.gallery { 
    display: flex;
    flex-flow: row wrap;     /* Required for responsive layout. */
    margin:0; 
    padding:0;
}

.gallery figure {            /* Modify all of these values to improve your design. */
    width: 320px; 
    margin:1%; 
    padding:1%; 
    border:; 
    background-color:;    
}

.gallery figcaption {
    display:block; 
    padding: 1% 1% 2% 1%;     /* Modify to improve spacing. */
}

.gallery img  {
    width:100%;
    margin:0;
    padding:0;
}

.gallery iframe {
    width:100%;
    height:200px;
}