style.css

:root {
    --first-color: #FF204E;
    --second-color: #A0153E;
    --third-color: #5D0E41;
    --fourth-color: #00224D;
}
#game-board {
    display: grid;
    grid-template-columns: repeat(3, 15vw);
    grid-template-rows: repeat(3, 20vh);
}
#game-board div {
    display: grid;
    place-items: center;
    background-color: var(--third-color);
    font-size: 10vh;
    text-align: center;
    border: 1px solid black;
    cursor: pointer;
    transition: 0.7s;
}
body {
    background-color: var(--first-color);
    display: flex;
    flex-direction: column;
    gap: 2rem;
    align-items: center;
    justify-content: center;
    color: var(--fourth-color);
    font-size: 2rem;
}
label {
    display: flex;
    gap: 20px;
    letter-spacing: 1rem;
}
#playerNames {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}
button {
    padding: 1rem;
    font-size: 1rem;
    background-color: var(--second-color);
    border: 0;
    margin: 1rem;
    border-radius: 2%;
    transition: 0.5s;
    cursor: pointer;
}
button:hover,
#game-board div:hover {
    opacity: 50%;
    color: #ffff;
    transition: 0.5s;
}
#game-board div:hover {
    transition: 0.7s;
}
input {
    border: 0;
    text-align: center;
    background-color: var(--second-color);
    font-size: 1rem;
}
input:hover {
    border: 0;
    opacity: 50%;
    background-color: #ffff;
}