:root {
            --primary-color: #333;
            --secondary-color: #777;
            --background-color: #fdfdfd;
            --border-color: #eaeaea;
            --link-color: #007bff;
            --max-width: 960px;
            --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
        }

        body {
            font-family: var(--font-main);
            line-height: 1.6;
            background-color: var(--background-color);
            color: var(--primary-color);
            margin: 0;
            padding: 0;
            font-size: 16px;
        }

        .container {
            max-width: var(--max-width);
            margin: 0 auto;
            padding: 0 1.5rem;
        }

        .site-header {
            border-bottom: 2px solid var(--border-color);
            padding: 1rem 0;
            background-color: #fff;
        }

        .site-header .container {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
        }

        .site-title {
            font-size: 1.75rem;
            font-weight: 700;
            margin: 0;
            color: var(--primary-color);
            text-decoration: none;
        }

        .site-nav ul {
            margin: 0;
            padding: 0;
            list-style: none;
            display: flex;
        }

        .site-nav li {
            margin-left: 1.5rem;
        }

        .site-nav a {
            text-decoration: none;
            color: var(--secondary-color);
            font-weight: 500;
        }

        .site-nav a:hover,
        .site-nav a:focus {
            color: var(--link-color);
            text-decoration: underline;
        }

        .site-content {
            display: flex;
            flex-direction: column;
            margin-top: 2rem;
        }

        main {
            flex: 1;
        }

        article {
            padding: 1.5rem;
            background-color: #fff;
            border: 1px solid var(--border-color);
            border-radius: 8px;
        }

        .article-header {
            border-bottom: 1px solid var(--border-color);
            margin-bottom: 1.5rem;
        }

        .article-header h1 {
            font-size: 2.25rem;
            margin-top: 0;
            margin-bottom: 0.5rem;
            line-height: 1.2;
        }

        .article-meta {
            font-size: 0.9rem;
            color: var(--secondary-color);
            margin-bottom: 1.5rem;
        }
        
        .article-meta span {
            display: inline-block;
            margin-right: 1rem;
        }

        .article-meta a {
            color: var(--secondary-color);
            text-decoration: none;
        }

        .article-meta a:hover {
            color: var(--link-color);
            text-decoration: underline;
        }

        .article-content h2 {
            font-size: 1.75rem;
            margin-top: 2rem;
            margin-bottom: 1rem;
            border-bottom: 1px solid var(--border-color);
            padding-bottom: 0.25rem;
        }

        .article-content h3 {
            font-size: 1.4rem;
            margin-top: 1.5rem;
            margin-bottom: 0.75rem;
        }

        .article-content p {
            margin-bottom: 1rem;
        }

        .article-content a {
            color: var(--link-color);
        }

        .article-content blockquote {
            margin-left: 0;
            padding-left: 1.5rem;
            border-left: 4px solid var(--border-color);
            font-style: italic;
            color: var(--secondary-color);
        }

        .article-content ul,
        .article-content ol {
            margin-bottom: 1rem;
            padding-left: 2rem;
        }
        
        .article-content img,
        .article-content video {
            max-width: 100%;
            height: auto;
            border-radius: 4px;
        }

        .site-footer {
            border-top: 2px solid var(--border-color);
            margin-top: 2rem;
            padding: 2rem 0;
            text-align: center;
            font-size: 0.9rem;
            color: var(--secondary-color);
        }
        
        @media (min-width: 768px) {
            /* Sidebar styles removed */
        }

            /* Pop-Up Banner CSS */
    #popup-banner {
        position: fixed;
        left: 0;
        top: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.5); /* Semi-transparent background for overlay */
        z-index: 1000;
        display: flex;
        justify-content: center;
        align-items: center;
    }

    #popup-content {
        background-color: transparent; /* Transparent background for content */
        padding: 20px;
        border-radius: 5px;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
        text-align: center;
        position: relative;
    }

    #popup-content img {
        max-width: 100%;
        height: auto;
        display: block;
        margin: 0 auto;
    }

    #popup-close {
        position: absolute;
        top: 10px;
        right: 10px;
        font-size: 20px;
        cursor: pointer;
        color: #fff; /* White color for the close button for visibility */
    }