* {
  margin: 0;
}

div {
  background: url(nanimo_nai.png) center/cover;
  height: 100vh;
  position: fixed;
  width: 100%;
}
.box {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;

  /* 左右中央寄せ */
  -webkit-box-pack: center;
  -ms-flex-pack: center;
  justify-content: center;

  /* 上下中央寄せ */
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
  
  color:#fefefe;
  font-size:0;
  font-family: 'Noto Serif JP', sans-serif;
  }