body {
  /* overflow-y: hidden; */
  background-color: #eee;
  width: 1280px;
  height: 720px;
}

.content-container {
  position: relative;
  width: 1280px;
  height: 720px;
  background-position: center;
  background-repeat: no-repeat;
  overflow: hidden;
  /* 중요!! 상단 UI 제외한 기준으로 확대 */
  transform-origin: 0 0;
  opacity: 0;
}
.content-container::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(255, 255, 255, 1);
  z-index: -1;
}
.content-container.loaded {
  opacity: 1;
}