body {
            margin: 0;
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        /* Header (top) */
        #header {
            height: 120px; /* adjust as needed */
            border: none;
        }

        /* Main area (below header) */
        #main {
            flex: 1;
            display: flex;
        }

        /* Left menu */
        #menu {
            width: 150px; /* adjust as needed */
            border: none;
        }

        /* Content area */
        #content {
            flex: 1;
            border: none;
        }