div{
 /* ボックス表示用 */
 /* border: solid 3px red; */
 border: none;
 box-sizing: border-box;

 }
 
.adbox1{
 width: 950px;
 height:300px;
 border-color: black;
}
.box3, .box4{
  float:left;
  border-color: yellow;
 }
 
.box5 {
 clear:both;
 float:left;
}

.box6{
 margin-top: 10px;
 float:left;
 border-color: blue;
}

.box7{
 margin-top: 10px;
 float: left;
 border-color: green;
}

.box8{
 width: 950px;
 height: 500px;
 border-color: black;
}

.box9, .box10{
  float:left;
  border-color: yellow;
 }
 
.box11{
 clear:both;
 width: 950px;
 height: 200px;
 border-color: blue;
}