@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;700&display=swap');
        body {
            font-family: 'Inter', sans-serif;
            background-color: #1a202c; /* Dark background */
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            height: 100vh;
            color: #e2e8f0; /* Light text */
            padding: 1rem;
            overflow: hidden; /* Prevents overflow from particles */
        }
        .board {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 1rem;
            width: 100%;
            max-width: 20rem;
            position: relative;
        }
        .cell {
            width: 100%;
            padding-top: 100%;
            background-color: #2d3748; /* Darker gray for cells */
            border-radius: 0.75rem;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 3rem;
            font-weight: bold;
            cursor: pointer;
            transition: transform 0.2s ease, background-color 0.2s ease;
            position: relative;
        }
        .cell:hover {
            transform: scale(1.05);
            background-color: #4a5568;
        }
        .cell:active {
            transform: scale(0.95);
        }
        .cell-content {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
        }
        .x-mark {
            color: #90cdf4; /* Light blue for 'X' */
        }
        .o-mark {
            color: #f6ad55; /* Orange for 'O' */
        }
        
        /* Styling for the winning line */
        #winning-line {
            position: absolute;
            background-color: #4ADE80; /* A vibrant green */
            box-shadow: 0 0 10px #4ADE80; /* Adds a glowing effect */
            height: 0.75rem; /* Thicker line */
            opacity: 0;
            transition: opacity 0.5s ease-in-out, transform 0.5s ease-in-out, width 0.5s ease-in-out;
            transform-origin: left center;
        }

        /* Animation for the glow effect */
        @keyframes pulse-glow {
            0% {
                box-shadow: 0 0 10px #4ADE80;
            }
            50% {
                box-shadow: 0 0 20px #4ADE80;
            }
            100% {
                box-shadow: 0 0 10px #4ADE80;
            }
        }

        /* Styling and animation for the sparkles */
        .sparkle {
            position: fixed;
            top: 0;
            background-color: transparent;
            border-radius: 50%;
            pointer-events: none;
            opacity: 0;
            animation: sparkle-fall 2s ease-in forwards;
        }

        @keyframes sparkle-fall {
            0% {
                transform: translateY(0) scale(1);
                opacity: 1;
            }
            100% {
                transform: translateY(100vh) scale(0.5);
                opacity: 0;
            }
        }

        /* Fixed Header Styles */
        .fixed-header {
            position: fixed;
            top: 0;
            left: 0;
            width: 10%;
            margin-top: 1rem;
            z-index: 100; /* Ensure it's above other content but below popups */
            box-shadow: 0 0px 0px rgba(0, 0, 0, 0.1);
        }