* {margin:0; padding:0; outline:none; position:relative;
    -moz-user-select: none;
    -khtml-user-select: none;
    user-select: none;
    touch-action: none;
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -webkit-tap-highlight-color: rgba(0,0,0,0);
    -webkit-text-size-adjust: none;
}
html, body {background:#fff; font-size:0;}
body {padding:5px;}

.track {max-width:280px; margin:10px; height:15px; background-color:#f00;}
.track.h {background:url(hue.png) center center no-repeat; background-size:cover;}
.track.l:before {content:''; position:absolute; top:0; left:0; right:0; bottom:0; background:url(lightness.png) center center no-repeat; background-size:cover;}

.cur {
    cursor:pointer;
    position:absolute;
    left:0%; bottom:0px!important;
    box-sizing: border-box;
    border: 2px solid #333;
    width: 21px;
    height: 21px;
    background: none;
    border-radius: 50%;
    margin: 0 0 -3px -10px;
    box-shadow: 0px 0px 0px 2px #fff, inset 0px 0px 0px 2px #fff;
}

/*.cur:after {
    display:inline-block;
    box-sizing:border-box;
    content:'';

    width: 12px;
    height: 6px;
    border-left: 6px solid transparent;
    cursor: pointer;
    border-right: 6px solid transparent;
    border-bottom: 6px solid #333;
    position: absolute;
    left:50%;
    bottom:0px;
    margin:0 0 0 -6px;
}*/