只需添加top: 30px;或margin-top: 30px;

这个变体帮助我：

margin: 0 0 50em 0;

.poptrox-popup {
    background: #1a1f2c;
    background: rgba(18, 21, 29, 0.9);      
    cursor: default;
    /*vertical-align: top;*/ /* Does not work */
    /*top: 30px;*/ /* Does not work */
    /*margin-top: 30em;*/ /* It works, but it shifts down to the bottom */
    margin: 0 0 50em 0; /* It shifts up as I need and rest against the top of the page when the page is resized vertically */
}