*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}code{font-family:source-code-pro,Menlo,Monaco,Consolas,Courier New,monospace}header{background-color:#2c3e50;color:#fff;padding:20px;box-shadow:0 2px 4px #0000001a}header h1{font-size:28px;margin-bottom:15px}header nav ul{list-style:none;display:flex;gap:20px}header nav a{color:#fff;text-decoration:none;transition:opacity .3s}header nav a:hover{opacity:.8}