style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@500&display=swap');

* {
    box-sizing: border-box;
}

body {
    height: 100vh;
    font-family: 'Roboto', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
     margin:0;
     overflow: hidden;
}

.container {
    display: flex;
    width: 90vw;
}

.panel {
    background-repeat: no-repeat;
    background-size:cover;
    background-attachment: fixed;
    background-position: center;
    position: relative;
    height:80vh;
    border-radius: 35px;
    cursor: pointer;
    color:rgb(35, 154, 2);
    margin: 15px;
 flex:0.5;
 transition: flex 0.7s ease;

}

.panel h3 {
    font-size: 30px;
    position: absolute;
    bottom:30px;
    left: 30px;
    margin: 0;
    opacity:0;
}

.panel.active {
    flex: 5;
}

.panel.active h3 {
    opacity:1;
    transition: opacity 0.5s ease-in-out 0.3s;
}

@media (max-width: 660px) {
    .container {
        width: 100vw;
    }
    .panel:nth-of-type(5),
    .panel:nth-of-type(6) {
      display:none;
    }
}