* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: inherit;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: black;
    font-family: "Roboto", system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

main {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2rem;
}

.grid {
    display: grid;
    grid-template-columns: repeat(3, 150px);
    grid-template-rows: repeat(3, 150px);
}

.controls {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.controls input {
    background-color: transparent;
    color: white;
    padding: 0.2rem 0.5rem;
    border-radius: 0.5rem;
}

.controls p {
    color: white;
    font-size: 1.5rem;
}

.grid button {
    background-color: transparent;
    font-size: 3rem;
}

.x {
    color: #fff;
    text-shadow:
        0 0 4px #fff,
        0 0 11px #fff,
        0 0 19px #fff,
        0 0 40px #f09,
        0 0 80px #f09,
        0 0 90px #f09,
        0 0 100px #f09,
        0 0 150px #f09;
}

.o {
    color: #fff;
    text-shadow:
        0 0 7px #fff,
        0 0 10px #fff,
        0 0 21px #fff,
        0 0 42px #0fa,
        0 0 82px #0fa,
        0 0 92px #0fa,
        0 0 102px #0fa,
        0 0 151px #0fa;
}

.o-border {
    box-shadow:
        0 0 7px #fff,
        0 0 10px #fff,
        0 0 10px #fff,
        0 0 10px #0fa,
        0 0 20px #0fa,
        0 0 23px #0fa,
        0 0 25px #0fa,
        0 0 35px #0fa;
}

.x-border {
    box-shadow:
        0 0 7px #fff,
        0 0 10px #fff,
        0 0 10px #fff,
        0 0 10px #f09,
        0 0 20px #f09,
        0 0 23px #f09,
        0 0 25px #f09,
        0 0 35px #f09;
}

.start {
    background-color: transparent;
    padding: 0.5rem;
    text-transform: uppercase;
}

.start:is(:not(:disabled)) {
    color: white;
}