Javascript 如何居中<；img>；哪个有z索引？

我无法将图像居中，此时，它会停留在左侧。这个概念是当我点击图像时，图像的大版本会弹出给我们

HTML:

Javascript:

将

#大尺寸面板

100%宽度和中心对齐内容

.photoposition{
    width: 250px;
    height: 250px;
    margin-left: 53px;
    float: left;
    position: relative;
}

.scaledownlandscape{
    width: 250px;
    object-fit: scale-down;
    display: block;
    margin: 0 auto;
}

.divspan{
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: 1;
}

#largeImgPanel {
    visibility: hidden;
    position: fixed;
    z-index: 100;
    top: 0; 
    left: 0;
    width: 500px; 
    height: 400px;
    background-color: rgba(100,100,100, 0.5);
    margin-top: 141px;
}

---

能否请您将问题复制成一把小提琴左右..尝试将

right:0

添加到

#largeImgPanel

right:0

无效您能否将代码显示在小提琴上..如何添加小提琴@拉尔

.photoposition{
    width: 250px;
    height: 250px;
    margin-left: 53px;
    float: left;
    position: relative;
}

.scaledownlandscape{
    width: 250px;
    object-fit: scale-down;
    display: block;
    margin: 0 auto;
}

.divspan{
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: 1;
}

#largeImgPanel {
    visibility: hidden;
    position: fixed;
    z-index: 100;
    top: 0; 
    left: 0;
    width: 500px; 
    height: 400px;
    background-color: rgba(100,100,100, 0.5);
    margin-top: 141px;
}

function showImage(imgName) {
    document.getElementById('largeImg').src = imgName;
    showLargeImagePanel();
    unselectAll();
}

function showLargeImagePanel() {    
    document.getElementById('largeImgPanel').style.visibility = 'visible';
}

function unselectAll() {
    if(document.selection) document.selection.empty();
    if(window.getSelection) window.getSelection().removeAllRanges();
}

function hideMe(obj) {
    obj.style.visibility = 'hidden';
}

#largeImgPanel {
    visibility: hidden;
    position: fixed;
    z-index: 100;
    top: 0; 
    left: 0;
    right: 0;
    width: 500px; 
    height: 400px;
    background-color: rgba(100,100,100, 0.5);
    margin-top: 141px;
    text-align: center;
}