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

body {
    background-color: #f4f9f4;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

#game-board {
    position: relative;
    display: grid;
    grid-template-columns: repeat(4, 20vmin);
    grid-template-rows: repeat(4, 20vmin);
    gap: 2vmin;
    border-radius: 1vmin;
}

@media (max-width: 500px) {
    #game-board {
        grid-template-columns: repeat(4, 18vmin);
        grid-template-rows: repeat(4, 18vmin);
        gap: 1.5vmin;
    }

    .tile {
        width: 18vmin;
        height: 18vmin;
        font-size: 6.5vmin;
        top: calc(var(--y)*(18vmin + 1.5vmin));
        left: calc(var(--x)*(18vmin + 1.5vmin));
    }
}

.cell {
    background-color: #444;
    border-radius: 1vmin;
}

.tile {
    --y: 0;
    --x: 0;
    position: absolute;
    top: calc(var(--y)*(20vmin + 2vmin));
    left: calc(var(--x)*(20vmin + 2vmin));
    display: flex;
    justify-content: center;
    align-items: center;
    width: 20vmin;
    height: 20vmin;
    border-radius: 1vmin;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 7.5vmin;
    font-weight: bold;
    background-color: #88a7d0;
    color: black;
    transition: 100ms;
    animation: show 200ms;
}

@keyframes show {
    0% {
        opacity: 0.5;
        transform: scale(0);
    }
}

.popup-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(0, 0, 0, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.popup-window {
    background-color: #f4f9f4;
    padding: 30px 40px;
    border-radius: 12px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.3);
    max-width: 400px;
    width: 90%;
    text-align: center;
    font-family: 'Arial', sans-serif;
}

.popup-message {
    font-size: 1.2rem;
    margin-bottom: 25px;
    color: #222;
}

.popup-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px; 
    margin-top: 20px;
}

.popup-button {
    flex: 1 1 120px;
    padding: 12px 25px;
    border: none;
    border-radius: 7px;
    background-color: #88a7d0;
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
    max-width: 200px;

    display: block;     
    gap: unset;      
}

.popup-button:hover {
    background-color: #88a7d0;
    transform: scale(1.05);
}

@media (max-width: 500px) {
    .popup-window {
        padding: 20px 25px;
    }

    .popup-message {
        font-size: 1rem;
    }

    .popup-button {
        flex: 1 1 100%;
        font-size: 0.95rem;
        padding: 10px 20px;
    }
}
@media (max-width: 500px) {
    #game-board {
    grid-template-columns: repeat(4, 16vmin);
    grid-template-rows: repeat(4, 16vmin);
    gap: 1vmin;
    }

    .tile {
    width: 16vmin;
    height: 16vmin;
    font-size: 6vmin;
    top: calc(var(--y) * (16vmin + 1vmin));
    left: calc(var(--x) * (16vmin + 1vmin));
    }
}