html {
  height: 100%;
}

body {
  margin: 0;
  height: 100%;
  overflow-y: scroll;
  font-family: 'Hiragino Kaku Gothic ProN', Meiryo, sans-serif;
  background-color: #a0a0a0;
}

body > div {
  width: 640px;
  max-width: 100%;
  min-width: 360px;
  margin: 0px auto;
  min-height: 100%;
  height: auto !important;
  height: 100%;
  position: relative;
  background-color: #fff;
}

h1 {
  margin: 0 10px;
  font-size: 1.3em;
  height: 40px;
  line-height: 40px;
  text-align: center;
}

p {
  margin: 1.5em 1.5em;
  line-height: 2em;
}

p > span {
  display: inline-block;
}

img {
  margin: 0.5em auto;
  display: block;
  width: 100%;
  max-width: 480px;
  height: auto;
}

header {
  padding: 0;
  color: #fff;
  background-color: #303030;
}

main {
  display: block;
  padding: 20px 0 60px;
  color: #404040;
}

footer {
  text-align: center;
  position: absolute;
  bottom: 0;
  width: 100%;
  height: 40px;
  line-height: 40px;
  color: #fff;
  background-color: #303030;
  overflow-y: hidden;
}