body {
    background-color: #000;
    color: #fff;
    line-height: 150%;
}

#container {
    width: 100%;
    max-width: 480px;
    margin-right: auto;
    margin-left: auto;
}
#heder-navi {
    margin-left: 40px;
}
#field {
    position: relative; 
    overflow: hidden; 
    margin-left:20px;
    margin-top:20px;
}

#start-buttons {
    position: absolute;
    width: 100%;
    left: 0px;
    top:150px;
    text-align: center;
}
#ctrl-buttons {
    position: absolute;
    width: 100%;
    left: 0px;
    top:270px;
    text-align: center;
}
#left, #right {
    background-color: transparent;
    border: white 2px solid;
    width: 100px;
    height: 50px;
    color: white;
    margin: 0px 10px 0px 10px;
    font-weight: bold;
}
#start, #go-ranking {
    font-weight: bold;
    text-align: center;
	font-size: 18px;
	width: 280px;
    border: none;
    font-size: 16px;
    background-color: #1DA1F2;
    padding: 10px 32px;
    border-radius: 100vh;
    color: white;
    cursor: pointer;
}

#go-ranking {
    margin-top: 40px;
}

.display-none {
    display: none;
}

.footer-content a {
    color: #00bfff;
}

.footer-content a:hover {
    color: #f00;
}