style.css

* {
    box-sizing: border-box;
}

:root {
    --grid-cols: 1;
    --grid-rows: 1;
}

body {
    margin: 0;
    padding: 0;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #29ad81;
}
section {
    height: 70%;
    width: 10%;
    display: flex;
    flex-direction: column;
    justify-content: space-evenly;  
}

button {
    font-size: large;
    color: rgba(255, 255, 255, 0.973);
    margin-top: 17%;
    margin-right: 10%;
    padding: 15%;
    margin-bottom: 17%;
    background-color: #c09e2d;
    border-style: none;
    border-radius: 5px;
    transition: 200ms;
}

button:hover {
    background-color: #a88f3c;
}

button:active {
    background-color: #f3c018;
}

.container {
    background-color: rgba(255, 255, 246);
    height: 70%;
    width: 40%;
    display: grid;
    grid-template-rows: repeat(var(--grid-rows), 1fr);
    grid-template-columns: repeat(var(--grid-cols), 1fr);
  }

.divs {
    border: rgba(92, 91, 91, 0.137) 1px solid;
}

@media (max-width:900px) {
    .container {
        height: 400px;
        width: 400px;
    }

    section {
        height: 400px;
        width: 90px;
    }

    button {
        font-size: small;
        margin: 5px;
        padding: 10px;
    }
}

@media (max-width:400px) {
    body {
        height: 95vh;
        display: grid;
        grid-template-rows: 200px 1fr;
        grid-template-areas: 'buttons'
                                'container';
        align-items: center;
        justify-content: center;
    }

    .container {
        height: 300px;
        width: 300px;
    }
  
    section {
        grid-area: buttons;
        width: 300px;
        height: 200px;
        display: grid;
        grid-template-rows: repeat(auto-fill , 1fr);
        align-items: center;
        justify-content: center;
    }
  
    button {
        width: 200px;
        font-size: small;
        padding: 10px;
        margin-top: 10px;
        margin-right: 0;
        padding: 10px;
        margin-bottom: 0;
    }
}