.panes-container {
    display: flex;
    width: 100%;
    overflow: hidden;
}

.left-pane {
    width: 18%;
    background: #ccc;
}

.panes-separator {
    width: 1px;
    border: 1px outset #777777;
    background: #777777;
    box-shadow: 0px 0px 10px black;
    position: relative;
    cursor: col-resize;
}

.right-pane {
    flex: auto;
    background: #eee;
}

.panes-container,
.panes-separator{
    margin: 0;
    padding: 0;
    height: 100%;
}
.left-pane,
.right-pane {
    margin: 0;
    padding: 0px;
    padding-left: 1em;
    height: 100%;
}