/* パズルのアイコン */
.sample_problems img{
 background-color:#bb9911;
 border:solid 5px #ffff99;
 float:left;
 margin:0px 5px 5px 0px;
}

/* heightを指定しないとオンマウスで高さが変わる */
.sample_problems h3{
 clear:both;
 height:1.5em;
}

.sample_problems h3 a{
 border:none;
 display: block;
 width: 100%;
}

.sample_problems h3 a:hover{
 background-color:#ffff00;
 border:none;
}

#main_contents h2{
 margin-top:100px;
}