styles.css

@media(min-width:320px) {
    .main-container {
        display: grid;
        grid-template-columns: 100%;
        grid-template-rows: 25% auto auto auto;
        grid-template-areas: 
            "header"
            "block-1"
            "block-2"
            "block-3";
        color: black;
    }
    header {
        grid-area: header;
        background-color: #A35822;
        padding: 55px;
    }
    article {
        background-color: lightgrey;
    }
    
    .block-1 {
        grid-area: block-1;
    }
    
    .block-2 {
        grid-area: block-2;
    }
    
    .block-3 {
        grid-area: block-3;
    }
}

@media(min-width:992px) {
    .main-container {
        height: 100vh;
        display: grid;
        grid-template-columns: repeat(3, 1fr);
        grid-template-rows: repeat(2, 1fr);
        grid-template-areas: 
            "header header header"
            "block-1 block-2 block-3";
        color: white;
    }
    header {
        grid-area: header;
        background-color: #2999A3;
    }
    article {
        background-color: rgb(20, 20, 20);
    }
    
    .block-1 {
        grid-area: block-1;
    }
    
    .block-2 {
        grid-area: block-2;
    }
    
    .block-3 {
        grid-area: block-3;
    }
}

header {
    display: flex;
    justify-content: center;
    align-items: center;
}

article {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 60px;
    line-height: 20px;
}

p {
    display: inline-block;
    width: 200px;
    font-family: 'Nunito', sans-serif;
}

h1 {
    color: white;
    font-family: 'Shippori Mincho B1', serif;
    font-size: 55px;
}

h2 {
    font-family: 'Shippori Mincho B1', serif;
    font-size: 40px;
}

.color-block {
    width: 200px;
    height: 30px;
}

#color-1 {
    background-color: #A35822;
}

#color-2 {
    background-color: #B5F4FA;
}

#color-3 {
    background-color:#2999A3;
}