html body {
    margin: 0;
    padding: 0;
    font-size: 16px;
    font-weight: bold;
    background: #2193b0;  /* fallback for old browsers */
    background: -webkit-linear-gradient(to top, #6dd5ed, #2193b0);  /* Chrome 10-25, Safari 5.1-6 */
    background: linear-gradient(to top, #6dd5ed, #2193b0); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
    color: aliceblue;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    position: relative;
    text-align: center;
}

#title {
    width: 100%;
    color: aliceblue;
    position: fixed;
}

#fly {
    position: relative;
    cursor: pointer;
}

.flyBefore {
    left: 100%;
}

.flyAfter {
    left: 0;
    transition: left 2s ease-in;
}

.onClickFly {
    left: -100%;
    transition: left 2s ease-out;
}

.contents {
    position: relative;
    top: 100px;
}

.footer {
    position: fixed;
    width: 100%;
    text-align: center;
    bottom: 0;
}