/* --- Base Styles & System Fonts --- */
        :root {
            --bg-color: #f3f4f6;
            --card-bg-color: #ffffff;
            --text-color: #1f2937;
            --text-muted-color: #6b7280;
            --border-color: #d1d5db;
            --primary-color: #2563eb;
            --primary-hover-color: #1d4ed8;
            --shadow-color: rgba(0, 0, 0, 0.1);
            --header-footer-bg: #ffffff;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
            background-color: var(--bg-color);
            color: var(--text-color);
            display: flex;
            flex-direction: column;
            min-height: 100vh;
            margin: 0;
            box-sizing: border-box;
        }

        /* --- Header --- */
        .page-header {
            background-color: var(--header-footer-bg);
            padding: 1rem 2rem;
            box-shadow: 0 2px 4px var(--shadow-color);
            width: 100%;
            box-sizing: border-box;
            z-index: 10;
        }
        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            max-width: 1200px;
            margin: 0 auto;
        }
        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
        }
        .main-nav ul {
            margin: 0;
            padding: 0;
            list-style: none;
            display: flex;
            flex-wrap: wrap;
            gap: 1.5rem;
        }
        .main-nav a {
            text-decoration: none;
            color: var(--text-muted-color);
            font-weight: 500;
            transition: color 0.2s;
        }
        .main-nav a:hover {
            color: var(--primary-color);
        }
        
        /* --- Main Content Area --- */
        main {
            flex-grow: 1;
            display: flex;
            justify-content: center;
            padding: 2rem 1rem;
            width: 100%;
            box-sizing: border-box;
        }

        /* --- Content Article --- */
        .content-article {
            width: 100%;
            max-width: 42rem; /* 672px, good for reading */
            background-color: var(--card-bg-color);
            border-radius: 1rem;
            box-shadow: 0 10px 15px -3px var(--shadow-color), 0 4px 6px -4px var(--shadow-color);
            padding: 2rem 2.5rem; /* More padding for readability */
            margin: 2rem 0;
            box-sizing: border-box;
        }
        .content-article h1 {
            font-size: 2.5rem; /* Larger for article title */
            font-weight: 700;
            margin-top: 0;
            margin-bottom: 1rem;
        }
        .content-article p {
            font-size: 1.125rem; /* Slightly larger font for body */
            line-height: 1.7;
            margin-bottom: 1.5rem;
        }
        .content-article h2 {
            font-size: 1.875rem;
            font-weight: 600;
            border-bottom: 1px solid var(--border-color);
            padding-bottom: 0.5rem;
            margin-top: 2rem;
            margin-bottom: 1rem;
        }
         .content-article a {
            color: var(--primary-color);
            text-decoration: none;
            border-bottom: 1px solid var(--primary-color);
            transition: background-color 0.2s;
        }
        .content-article a:hover {
            background-color: rgba(37, 99, 235, 0.1);
        }
        .content-article img {
            max-width: 100%;
            height: auto;
            border-radius: 0.5rem; /* Optional: adds rounded corners to match the theme */
            display: block;
            margin: 1.5rem 0; /* Adds vertical space around the image */
        }
        
        /* --- Footer --- */
        .page-footer {
            background-color: var(--header-footer-bg);
            padding: 1.5rem 2rem;
            text-align: center;
            color: var(--text-muted-color);
            font-size: 0.875rem;
            border-top: 1px solid var(--border-color);
            width: 100%;
            box-sizing: border-box;
        }

        /* --- Responsive Styles --- */
        @media (max-width: 640px) {
            .header-content {
                flex-direction: column;
                gap: 1rem;
            }
            .main-nav ul {
                justify-content: center;
                gap: 1rem;
            }
            main {
                padding: 1rem;
            }
            .content-article {
                padding: 1.5rem;
                margin: 1rem 0;
            }
            .content-article h1 {
                font-size: 2rem;
            }
            .content-article h2 {
                font-size: 1.5rem;
            }
        }