.desktop {
  position: relative;
  width: 100%;
  height: 100vh;
  overflow: hidden;
}

/* 背景 */
.pc-bg {
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  z-index: 0;
}

/* 左上角 APP 图标 */
.pc-icon {
  position: absolute;
  top: 3%;
  left: 3%;
  z-index: 2;
}
.pc-icon img {
  width: 6vw;
  max-width: 90px;
  border-radius: 16px;
}

/* 右上角按钮 */
.pc-top-btns {
  position: absolute;
  top: 3%;
  right: 3%;
  display: flex;
  gap: 12px;
  z-index: 2;
}
.top-btn img {
  height: 3vw;
  max-height: 44px;
  min-height: 30px;
}
.top-btn {
  text-decoration: none;
  transition: opacity 0.2s;
}
.top-btn:hover {
  opacity: 0.85;
}

/* 中央标题 logo */
.pc-logo {
  position: absolute;
  top: 18%;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  text-align: center;
}
.pc-logo img {
  width: 42vw;
  max-width: 650px;
}

/* 二维码下载区：水平居中，放在背景中间下方的空白区（大飞 10-28） */
.pc-download {
  position: absolute;
  bottom: 5%;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* 二维码框（763x283 宽图，QR 码在左侧粉色边框正中） */
.qr-wrap {
  position: relative;
  width: 40vw;
  max-width: 640px;
  min-width: 360px;
}
.qr-frame-img {
  width: 100%;
  display: block;
}
/* QR 码定位在左侧边框中央（边框图透明框实测：中心 x=18.1%, y=50.2%，宽 25.0%） */
.qr-inner {
  position: absolute;
  top: 50%;
  left: 18.2%;
  transform: translate(-50%, -50%);
}
.qr-inner img,
.qr-inner canvas {
  display: block;
}