horiz-split-box.css

.horiz-split-box {
  width: 545px;
  height: 345px;
  background: #fff;
  position: relative;
  border: 1px solid #eee;
  border-radius: 4px;
}
.horiz-split-box .content {
  width: 545px;
}
.horiz-split-box .cover {
  top: 0;
  left: 0;
  width: 35%;
  height: 100%;
  background: #fff;
  position: absolute;
  overflow: hidden;
  z-index: 2;
}
.horiz-split-box .cover {
  background: #fbfbfb;
}
.horiz-split-box .toggle-handle {
  top: 0;
  right: 65%;
  width: 4px;
  height: 100%;
  z-index: 3;
  position: absolute;
  background: #fff;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1), 0 0 4px rgba(0, 0, 0, 0.06);
  cursor: -webkit-grab;
  cursor: grab;
}
.horiz-split-box .toggle-handle-button {
  top: 50%;
  left: -18px;
  width: 40px;
  height: 40px;
  display: block;
  margin-top: -20px;
  position: absolute;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 3px 14px rgba(0, 0, 0, 0.1), 0 0 4px rgba(0, 0, 0, 0.06);
}