header{background:#0073e6;color:white;padding:10px 0;text-align:center}header h1{margin:0;font-size:2em}nav{display:flex;justify-content:space-around;background:#005bb5;padding:10px 0}nav a{color:white;text-decoration:none;padding:10px 20px;font-weight:700;transition:background .3s ease}nav a:hover{background:#004494}main{padding:20px}@media (max-width:768px){nav{flex-direction:column}nav a{text-align:center;padding:15px 0;border-bottom:1px solid #004494}}@media (max-width:480px){header h1{font-size:1.5em}.container{padding:10px}}