.intro-video { position: relative; }
.video-sound-button {
  position: absolute;
  z-index: 1;
  top: 10px;
  right: 10px;
  min-height: 44px;
  padding: 8px 14px;
  border: 1px solid rgb(255 255 255 / 65%);
  border-radius: 24px;
  background: rgb(7 29 43 / 90%);
  color: #fff;
  font: 700 14px/1.5 Arial, "Microsoft YaHei", "PingFang SC", sans-serif;
  cursor: pointer;
}
.video-sound-button:hover { background: #071d2b; }
.video-sound-button:focus-visible { outline: 3px solid #a6e847; outline-offset: 3px; }
@media (max-width: 620px) {
  .video-sound-button { top: 8px; right: 8px; padding: 8px 12px; }
}