style.css

* {
    margin: 0px;
    padding: 0px;
    box-sizing: border-box;
    font-family: 'Times New Roman';
    font-weight: bold;
}

body {
    background-color: grey;
}

h1 {
    height: auto;
    width: auto;
    font-size: 3rem;
    text-align: center;
    text-decoration: underline;
    margin-top: 3vh;
}

hr {
    margin: 0.5rem 0rem;
}

.winner {
    height: auto;
    width: auto;
    text-align: center;
    font-size: 2rem;
}

.hidden {
    display: none;
}

.main-box {
    border: 10px solid rgb(25, 25, 25);
    border-radius: 25px;
    height: 24rem;
    width: 24rem;
    margin: auto;
    background-color: grey;
    box-shadow: inset 3px 3px 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
}

.box {
    border-width: 0.5rem;
    border-color: rgb(50, 50, 50);
    height: 6rem;
    width: 6rem;
    background-color: rgb(220, 220, 220);
    margin: 0.5rem;
    cursor: pointer;
    font-size: 3rem;
}

.box:hover {
    box-shadow: inset 3px 3px 50px;
}

.reset {
    text-align: center;
}

#reset {
    border-width: 0.5rem;
    height: auto;
    width: auto;
    background-color: rgb(220, 220, 220);
    padding: 1rem;
    font-size: 1rem;
    cursor: pointer;
}

#reset:hover {
    box-shadow: inset 3px 3px 50px;
}