* {
    box-sizing: border-box;
}
body{
    margin: 0;
}
 
.container{
    width:100%;
    min-height: 100vh;
    background-color: aqua;
 
}

main {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100vw;
    min-height: 100vh; 
    flex-flow: row wrap;
    gap: 20px; 
    padding: 20px;
}

.box {
    position: relative;
    
    width: 30%; 
    min-width: 250px; 
    height: 250px;
    overflow: hidden;
    border: 15px solid grey;
    border-radius: 15px;
}

.box img {
    width: 100%;
    height: 100%;
    object-fit: cover; 
    position: absolute;
    top: 0;
    left: 0;
    transition: opacity 0.5s ease;
}

.hover_img {
    opacity: 0;
}


.box:hover .hover_img {
    opacity: 1;
}