caption_opacity_n_scale.css

body{
    padding: 1rem;
}
.gallery{
    display: grid;
    list-style-type: none;
    padding: 0;
    margin: 0;
    grid-gap: 1rem;
    grid-template-columns: repeat(auto-fit,minmax(300px,1fr));
    grid-auto-rows: 300px;
    grid-auto-flow: dense;
}
/*this is added*/
.gallery li figure{
    margin: 0;
    width: 100%;
    height: 100%;
    position: relative;
}
/* ---------------- */
.wide{
    grid-column: span 2;
}
.tall{
    grid-row: span 2;
}
img{
    width: 100%;
    height: 100%;
    display: block;
    object-fit: cover;
}

/* Add effect here */

/*image show top above*/
.gallery figure figcaption{
    position: absolute;
    top: 0;
    left: 0;
    background: #fff;
    width: calc(100% - 2rem);
    height: calc(100% - 2rem);
    margin: 1rem;
    text-align: center;
    display: grid;
    align-content: center;
    transition: filter .3s ease-in-out;
    filter: opacity(0);
}
.gallery figure p{
    font-style: italic;
}
.gallery figure figcaption:hover{
    filter: opacity(80%);
}