /* 卖点在手机上纵向排列,菱形改为居中分隔 */
  .feature-points {
    flex-direction: column;
    gap: 18px;
    margin-top: 20px;
  }
  .feature-points li {
    font-size: 16px;
    padding: 0;
  }
  .feature-points li + li::before {
    left: 50%;
    top: -13px;
    width: 6px;
    height: 6px;
  }
  .features__actions { margin-top: 30px; }
  .features--cloud .features__actions { margin-top: 30px; }
}

/* ============================================================
 * 第 4 屏底部抽屉:友情联系 + 联系我们
 * 固定在 .features--ios 底部,200px 高,深色遮罩,
 * 滚到屏 4 自动出现(其他屏看不见,屏 4 占满视口时占 iOS 屏底部)。
 * ============================================================ */
.contact-drawer {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 3;                          /* 在 .features__inner(z 1)之上,在 .home__more(z 3)同层 */
  height: 200px;
  padding: 24px 48px 22px;
  background: linear-gradient(to top,
    rgba(4, 6, 16, 0.96) 0%,
    rgba(4, 6, 16, 0.88) 60%,
    rgba(4, 6, 16, 0) 100%);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  pointer-events: auto;
}

.contact-drawer__inner {
  max-width: 1180px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: flex-end; /* 友情联系紧挨在"联系我们"上方,整体靠抽屉底部 */
  gap: 16px;
}

/* 友情联系 — 水平一排 6 个,纯文字链接 */
.contact-friends {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 22px;
  font-size: 13px;
  line-height: 1.1;
  color: rgba(255, 255, 255, 0.42);
}
.contact-friends__label {
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.6);
  margin-right: 6px;
}
.contact-friends li a {
  color: rgba(255, 255, 255, 0.7);
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: color 0.2s ease;
}
.contact-friends li a:hover {
  color: var(--yellow);
}

/* 分隔线 */
.contact-friends {
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  padding-bottom: 16px;
}

/* 联系我们 */
.contact-us {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 22px;
  font-size: 13px;
  line-height: 1.1;
  color: rgba(255, 255, 255, 0.72);
}
.contact-us__label {
  font-weight: 600;
  color: rgba(255, 255, 255, 0.6);
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.contact-us__item {
  color: rgba(255, 255, 255, 0.78);
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: color 0.2s ease;
}
.contact-us__item:hover { color: var(--yellow); }

/* 抽屉响应式:小屏压缩 padding,友情联系换行 */
@media (max-width: 900px) {
  .contact-drawer { padding: 20px 32px 18px; }
  .contact-friends, .contact-us { gap: 16px; font-size: 12px; }
}
@media (max-width: 720px) {
  .contact-drawer { height: 220px; padding: 18px 20px 16px; }
  .contact-friends { gap: 10px 14px; font-size: 12px; }
  .contact-us { gap: 12px; font-size: 12px; }
}