style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html{
    font-size: 62.5%;
}
.container{
    width: 100vw;
    height: 100vh;
    background: linear-gradient(rgb(69, 175, 69), rgb(255, 255, 127));
    display: flex;
    justify-content: center;
    align-items: center;
}
.snake-board{
    width: 45vw;
    height: 90vh;
    background: rgb(237, 237, 148);
    border: 0.2rem solid rgb(0, 0, 0);
    margin: 0 auto;
    display: grid;
    grid-template-rows: repeat(20, 1fr);
    grid-template-columns: repeat(20, 1fr);
}
.snake-head{
    background-color: red;
    border-radius: 1rem;
    -webkit-border-radius: 1rem;
    -moz-border-radius: 1rem;
    -ms-border-radius: 1rem;
    -o-border-radius: 1rem;
}
.snake-body{
    background-color: purple;
    border-radius: 1rem;
    -webkit-border-radius: 1rem;
    -moz-border-radius: 1rem;
    -ms-border-radius: 1rem;
    -o-border-radius: 1rem;
}
.snake-food{
    background-color: aqua;
}
.score-div{
    position: absolute;
    top: 4rem;
    right: 10rem;
    padding: 1rem 2rem;
    border: 3px solid black;
    border-radius: 5rem;
    font-size: 2.5rem;
    font-weight: bolder;
    letter-spacing: 0.2rem;
    background: transparent;
    -webkit-border-radius: 5rem;
    -moz-border-radius: 5rem;
    -ms-border-radius: 5rem;
    -o-border-radius: 5rem;
}