div {
}

.header {
  width: 100%;
  height: 50px;
  background-color: rgb(255,245,0);
  position: fixed;
  top: 0;
  left: 0;
  z-index:9999;
}

#content {
  background-color: rgba(0,0,255,0);
  width: 100%;
  position: absolute;
  top: 0px;
  left: 0px;
  height: 100%;
}