.about_me_background {
  margin-left: 6%;
  margin-right: 6%;
  padding-bottom:8%;
  padding-top:8em;
  z-index: 100;
  height: 100vh;
}

#about_me_body {
  background-color: #F1F1F1;
}

#about_me_avatar {
/* img是inline元素，把它变成块元素之后就占一行了，左右设置成auto就可以了 */
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 9em;
}
#about_me_title {
  padding-top: 1em;
  text-align: center;
  font-family: Source Sans Pro;
  font-weight: 900;
  font-size: 2em;
  color: #2e2d2d;
}
#about_me_passage_div {
  padding-top: 1em;
  display: block;
  margin-left: auto;
  margin-right: auto;
  max-width: 70em;
}
#about_me_passage {
  font-family: Source Sans Pro;
  font-weight: 350;
  font-size: 1.1m;
  color: #8a8a8a;
  letter-spacing: 0.05em;
  line-height: 1.8em;
  padding-left: 0.5em;
  padding-right: 0.5em;
}
#about_me_short_info {
  color: #656565;
  text-align: center;
  font-size: 1.2em;
  font-family: Source Sans Pro;
  font-weight: 600;
}