index.css

/* styles.css */
body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden; /* Prevent scrolling */
}

body {
    font-family: 'Arial', sans-serif;
    background-color: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
}

#game-container {
    display: grid;
    gap: 1px; /* Space between squares */
}

.square {
    transition: background-color 0.3s;
    box-sizing: border-box; /* Include border in the width and height */
    display: flex; 
    align-items: center; 
    justify-content: center;
}

#win-message {
    margin-top: 20px;
    font-size: 24px;
    color: #28a745;
    text-align: center;
}

.modal {
    display: none; /* Hidden by default */
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    left: 0;
    top: 0;
    width: 100%; /* Full width */
    height: 100%; /* Full height */
    background-color: rgba(0, 0, 0, 0.4); /* Black w/ opacity */
}

.modal-content {
    background-color: #fefefe;
    padding: 20px;
    border: 1px solid #888;
    width: 80%; /* Could be more or less, depending on screen size */
    text-align: center;

    /* Centering the modal correctly */
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.modal-buttons {
    margin-top: 20px;
}

.modal-buttons button {
    margin: 0 10px;
    padding: 10px 20px;
}

/* https://isotropic.co/tool/hex-color-to-css-filter/ */
.green-filter {
    filter: invert(87%) sepia(25%) saturate(612%) hue-rotate(61deg) brightness(90%) contrast(85%);
}

.red-filter {
    filter: invert(64%) sepia(45%) saturate(851%) hue-rotate(310deg) brightness(103%) contrast(101%);
}

.blue-filter {
    filter: invert(70%) sepia(48%) saturate(5255%) hue-rotate(208deg) brightness(104%) contrast(101%);
}