* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: #333;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            font-size: 16px;
        }

        .container {
            display: flex;
            min-height: 100vh;
        }

        /* Navigation Sidebar */
        #navbar {
            position: fixed;
            top: 0;
            left: 0;
            width: 300px;
            height: 100vh;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            border-right: 3px solid #4a90e2;
            overflow-y: auto;
            z-index: 1000;
            transition: transform 0.3s ease;
        }

        #navbar header {
            background: linear-gradient(135deg, #4a90e2, #357abd);
            color: white;
            padding: 20px;
            text-align: center;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
        }

        #navbar h1 {
            font-size: 1.5rem;
            font-weight: 700;
        }

        #navbar ul {
            list-style: none;
            padding: 20px 0;
        }

        #navbar li {
            margin: 0;
        }

        #navbar a {
            display: block;
            text-decoration: none;
            color: #333;
            padding: 12px 20px;
            border-bottom: 1px solid #eee;
            transition: all 0.3s ease;
            font-weight: 500;
        }

        #navbar a:hover {
            background: linear-gradient(135deg, #4a90e2, #357abd);
            color: white;
            transform: translateX(5px);
        }

         /* Pure-CSS dropdown using <details> and <summary> */      

        /* Remove default marker arrow */
        details.dropdown summary::-webkit-details-marker {
            display: none;
        }

        details.dropdown summary::marker {
            display: none;
        }

        details.dropdown summary {
            padding: 12px 20px;
            font-size: 16px;
            color: #333;
            display: flex;
            justify-content: space-between;
            align-items: center;
            list-style: none;
            cursor: pointer;
            font-weight: 500;
            transition: all 0.3s ease;
        }

        details.dropdown summary:hover {
            background: linear-gradient(135deg, #4a90e2, #357abd);
            color: white;
            transform: translateX(5px);
        }

        /* Caret icon rotates when open */
        details.dropdown summary .fa-caret-down {
            transition: transform 0.3s ease;
            font-size: 0.9rem;
            color: #333333ce;

        }

        details.dropdown[open] summary .fa-caret-down {
            transform: rotate(180deg);
        }

        /* Items inside the dropdown */
        details.dropdown a {
            padding: 10px 30px;
            font-size: 1rem;
            color: #555;
            border-bottom: 1px solid #ddd;
            display: block;
            text-decoration: none;
            transition: all 0.3s ease;
            background: rgba(245, 245, 245, 0.9);
            border-left: 3px solid #4a90e2;
            border-right: 3px solid #4a90e2;
            margin-left: 1rem;
        }

        details.dropdown a:hover {
            background: linear-gradient(135deg, #e3f2fd, #bbdefb);
            color: #2c3e50;
            transform: translateX(3px);            
        }

        /* Main Content */
        #main-doc {
            margin-left: 300px;
            padding: 40px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            min-height: 100vh;
            width: calc(100% - 300px);
        }

        .main-section {
            margin-bottom: 60px;
            padding: 30px;
            background: white;
            border-radius: 15px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
        }

        .main-section header {
            margin-bottom: 25px;
            padding-bottom: 15px;
            border-bottom: 3px solid #4a90e2;
        }

        .main-section h2 {
            color: #2c3e50;
            font-size: 2.2rem;
            font-weight: 700;
            background: linear-gradient(135deg, #4a90e2, #357abd);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .main-section h3 {
            color: #34495e;
            font-size: 1.6rem;
            margin: 25px 0 15px 0;
            font-weight: 600;
        }

        .main-section h4 {
            color: #2c3e50;
            font-size: 1.3rem;
            margin: 20px 0 10px 0;
            font-weight: 600;
        }

        .main-section p {
            margin-bottom: 15px;
            font-size: 1.05rem;
            color: #444;
            text-align: justify;
        }

        .main-section ul {
            margin: 15px 0;
            padding-left: 30px;
        }

        .main-section li {
            margin-bottom: 8px;
            color: #555;
        }

        /* Code blocks */
        code {
            background: linear-gradient(135deg, #f8f9fa, #e9ecef);
            padding: 20px;
            border-radius: 8px;
            font-family: 'Courier New', monospace;
            display: block;
            margin: 20px 0;
            border-left: 4px solid #4a90e2;
            overflow-x: auto;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
        }

        /* Feature boxes */
        .feature-box {
            background: linear-gradient(135deg, #f1f3f4, #ffffff);
            padding: 20px;
            margin: 20px 0;
            border-radius: 10px;
            border-left: 5px solid #4a90e2;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
        }

