css A4 format adapted to multiple browsers

I must create a dynamic page through php, and the result must be an A4 printable page. Up here no problem, I have the page, and with Google Chrome I can view and print in A4 perfectly.

but

if I change the web browser, the A4 1 page is splitted into 2 pages (the last 2 or 3 lines on the 2nd page)

How may I adapt the print following the used browser? (maybe using css, or java, or php?)

thank everybody for your help

in my css I have this:

    .page {
    width: 210mm;
    min-height: 297mm;
    padding: 2mm;
    margin: 5mm auto;
    border: 1px #ffffff solid;
    border-radius: 5px;
    background: white;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.1);
}


@page {
    size: A4;
    margin: 0;
}
@media print {
    html, body {
        width: 210mm;
        height: 297mm;        
    }
    .page {
        margin: 0;
        border: initial;
        border-radius: initial;
        width: initial;
        min-height: initial;
        box-shadow: initial;
        background: initial;
        page-break-after: always;
    }
}