body {
    font-family: "ヒラギノ角ゴ ProN", "ヒラギノ角ゴ Pro", "Hiragino Kaku Gothic ProN", "Hiragino Kaku Gothic Pro", "游ゴシック", "Yu Gothic", "メイリオ", "Meiryo UI", Meiryo, Osaka, "ＭＳ Ｐゴシック", "MS PGothic", sans-serif;
    margin: auto;
    width: 900px;
}

header {
    background-color: #ffffff;
    position: fixed;
    width: 900px;
    height: 4em;
}

.header_icon {
    float: left;
    padding: .5em;
}
.icon_img {
    width: 3em;
    height: auto;
}

.header_title {
    font-family: "ヒラギノ明朝 ProN", "ヒラギノ明朝 Pro", "Hiragino Mincho ProN", "Hiragino Mincho Pro", "游明朝", "Yu Mincho", "ＭＳ Ｐ明朝", "MS PMincho", serif;
    font-size: 2rem;
    float: left;
    padding: .2em;
}

main {
    padding-top: 4em;
}

.menu {
    position: fixed;
    height: 400px;
    width: 16em;
    padding: 1em;
}

.contents {
    margin-left: 18em;
    height: 1200px;
    width: auto;
    padding: 1em;
}

.contents .heading {
    font-size: 1.5em;
    font-weight: bold;
    margin-top: -3em;
    padding-top: 3em;
}

.contents #text {
    padding-top: .5em;
    padding-bottom: 1em;
}