.scrubber {
    margin-top: 10px;
    width: 200px;
    height: 40px;
    position: relative;
}

.scrubber .track {
    position: absolute;
    top: 50%;
    left: 0px;
    width: 100%;
    height: 6px;
    background: #DDD;
    border-radius: 3px;
    margin-top: -3px;
}

.scrubber .thumb {
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    position: absolute;
    top: 50%;
    left: 0px;
    width: 22px;
    height: 22px;
    margin-left: -11px;
    margin-top: -11px;
    cursor: pointer;
    opacity: 0.7;
    border: 8px solid #BECFE4;
    border-radius: 100%;
    background: #4F81BD;
    transition: border-width 0.2s ease 0s;
}

.scrubber .thumb:hover {
  border-width: 0px;
  opacity: 1;
}

.scrubber {
    margin-top: 10px;
    width: 200px;
    height: 40px;
    position: relative;
}

.scrubber .track {
    position: absolute;
    top: 50%;
    left: 0px;
    width: 100%;
    height: 6px;
    background: #DDD;
    border-radius: 3px;
    margin-top: -3px;
}

.scrubber .thumb {
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    position: absolute;
    top: 50%;
    left: 0px;
    width: 22px;
    height: 22px;
    margin-left: -11px;
    margin-top: -11px;
    cursor: pointer;
    opacity: 0.7;
    border: 8px solid #BECFE4;
    border-radius: 100%;
    background: #4F81BD;
    transition: border-width 0.2s ease 0s;
}

.scrubber .thumb:hover {
  border-width: 0px;
  opacity: 1;
}

.thumb.dragging {
  border-width: 0px;
  opacity: 1;
}

Add .dragging class for full opacity on drag
Add .dragging class for full opacity on drag