.ofsrbase {
    position: relative;
}
.ofsrwrap {
    width: 90%;
    margin: 1em auto;
    overflow-x: auto;
}
.mousedownb {
    text-align: center;
    font-family: arial, sans-serif;
    display: inline-block;
    height: 1.2em;
    width: 1.2em;
    line-height: 1;
    border-radius: 100%;
    background-color: #1ea0c6;
    opacity: 0.4;
    color: #fff;
    font-size: 2em;
    transform: rotate(-90deg);
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    margin: auto;
    cursor: pointer;
}
.mousedowna {
    text-align: center;
    font-family: arial, sans-serif;
    display: inline-block;
    height: 1.2em;
    width: 1.2em;
    line-height: 1;
    border-radius: 100%;
    background-color: #1ea0c6;
    opacity: 0.4;
    color: #fff;
    font-size: 2em;
    transform: rotate(90deg);
    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    margin: auto;
    cursor: pointer;
}