* {
  margin: 0;
}
#event1 {
  display: flex;
  width: 100vw;
  justify-content: center;
  position: relative;
}
#event1-img {
  width: 50%;
  position: absolute;
}
#event1-link {
  position: absolute;
  width: 50%;
  height: 5vw;
  top: 196.5vw;
  left: 25vw;
 <!-- background: rgba(244, 4, 4, 0.8); -->
}
@media only screen and (max-width: 768px) {
  #event1 {
  }
  #event1-img {
    width: 100%;
  }
  #event1-link {
    position: absolute;
    width: 100%;
    height: 12vw;
    top: 392vw;
    left: 0;
    
 <!--  background: rgba(244, 4, 4, 0.8); -->
  }
}