style.css

body{
    margin: 0;
    padding: 0;
    background-color: black;
    color: white;
    height: 90vh;
    width: 100vw;
}
header{
    color: white;
    text-align: center;
    text-shadow: 3px 3px 10px #2cff00;
    font-size: 4vh;
}
footer {
    margin: 3vh;
    text-align: center;
    font-size: 1.5vmax;
}
li {
    display: inline;
    margin: 10px 5px;
    padding: 20px;
    margin: auto;
}
.choice{
    display: block;
    width: 10vw;
    height: 7vh;
    margin: auto;
    text-align: center;
    font-size: 2vh;
    background: darkred;
    color: beige;
    text-shadow: 2px 1px 5px gold;
}
.board{
    margin: auto;
}
    
table, td{
    height: 16vh;
    width: 24vw;
    border: 10px solid white;
    border-collapse: collapse;
    text-align: center;
    font-size: 3rem;
    color: greenyellow;
}
@media screen and (max-width:800px) {
    
    table, td{
        height: 10vh;
        width: 40vw;
        border: 0.2em solid white;
        border-collapse: collapse;
        text-align: center;
        font-size: 3rem;
    }
}
@media screen and (min-width:800px) and (max-width:1100px) {
    
    table, td{
        height: 15vh;
        width: 50vw;
        border: 0.2em solid white;
        border-collapse: collapse;
        text-align: center;
        font-size: 3rem;
    }
}
    .choice:hover{
        color: wheat;
        background: darkblue;
        text-shadow: 2px 1px 5px orange;
    }
table{
    border: none;
}
#box1,#box2,#box3{
    border-top: none;
}
#box1,#box4,#box7{
    border-left: none;
}
#box3,#box6,#box9{
    border-right: none;
}
#box7,#box8,#box9{
    border-bottom: none;
}