IPython/html/static/notebook/less/quickhelp.less

.quickhelp {
    .hbox();
}
.shortcut_key {
    display: inline-block;
    width: 20ex;
    text-align: right;
    font-family: @font-family-monospace;
}

.shortcut_descr {
    display: inline-block;
    .box-flex1();
}