body {
	text-align: center;
	width: 750px;
	margin-right: auto;
	margin-left: auto;
	line-height: 1.7em;
}
div.cover {
   display: table;
   border-spacing: 1em 3px;
   margin: 0px;
   padding: 0px;
   width: 100%;
}

div.cover div.box1 {
   display: table-cell;
   width: 40%;
}
div.cover div.box2 {
   display: table-cell;
   width: 35%
}
div.cover div.box3 {
   display: table-cell;
}

.nav{
	margin:19px 0;
	text-align:center;
	clear:both
}
.nav a {
	margin: 20px 5px 20px 5px;
	padding: 10px;
	background-color: #8080c0;
	color: #fff;
	border-radius: 7px;
	-webkit-border-radius: 7px; /* Safari,Google Chrome用 */
	-moz-border-radius: 7px; /* Firefox用 */
	text-decoration: none;
}
@media screen and (max-width: 640px) {
   div.cover {
      display: block;
   }
   div.cover div.box1 {
      display: block;
      width: 100%;
   }
   div.cover div.box2 {
      display: block;
      width: 100%;
   }
   div.cover div.box3 {
      display: block;
      width: 100%;
   }
}

h1 {
	font-size: xx-large;
	width: auto;
}