/* Global dark theme */
body {
    background-color: #121212;
    color: white;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

h1 {
    color: cyan;
    margin-bottom: 10px;
    font-size: 2.2em;
}

#startBtn {
    background-color: #222;
    color: yellow;
    border: 2px solid yellow;
    padding: 10px 20px;
    margin-bottom: 20px;
    font-weight: bold;
    cursor: pointer;
    font-family: inherit;
}

#startBtn:hover {
    background-color: #333;
}

/* Main layout: Rules (left) + Board (right) */
.main-layout {
    display: flex;
    gap: 30px;
    align-items: flex-start;
}

/* Rules Panel */
#rules {
    background-color: #1e1e1e;
    color: white;
    padding: 20px;
    border: 2px solid yellow;
    border-radius: 8px;
    width: 280px;
    font-size: 15px;
}

#rules h2 {
    color: cyan;
    margin-top: 0;
    font-size: 1.4em;
}

#rules ul {
    padding-left: 20px;
    margin: 12px 0;
}

#rules li {
    margin-bottom: 8px;
}

#rules p {
    font-style: italic;
    color: #ccc;
    margin-top: 15px;
}

/* Game Board */
#gameBoard {
    display: grid;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: repeat(4, 100px);
    gap: 6px;
    border: 4px solid yellow;
    padding: 6px;
    background-color: #1e1e1e;
}

.cell {
    background-color: #2a2a2a;
    border: 2px solid yellow;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 28px;
    font-weight: bold;
    color: cyan;
    font-family: 'Courier New', monospace;
    user-select: none;
}