body {font-family: Arial, sans-serif; margin:0;}
.sidebar {width: 220px; background:#333; color:#fff; position:fixed; top:0; bottom:0; padding:15px;}
.sidebar a {color:#fff; text-decoration:none; display:block; padding:5px;}
.topbar {background:#555; color:#fff; padding:10px; display:flex; justify-content:space-between;}
.hamburger {cursor:pointer; font-size:20px; margin-right:10px;}
.content {margin-left:230px; padding:20px;}
.login-box {width:300px; margin:100px auto; background:#eee; padding:20px; border-radius:5px;}
.error {color:red;}