.container {
    position: fixed;

    top: 50px;
    bottom: 50px;
    left: 0;
    right: 0;

    width: 100%;
    height: auto;

    min-width: 0;
    min-height: 0;

    margin: 0;
    padding: 0;

    overflow: auto;
    overscroll-behavior: contain;

    box-sizing: border-box;
}