doctype html
css:
  #sample1 {
    position: absolute; width:200px ; height:100px ;
    background-color: yellow ;
    animation: smpl 5s linear 0s infinite alternate;
  }
  @keyframes smpl {
    0% {left:0%}
    100% {left:80%}
  }
h2 あいうえお
h4 かきくけこ
ul
  li abc
  li def
  li ghi
  li.xx jkl
  li mno

#sample1