.b1 {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 105vh;
    margin: 0;
    background-image: url('../img/ChatGPT-Image-r_01.jpg');
    background-size: cover;
    background-position: center;
    }
    
    .b2 {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 105vh;
    margin: 0;
    background-image: url('../img/ChatGPT-Image-r_02.jpg');
    background-size: cover;
    background-position: center;
    }
    
    .b3 {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 105vh;
    margin: 0;
    background-image: url('../img/ChatGPT-Image-r_03.jpg');
    background-size: cover;
    background-position: center;
    }