body{margin:0;font-family:Arial;background:#f4f7fb}.topbar{display:flex;justify-content:space-between;align-items:center;background:#009688;color:#fff;padding:14px;position:sticky;top:0}#sidebar{display:none;position:fixed;left:0;top:56px;background:#fff;width:220px;height:100%;box-shadow:2px 0 8px #999}#sidebar.open{display:block}#sidebar a{display:block;padding:12px;text-decoration:none;color:#333}.container{padding:16px;max-width:900px;margin:auto}.tabs{display:flex;gap:8px}.tab{flex:1;padding:12px;border:none;border-radius:24px;background:#ddd}.tab.active{background:#009688;color:#fff}.panel{display:none;background:#fff;border-radius:16px;padding:20px;margin-top:16px;box-shadow:0 3px 10px rgba(0,0,0,.1)}.panel.active{display:block}.btn{display:block;text-align:center;padding:14px;margin:10px 0;color:#fff;text-decoration:none;border-radius:10px}.blue{background:#2196f3}.orange{background:#fb8c00}.green{background:#43a047}