How to center a absolute div inside a fixed div

Question

I have set up a modal for phots, so when i click on a small photo i get a larger photo up in a modal, the modal has position: fixed; and the modal-content has position: absolute; i can center it with margin: auto; left: 0; right: 0;but then the width goes all the way to the right and left, i want the modal content width to be the same as the photo inside it or the content of the modal-content

my code:

.modal {
    display: none; /* Hidden by default */
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    padding: 30px;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    width: 100%; /* Full width */
    height: 100%; /* Full height */
    overflow: auto; /* Enable scroll if needed */
    background-color: rgb(0,0,0); /* Fallback color */
    background-color: rgba(0,0,0,0.4); /* Black w/ opacity */

}

.modal-content {
    background-color: #fefefe;
    position: absolute;
    top: 50px;
    margin-bottom: 30px;
    margin: auto;
    border: 1px solid #888;
}

.modalimg {
    position: relative;
    text-align: center;
}

.modalimg  img{
    max-width: 100%;
    max-height: 400px;
    margin: auto;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0; 
    position: relative;
    box-shadow: 0 0 20px rgba(0,0,0,0.4); 

}

its maybe a bit messy now but i have tried alot of different things with no luck..

Answer 1

This is what I use when I center an absolute-positioned element, this works for me all the time:

.absolute-center {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}