body {
        font-family: 'Arial', sans-serif;
        background-color: #f5f5f5; /* Light neutral background */
        color: #333; /* Dark gray for text */
        margin: 0;
        padding: 20px;
        display: flex;
        justify-content: center;
        align-items: center;
        min-height: 100vh;
        user-select: none;
    }

    .collapsible-container {
        background: #fff; /* Classic white background */
        border: 1px solid #ccc; /* Subtle gray border */
        border-radius: 8px;
        overflow: hidden;
        margin-bottom: 20px;
        width: 540px;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); /* Light shadow */
        transition: transform 0.3s ease, box-shadow 0.3s ease;
    }

    .collapsible-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 15px;
        cursor: pointer;
        background-color: #f9f9f9; /* Light gray background for header */
        font-size: 1.1em;
        color: #333;
        transition: background 0.3s ease, color 0.3s ease;
        user-select: none; /* Prevent text selection */
    }

    .collapsible-header:hover {
        background-color: #f0f0f0; /* Slightly darker gray on hover */
    }

    .collapsible-header .icon {
        font-size: 18px;
        font-weight: bold;
        transition: transform 0.3s ease, color 0.3s ease;
    }

    .collapsible-header.expanded .icon {
        transform: rotate(45deg); /* Rotate '+' to '×' */
        color: #666; /* Darker gray for expanded state */
    }

    .collapsible-content {
        display: none;
        padding: 15px;
        background: #fff; /* Match container background */
        color: #555; /* Slightly lighter gray text for instructions */
        font-size: 1em;
        line-height: 1.6;
        border-top: 1px solid #eee; /* Separator line between header and content */
    }

    .collapsible-content p,
    .collapsible-content ul {
        margin: 0;
    }

    .collapsible-content ul {
        list-style-type: disc;
        padding-left: 20px; /* Indent list items */
    }

    .collapsible-content li {
        margin-bottom: 10px;
    }

    .collapsible-content li:last-child {
        margin-bottom: 0;
    }

    textarea[readonly] {
        background-color: #f9f9f9; /* Light background for a disabled look */
        border: 1px solid #ccc;    /* Subtle border */
        cursor: text;             /* Keep the text cursor */
    }    


        /* Style for the diverter message */
        #mobileWarning {
            display: none;
            background-color: #ffcccb;
            color: #000;
            text-align: center;
            padding: 10px;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
            font-size: 16px;
            font-family: Arial, sans-serif;
        }

        /* Show the warning on screens narrower than 768px */
        @media screen and (max-width: 768px) {
            #mobileWarning {
                display: block;
            }

            /* Optionally, hide other content */
            body > *:not(#mobileWarning) {
                display: none;
            }
        }