how to make a width infinite and hidden using css

#scroller-wrapper {
    width: 100%;
    height: 200px;
    background-color: red;
}

#scroller {
    height: 100%;
    overflow-x: auto;
    white-space: nowrap;
}

.elem {
    height: 100%;
    display: inline-block;
    outline: 1px solid blue;
}