如何在页面向下扩展的情况下保持网页底部的页脚

html, body {
    height: 100%;
}

.container {
    min-height: 100%;
    display: flex;
    flex-direction: column;
}

.content {
    flex: 1;
}

.footer {
    flex-shrink: 0;
}

function setFooterPosition() {
    var contentHeight = document.getElementById("content").offsetHeight;
    var windowHeight = window.innerHeight;
    var footer = document.getElementById("footer");

    if (contentHeight < windowHeight) {
        footer.style.position = "fixed";
        footer.style.bottom = "0";
    } else {
        footer.style.position = "relative";
        footer.style.bottom = "";
    }
}

window.addEventListener("resize", setFooterPosition);