        .highlight {
            background: linear-gradient(135deg, #fff3cd, #ffeaa7);
            padding: 15px;
            border-radius: 8px;
            margin: 15px 0;
            border-left: 4px solid #f39c12;
        }

        mark {
            background: linear-gradient(135deg, #ffecb3, #ffe082);
            color: #333;
            border-radius: 4px;
            padding: 1px 4px;
            font-family: "Cascadia Code", "Fira Code", monospace;
        }

        #references a {
            color: #4a90e2;
            text-decoration: none;
        }

        #references a:hover {
            text-decoration: underline;
        }

        #references li {
            list-style-type: disc;
            color: #4a90e2;
            padding-left: 20px;
            margin-top: 10px;
            font-size: 1.05rem;
        }

        hr {
            border: 2px solid #4a90e2;
            margin-top: 20px;
            margin-bottom: 15px;
        }

        .analogy {
            font-style: italic;
            color: #555;
            margin: 10px 0 20px 20px;
        }        

        .custom-checkmark {
            margin-right: 5px;
            font-size: 1.1em;
        }

        .recommendations {
            list-style: none;
        }

        .java_recommendations {
            margin-bottom: 2rem;
        }

        /* Table */

        table {
            width: 100%;
            border-collapse: collapse; /* This will make borders touch, but we'll apply them to cells */
            margin: 35px 0;             
            border: 1px solid #ccc; /* Overall table border */
        }

        th, td {
            padding: 12px 15px;
            text-align: center;
            border-bottom: 1px solid #ddd;
            border-right: 1px solid #ddd; /* Vertical line for cells */
        }

        th {
            background-color: #f2f2f2;
            font-weight: bold;
            color: #333;       
            white-space: nowrap;     
        }

        /* Remove border-right from the last column cells and headers */
        th:last-child,
        td:last-child {
            border-right: none;
        }
        
        tr:nth-child(even) {
            background-color: #f9f9f9;
        }

        tr:hover {
            background-color: #f1f1f1;
        }
        
        td mark {
            background-color: #e8e8e8;
            padding: 2px 4px;
            border-radius: 3px;
            font-family: "Cascadia Code", "Fira Code", monospace;
            white-space: nowrap; /* Prevents code examples from breaking across lines */
        }

        td:nth-child(2) {
             text-align: justify;
        }

        .align {
            text-align: justify;
        }

        /* Footer */
        footer {
            background: linear-gradient(135deg, #4a90e2, #357abd);
            color: white;
            text-align: center;
            padding: 20px;
            width: 100%;
            box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
        }

        footer p {
            margin: 0;
            font-size: 1rem;
            margin-left: 250px;
            font-size: 1.05rem;
        }

        footer a {
            color: #ffffff;
            text-decoration: none;
        }

        footer a:hover {
            text-decoration: underline;
            font-weight: bold;
        }

        /* Mobile hamburger menu */
        .menu-toggle {
            display: none;
            position: fixed;
            top: 20px;
            left: 20px;
            z-index: 1001;
            background: #4a90e2;
            color: white;
            border: none;
            padding: 10px;
            border-radius: 5px;
            cursor: pointer;
            font-size: 18px;
        }

        /* Mobile Responsive */
        @media screen and (max-width: 768px) {
            .menu-toggle {
                display: block;
            }

            #navbar {
                transform: translateX(-100%);
                width: 280px;
            }

            #navbar.active {
                transform: translateX(0);
            }

            #main-doc {
                margin-left: 0;
                width: 100%;
                padding: 80px 20px 40px 20px;
            }

            .main-section {
                padding: 20px;
                margin-bottom: 40px;
            }

            .main-section h2 {
                font-size: 1.8rem;
            }

            .main-section h3 {
                font-size: 1.4rem;
            }

            .main-section h4 {
                font-size: 1.2rem;
            }

            .main-section p {
                font-size: 1rem;
            }

            code {
                padding: 15px;
                font-size: 0.9rem;
            }
        }

        @media screen and (max-width: 480px) {
            #main-doc {
                padding: 80px 15px 30px 15px;
            }

            .main-section {
                padding: 15px;
            }

            .main-section h2 {
                font-size: 1.6rem;
            }

            .main-section h3 {
                font-size: 1.3rem;
            }
        }

        /* Smooth scrolling */
        html {
            scroll-behavior: smooth;
        }

        /* Additional styling for better visual appeal */
        .java-logo {
            text-align: center;
            margin: 20px 0;
            font-size: 4rem;
            color: #4a90e2;
        }

        .module-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 20px;
            margin: 20px 0;
        }

        .module-card {
            background: linear-gradient(135deg, #f8f9fa, #ffffff);
            padding: 20px;
            border-radius: 10px;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            border-left: 4px solid #4a90e2;
        }