.box {
    background: red;
    width: 5vw;
    height: 10vh;
    position: absolute;
    top: 10vh;
    left: 5vw;
}

<div class="box"></div>

没有什么好办法（阅读：* 可靠 *）来做到这一点。抱歉了。
你所要求的基本上归结为检测浏览器的缩放级别，这里有一个很好的答案（确认这有多困难）：

• 如何在所有现代浏览器中检测页面缩放级别？

正如答案中所述，有一种“有点”跨浏览器疯狂的方式涉及使用Flash，但也有缺点：

• 它使用Flash。
• 如果用户 * 加载了你的页面 * 已经放大了，这是不可靠的。
• 它使用Flash。是的，这太糟糕了，我说了两次。想想那些iPhone/iPad。

不管怎样，它在这里：
http://blog.sebastian-martens.de/2009/12/how-to-detect-the-browser-zoom-level-change-browser-zoo/

要使div大小不随缩放而变化（但不随其中的内容变化），请执行以下操作：
在你的css里面，这个div：

**最小宽度：100%;

max-width：100%;**
这将冻结宽度，你也可以对高度做同样的事情。

我不知道你的意思，只是用CSS：

div#id {
    width: 100px; /*or some other #*/
    height: 100px; /*or some other #*/
}

联系我们

<div id="id">some content</div>

你应该能够在css中使用px度量来设置宽度和高度
例如

div
{
width:100px; height:200px;
}

我在另一篇文章中读到了一个我还没有测试过的解决方案...
Maintain div size (relative to screen) despite browser zoom level
这是使用的javascript：

//This floating div function will cause a div to float in the upper right corner of the screen at all times. However, it's not smooth, it will jump to the proper location once the scrolling on the iPhone is done. (On my Mac, it's pretty smooth in Safari.) 

function flaotingDiv(){

    //How much the screen has been zoomed.
    var zoomLevel = ((screen.width)/(window.innerWidth));
    //By what factor we must scale the div for it to look the same.
    var inverseZoom = ((window.innerWidth)/(screen.width));
    //The div whose size we want to remain constant.
    var h = document.getElementById("fontSizeDiv");

    //This ensures that the div stays at the top of the screen at all times. For some reason, the top value is affected by the zoom level of the Div. So we need to multiple the top value by the zoom level for it to adjust to the zoom. 
    h.style.top = (((window.pageYOffset) + 5) * zoomLevel).toString() + "px";

    //This ensures that the window stays on the right side of the screen at all times. Once again, we multiply by the zoom level so that the div's padding scales up.
    h.style.paddingLeft = ((((window.pageXOffset) + 5) * zoomLevel).toString()) + "px";

    //Finally, we shrink the div on a scale of inverseZoom.
    h.style.zoom = inverseZoom;

}

//We want the div to readjust every time there is a scroll event:
window.onscroll = flaotingDiv;