style.css

@import url('https://fonts.googleapis.com/css2?family=Rubik+Moonrocks&display=swap');
*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
body{
    min-height: 100vh;
    color: white;
    font-size: 1rem;
    font-family: 'Rubik Moonrocks', cursive;
    text-transform: uppercase;
    text-shadow: 0 0 4px rgba(0, 0, 0, 0.72), 0 0 14px rgba(0, 0, 0, 0.45);
}
.panels{
    width: 100vw;
    height: 100vh;
    display: flex;
}
.panels .panel{
    background-color: rgba(0, 0, 0, 0.8);
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    cursor: pointer;
    transition:
        font-size 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
        flex 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
        background 0.2s;
}
.panel.open{
    flex: 5;
    font-size: 2rem;
}
.panel1 { background-image:url(https://source.unsplash.com/gYl-UtwNg_I/1500x1500); }
.panel2 { background-image:url(https://source.unsplash.com/rFKUFzjPYiQ/1500x1500); }
.panel3 { background-image:url(https://images.unsplash.com/photo-1465188162913-8fb5709d6d57?ixlib=rb-0.3.5&q=80&fm=jpg&crop=faces&cs=tinysrgb&w=1500&h=1500&fit=crop&s=967e8a713a4e395260793fc8c802901d); }
.panel4 { background-image:url(https://source.unsplash.com/ITjiVXcwVng/1500x1500); }
.panel5 { background-image:url(https://source.unsplash.com/3MNzGlQM7qs/1500x1500); }
.panel>*{
    flex: 1 0 auto;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transition: all .7s;
}
.panel>*:first-child{
    transform: translateY(-100%);
}
.panel.active>*:first-child{
    transform: translateY(0);
}
.panel>*:last-child{
    transform: translateY(100%);
}
.panel.active>*:last-child{
    transform: translateY(0);
}
@media(max-width:1100px){
    body{
        font-size: .8rem;
    }
    .panel.open{
        font-size: 1.5rem;
    }
}